<PAGE>   1




                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

           (X) QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                  For The Quarterly Period Ended June 30, 1999

                                       OR

           ( ) TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                       FOR THE TRANSITION PERIOD FROM    TO

                           COMMISSION FILE NO. 0-15098

                            JONES PHARMA INCORPORATED
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


             DELAWARE                                       43-1229854
  (STATE OR OTHER JURISDICTION OF                        (I.R.S. EMPLOYER
   INCORPORATION OR ORGANIZATION)                        IDENTIFICATION NO.)


  1945 CRAIG ROAD, ST. LOUIS, MISSOURI                         63146
 (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                    (ZIP CODE)



     REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (314) 576-6100


INDICATE BY CHECK MARK WHETHER THE REGISTRANT (1) HAS FILED ALL REPORTS REQUIRED
TO BE FILED BY SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 DURING
THE PRECEDING 12 MONTHS (OR FOR SUCH SHORTER PERIOD THAT THE REGISTRANT WAS
REQUIRED TO FILE SUCH REPORTS), AND (2) HAS BEEN SUBJECT TO SUCH FILING
REQUIREMENTS FOR THE PAST 90 DAYS. YES [X]  NO [ ].

NUMBER OF SHARES OUTSTANDING OF REGISTRANT'S COMMON STOCK AS OF JULY 26, 1999:
28,878,357





                                  PAGE 1 OF 20

<PAGE>   2

                            JONES PHARMA INCORPORATED

                                      INDEX

<TABLE>
<CAPTION>

Part I - Financial Information                                                               PAGE
                                                                                            NUMBER
                                                                                            ------
<S>                                                                                       <C>
     Item 1.  Financial Statements


         Condensed Consolidated Balance Sheets -
         December 31, 1998 and June 30, 1999                                                    3


         Condensed Consolidated Statements of Income -
         three months and six months ended June 30, 1998 and 1999                               4


         Condensed Consolidated Statements of Stockholders'
         Equity - six months ended June 30, 1998 and 1999                                       5


         Condensed Consolidated Statements of Cash Flows -
         six months ended June 30, 1998 and 1999                                                6


         Notes to Condensed Consolidated Financial Statements                              7 - 10


     Item 2.  Management's Discussion and Analysis
                      of Results of Operations and Financial Condition                      11-17



Part II - Other Information


     Item 4.  Submission of Matters to a Vote of Security Holders                              18


     Item 5.  Other Information                                                                18


     Item 6.  Exhibits and Report on Form 8-K                                                  19



Signatures                                                                                     20
</TABLE>

                                       2

<PAGE>   3

                            JONES PHARMA INCORPORATED
                      CONDENSED CONSOLIDATED BALANCE SHEETS

          (In thousands of dollars except share and per share amounts)
<TABLE>
<CAPTION>

                                                                                              December 31,       June 30,
                                                                                                 1998              1999
                                                                                                 ----              ----
<S>                                                                                             <C>             <C>
       ASSETS                                                                                                   (Unaudited)
Current assets:
       Cash and cash equivalents..........................................................     $   122,745      $   148,321
       Accounts receivable, less allowance for doubtful accounts of
       $ 977 at December 31, 1998 and $ 1,170 at June 30, 1999............................          19,069           14,865
       Inventories........................................................................           7,492           10,561
       Deferred income taxes..............................................................           3,342            3,342
       Other..............................................................................           1,329            2,073
                                                                                               -----------      -----------
Total current assets......................................................................         153,977          179,162
Net property, plant and equipment.........................................................          23,692           23,643
Net intangible assets.....................................................................          66,326           64,603
Other assets..............................................................................           4,783            4,812
                                                                                               -----------      -----------
Total assets..............................................................................       $ 248,778      $   272,220
                                                                                               ===========      ===========

       LIABILITIES AND STOCKHOLDERS' EQUITY Current liabilities:
       Accounts payable and accrued expenses..............................................     $     9,951      $    10,671
       Income taxes payable...............................................................           1,771            4,604
                                                                                               -----------      -----------
Total current liabilities.................................................................          11,722           15,275
Deferred income taxes.....................................................................           4,386            4,386
Stockholders' equity:
       Preferred stock, $.01 par value; 5,000,000 shares authorized; no shares
       issued or outstanding .............................................................               -                -

       Common stock, $.04 par value; 75,000,000 authorized, 43,198,467 issued and
       outstanding at December 31, 1998 and 43,246,303 at June 30, 1999 (See Note 2)......           1,727            1,730

       Contributed capital................................................................         110,464          110,860
       Retained earnings..................................................................         120,479          139,969
                                                                                               -----------      -----------
Total stockholders' equity................................................................         232,670          252,559
                                                                                               -----------      -----------
Total liabilities and stockholders' equity................................................     $   248,778      $   272,220
                                                                                               ===========      ===========
</TABLE>





                             See accompanying notes.

                                       3


<PAGE>   4


                            JONES PHARMA INCORPORATED
                   CONDENSED CONSOLIDATED STATEMENTS OF INCOME
                                   (UNAUDITED)
               (In thousands of dollars except per share amounts)

<TABLE>
<CAPTION>
                                                      Three Months Ended     Six Months Ended
                                                            June 30,              June 30,
                                                      -------------------    -------------------
                                                        1998         1999      1998       1999
                                                        ----         ----      ----       ----
<S>                                                   <C>         <C>        <C>        <C>
Sales from continuing operations ..................  $ 26,675     $ 31,286   $ 50,418   $ 60,762
Cost of sales .....................................     6,371        5,157     12,043     11,740
                                                     --------     --------   --------   --------
Gross profit ......................................    20,304       26,129     38,375     49,022
Selling, general and administrative expenses:
    Selling .......................................     4,239        4,725      8,339      9,499
    General and administrative ....................     2,634        2,727      4,668      5,255
    Research and development ......................        --          434       --          673
    Amortization ..................................       945          868      1,922      1,736
    Nonrecurring charge ...........................    10,500         --       10,500       --
                                                     --------     --------   --------   --------
       Total selling, general and administrative
         expenses                                      18,318        8,754     25,429     17,163
                                                     --------     --------   --------   --------

Operating income from continuing operations .......     1,986       17,375     12,946     31,859
Other income (expense):
   Interest income ................................     1,433        1,677      2,218      3,072
   Other ..........................................  (      2)    (     57)   (    31)   (    39)
                                                     --------     --------   --------   --------
Income before taxes from continuing operations ....     3,417       18,995     15,133     34,892
Provision for income taxes ........................     5,412        7,408      9,864     13,529
                                                     --------     --------   --------   --------
Income (loss) from continuing operations ..........    (1,995)      11,587      5,269     21,363
Income from discontinued operations (net of taxes):
   Gain on sale of discontinued operations ........    17,079         --       17,079       --
   Income from discontinued operations ............       468         --        1,689       --
                                                     --------     --------   --------   --------
       Income from discontinued operations ........    17,547         --       18,768       --
                                                     --------     --------   --------   --------
Net income ........................................  $ 15,552     $ 11,587   $ 24,037   $ 21,363
                                                     ========     ========   ========   ========
Earnings (loss) per share (See Note 2):
     Basic:  Continuing operations ................  $  ( .05)    $    .27   $    .12   $    .49
             Discontinued operations ..............       .41         --          .43        --
                                                     --------     --------   --------   --------
                                                     $    .36     $    .27   $    .55   $    .49
                                                     ========     ========   ========   ========
    Diluted:  Continuing operations ...............  $  ( .05)    $    .26   $    .12   $    .48
              Discontinued operations .............       .40          --         .42        --
                                                     --------    --------   --------   --------
                                                     $    .35     $    .26   $    .54   $    .48
                                                     ========    ========   ========   ========
</TABLE>



                             See accompanying notes.


                                       4
<PAGE>   5

                            JONES PHARMA INCORPORATED
            CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
                                   (UNAUDITED)
                     Six Months Ended June 30, 1998 and 1999

          (In thousands of dollars except share and per share amounts)
<TABLE>
<CAPTION>

                                     Number of shares        Preferred     Common      Contributed       Retained
                                    Preferred   Common         Stock        Stock         Capital        Earnings         Total
                                    ---------   ------         -----        -----         -------        --------         -----
<S>                                     <C>    <C>            <C>        <C>            <C>            <C>              <C>
Balance at December 31, 1997 ........    -     28,647,300     $  --      $     1,146    $   109,129     $    81,451     $   191,726
Three-for-two stock split
declared July 13, 1999 ..............    -     14,323,651        --              573           (573)           --              --
Exercise of stock options ...........    -        107,190        --                3            226            --               229
Shares tendered in payment of
option price ........................    -         (4,316)       --             --             --              --              --
Net income ..........................    -           --          --             --             --            24,037          24,037
Cash dividend declared - common
stock ($.075 per share) .............    -           --          --             --             --            (1,582)         (1,582)
                                         -    -----------     -------    -----------    -----------     -----------     -----------
Balance at June 30, 1998 ............    -     43,073,825     $  --      $     1,722    $   108,782     $   103,906     $   214,410
                                         =    ===========     =======    ===========    ===========     ===========     ===========


Balance at December 31, 1998 ........    -     43,198,467     $  --      $     1,727    $   110,464     $   120,479     $   232,670
Exercise of stock options ...........    -         48,262        --                3            362            --               365
Shares tendered in payment
of option exercise price ............    -           (426)       --             --             --              --              --
Amortization of unearned
compensation ........................    -           --          --             --               34            --                34
Net income ..........................    -           --          --             --             --            21,363          21,363
Cash dividend declared - common
stock ($.0975 per share) ............    -           --          --             --             --            (1,873)         (1,873)
                                              -----------     -------    -----------    -----------     -----------     -----------
Balance at June 30, 1999 ............    -     43,246,303     $  --      $     1,730    $   110,860     $   139,969     $   252,559
                                              ===========     =======    ===========    ===========     ===========     ===========
</TABLE>












                             See accompanying notes.


                                       5


<PAGE>   6

                            JONES PHARMA INCORPORATED
                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (UNAUDITED)
                            (In thousands of dollars)

<TABLE>
<CAPTION>
                                                                                 Six months ended
                                                                                      June 30,
                                                                             -----------------------
                                                                                1998            1999
                                                                                ----            ----
<S>                                                                            <C>             <C>
Cash flows from operating activities:
     Net income ......................................................         24,037          21,363
     Non-cash adjustments:
         Depreciation and amortization ...............................          2,864           2,800
         Provision for uncollectibles ................................            140             193
         Nonrecurring charge .........................................         10,500             --
         Pretax gain on sale of discontinued operations ..............        (30,616)            --
         Deferred income tax .........................................        ( 3,163)            --
         Loss on asset sales .........................................           --                79
     Change in assets and liabilities:
         Accounts receivable .........................................          3,409           4,011
         Inventories .................................................            802         ( 3,069)
         Other current assets ........................................        ( 1,121)        (   744)
         Accounts payable and accrued expenses .......................          6,401             720
         Income taxes payable ........................................        (   653)          2,833
                                                                              -------         -------
              Net cash from operating activities .....................         12,600          28,186
                                                                              -------         -------
Cash flows from (used for) investing activities:
     Additions to property, plant and equipment ......................        ( 1,552)        ( 1,102)
     Proceeds from sale of discontinued operations ...................         55,000             --
     Investing activities - discontinued operations ..................           --               --
                                                                              -------         -------
              Net cash from (used for) investing activities ..........         53,448         ( 1,102)
Cash flows from (used for) financing activities:
     Payment of dividends ............................................        ( 1,580)        ( 1,873)
     Proceeds from exercise of stock options .........................            229             365
                                                                              -------         -------
         Net cash from (used for) financing activities ...............        ( 1,351)        ( 1,508)
                                                                              -------         -------
Increase (decrease) in cash and cash equivalents .....................         64,697          25,576
Cash and cash equivalents, beginning of period .......................         49,877         122,745
                                                                              -------         -------
Cash and cash equivalents, end of period .............................      $ 114,574       $ 148,321
                                                                            =========       =========
</TABLE>




                             See accompanying notes.


                                       6

<PAGE>   7

                            JONES PHARMA INCORPORATED
              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                             June 30, 1998 and 1999

            (Dollars in thousands except share and per share amounts)


1.   GENERAL

     The unaudited interim financial information reflects all adjustments
     (consisting of normal recurring accruals) which management considers
     necessary for a fair presentation of the results of operations for such
     periods and is subject to year-end adjustments. Certain footnote
     disclosures normally included in financial statements prepared in
     accordance with generally accepted accounting principles have been
     condensed or omitted from the unaudited interim financial information as
     permitted by rules and regulations of the Securities and Exchange
     Commission. Management believes that the disclosures made are adequate to
     make the information presented not misleading. The results for the interim
     periods are not necessarily indicative of results for the full year. It is
     suggested that these financial statements be read in conjunction with the
     Company's audited financial statements and notes thereto for the year ended
     December 31, 1998, included in the 1998 Annual Report.

2.   COMMON STOCK SPLIT

     On July 13, 1999, the Board of Directors declared a three-for-two stock
     split effected in the form of a stock dividend to be paid on August 6, 1999
     to holders of record on July 26, 1999. The unaudited condensed consolidated
     financial statements, including stock option, share, and per share data
     have been retroactively adjusted to reflect the split.























                                       7
<PAGE>   8

3.   EARNINGS PER SHARE

     The following table sets forth the computations of basic and diluted
     earnings per share for the three months and six months ended June 30:

<TABLE>
<CAPTION>

                                                          Three Months Ended                Six Months Ended
                                                               June 30,                          June 30,
                                                  -------------------------------     ------------------------------
                                                        1998              1999             1998             1999
                                                  --------------      -----------     -------------      -----------
                                                             (Unaudited)                        (Unaudited)
<S>                                               <C>                 <C>             <C>                <C>
Numerator for basic and diluted earnings per share:
     Income (loss) from continuing operations     $       (1,995)     $    11,587     $        5,269     $    21,363
     Income from discontinued operations                  17,547             --               18,768            --
                                                  --------------      -----------     --------------     -----------

                                                  $       15,552      $    11,587     $       24,037     $    21,363
                                                  ==============      ===========     ==============     ===========
Denominator for basic earnings per
     share-weighted average shares                    43,068,000       43,230,000         43,045,500      43,222,000
Effect of dilutive stock options                         801,000        1,067,000            876,000       1,030,000
                                                  --------------      -----------     --------------     -----------

Denominator for diluted earnings per share            43,869,000       44,297,000         43,921,500      44,252,000
                                                  ==============      ===========     ==============     ===========

Earnings(loss) per share:
     Basic:  Continuing operations                 $        (.05)     $       .27     $          .12     $       .49
             Discontinued operations                         .41            --                   .43            --
                                                  --------------      -----------     --------------     -----------
                                                             .36      $       .27     $          .55     $       .49
                                                  ==============      ===========     ==============     ===========

     Diluted: Continuing operations                $        (.05)     $       .26     $          .12     $       .48
              Discontinued operations                        .40         --                      .43         --
                                                  --------------      -----------     --------------     -----------
                                                   $         .35      $       .26     $          .55     $       .48
                                                  ==============      ===========     ==============     ===========
</TABLE>

4.   INVENTORIES

     Inventories are valued at the lower of cost on a first-in, first-out basis
     or market. Inventories used in continuing operations are comprised as
     follows:

<TABLE>
<CAPTION>

                  December 31,   June 30,
                     1998         1999
                        (Unaudited)
<S>                 <C>         <C>
Raw material        $ 2,239     $ 2,615
Work-in-process         506         998
Finished goods        4,747       6,948
                    -------     -------
                    $ 7,492     $10,561
                    =======     =======
</TABLE>













                                       8
<PAGE>   9






5.   PROPERTY, PLANT AND EQUIPMENT

     Property, plant and equipment used in continuing operations are as follows:

<TABLE>
<CAPTION>

                                                  December 31,   June 30,
                                                      1998         1999
                                                                (Unaudited)
                                                  ---------     -----------
<S>                                                <C>           <C>
Land .........................................     $  2,068      $  2,068
Building and improvements ....................       11,608        11,697
Equipment and furniture ......................       16,526        16,771
Automobiles ..................................          590           655
Projects in process ..........................          128           399
                                                   --------      --------
                                                     30,920        31,590
Less accumulated depreciation and amortization       (7,228)       (7,947)
                                                   --------      --------
                                                   $ 23,692      $ 23,643
                                                   ========      ========
</TABLE>

6.   INTANGIBLE ASSETS

     Intangible assets used in continuing operations are as follows:

<TABLE>
<CAPTION>

                                                 December 31,   June 30,
                                                    1998         1999
                                                              (Unaudited)
                                                 ---------    -----------
<S>                                               <C>           <C>
Distribution systems, trademarks and licenses     $ 66,805      $ 66,697
Restrictive covenants and other intangibles.         7,647         7,647
Goodwill ....................................        4,034         4,034
                                                  --------      --------
                                                    78,486        78,378
Less accumulated amortization ...............      (12,160)      (13,775)
                                                  --------      --------
                                                  $ 66,326      $ 64,603
                                                  ========      ========
</TABLE>

7.   INCOME TAXES
     The provisions for income taxes for the three month and six month periods
     ended June 30, 1999 are based on estimated effective annual income tax
     rates of 39.0% and 38.8%, respectively. For the three month and six month
     periods ended June 30, 1998, the provisions for income taxes reflect the
     nondeductibility of the $10,500 nonrecurring charge. Excluding the effects
     of the nonrecurring charge, the estimated effective income tax rate in 1998
     approximates 38.5%.















                                       9
<PAGE>   10

8.   CONTINGENCIES

     The FDA announced in an August 14, 1997, Federal Register Notice that
     orally administered drug products containing levothyroxine sodium are now
     classified as new drugs. Manufacturers, who wish to continue to market
     these products, must submit a new drug application (NDA). After August 14,
     2000, any levothyroxine sodium product marketed without an approved NDA
     will be subject to regulatory action. Levoxyl, with total sales of
     approximately $15,000 for the six months ended June 30, 1998 and $16,000
     for the six months ended June 30, 1999, was marketed prior to the date of
     the FDA notice and therefore will continue to be eligible for marketing
     until August 14, 2000. The Company plans to dedicate significant resources
     to this NDA process during 1999 and 2000 and expects to incur costs in
     excess of $2,000 to secure an approved NDA for Levoxyl.

     The Company currently carries product liability coverage of $20,000 per
     occurrence and $20,000 in the aggregate on a "claims made" basis. In
     addition to this policy, the Company carries a $10,000 umbrella policy.
     There is no assurance that the Company's present insurance will cover any
     potential claims that may be asserted in the future. In addition, the
     Company is subject to legal proceedings and claims, which arise in the
     ordinary course of business.

     The Company is a defendant in a number of lawsuits involving the
     manufacture and sale of dexfenfluramine, fenfluramine, and phentermine
     (collectively, "Fen/Phen"). The Company distributed Obenix, its branded
     phentermine product; however, the Company did not and does not manufacture
     Obenix or other Fen/Phen combinations. It is too early to determine what,
     if any, liability the Company may have with respect to the claims set forth
     in these lawsuits. Management of the Company believes that the outcome of
     these lawsuits will not have a material adverse effect on the Company's
     business, financial condition, and results of operations.























                                       10
<PAGE>   11



           ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF RESULTS OF
                       OPERATIONS AND FINANCIAL CONDITION

     Statements contained in this discussion which are not historical facts or
     information are "forward-looking statements" as that term is used in the
     Private Securities Litigation Reform Act of 1995. Words such as "believe,"
     "expect," "intend," "will," "should" and other expressions that indicate
     future events and trends identify such forward-looking statements. These
     forward-looking statements involve risks and uncertainties which could
     cause the outcome to be materially different than stated. Such risks and
     uncertainties include both general economic risks and are discussed more
     fully in the Company's Annual Report on Form 10-K filed with the Securities
     and Exchange Commission. The Company cautions that any forward-looking
     statement reflects only the belief of the Company or its management at the
     time the statement was made. Although the Company believes such
     forward-looking statements are based upon reasonable assumptions, such
     assumptions may ultimately prove to be inaccurate or incomplete. The
     Company undertakes no obligation to update any forward-looking statement to
     reflect events or circumstances after the date on which the statement was
     made.

                  ********************************************

     The following table sets forth, for the interim periods indicated, the
     percentages which certain components of the Consolidated Statements of
     Income bear to product net sales and the percentage change of such
     components (based on aggregate dollars) as compared to the prior year.

<TABLE>
<CAPTION>

                                                                                INCREASE                          INCREASE
                                                                               (DECREASE)                        (DECREASE)
                                                                                AGGREGATE                         AGGREGATE
                                                             THREE MONTHS ENDED   DOLLAR      SIX MONTHS ENDED     DOLLAR
                                                                  June 30,        AMOUNT           June 30,        AMOUNT
                                                             ------------------   ------      -----------------    ------
                                                               1998       1999                 1998       1999
                                                               ----       ----                 ----       ----
<S>                                                           <C>        <C>        <C>       <C>        <C>        <C>
Sales from continuing operations .......................      100.0%     100.0%     17.3%     100.0%     100.0%     20.5%
Cost of sales ..........................................       23.9       16.5     (19.1)      23.9       19.3      (2.5)
                                                              -----      -----     -----      -----      -----      ----
Gross profit ...........................................       76.1       83.5      28.7       76.1       80.7      27.7
Selling, general and
     administrative expenses:
     Selling ...........................................       15.9       15.1      11.5       16.5       15.7      13.9
     General and administrative ........................        9.9        8.7       3.5        9.3        8.6      12.6
     Research and development ..........................         --        1.4       N/A        --         1.1       N/A
     Amortization ......................................        3.5        2.8      (8.1)       3.8        2.8      (9.7)
     Nonrecurring Charge ...............................       39.4        --        N/A       20.8        --        N/A
                                                              -----      -----     -----      -----      -----      ----
         Total selling, general and
            administrative expenses ....................       68.7       28.0      12.0*      50.4       28.2      14.9*
                                                              -----      -----     -----      -----      -----      ----
Operating income from
   continuing operations ...............................        7.4       55.5      39.2*      25.7       52.5      35.9*
Interest income ........................................        5.4        5.4      17.0        4.4        5.0      38.5
Other income (expense) .................................        0.0       (0.2)     N/A        (0.1)      (0.1)      N/A
                                                              -----      -----     -----      -----      -----      ----
Income before taxes from
        continuing operations ..........................       12.8       60.7      36.5*      30.0       57.4      36.1*
Provision for income taxes .............................       20.3       23.7      36.9*      19.5       22.3      37.1*
                                                              -----      -----     -----      -----      -----      ----
Income (loss) from continuing operations ...............       (7.5)      37.0      36.2*      10.5       35.1      35.5*
Income from discontinued
         operations (net of tax) .......................       65.8        --        N/A       37.2        --        N/A
                                                              -----      -----     -----      -----      -----      ----
Net income .............................................       58.3%      37.0%      N/A       47.7%      35.1%      N/A
                                                              =====      =====      ====      =====      =====      ====
</TABLE>

     *Excludes effect of $10,500 nonrecurring charge in 1998





                                       11
<PAGE>   12

SALES FROM CONTINUING OPERATIONS
QUARTER ENDED JUNE 30:

Sales from continuing operations for the three months ended June 30, 1999
increased 17.3% to $31.3 million from $26.7 million for the three months ended
June 30, 1998.

Critical Care product sales in the second quarter of 1999 were up approximately
77.0% from $6.7 million for the three months ended June 30, 1998 to $11.9
million for the three months ended June 30, 1999. Substantially all of this
increase was attributable to Thrombin-JMI with sales of $7.4 million in the
second quarter of 1999 compared to $2.3 million in 1998, despite a 17% unit
volume decline. The majority of the Company's hospital buying group contracts
were renegotiated during the first quarter of 1999 resulting in a significant
reduction in Thrombin-JMI sales discounts in the second quarter of 1999. The
Company believes the increase in the Thrombin-JMI net selling price per unit
will continue to result in an increase in total net sales, however, there can be
no assurance that the renegotiated contract pricing will not negatively impact
sales volume or result in quarterly volatility in net sales in 1999.

Endocrine product sales in the second quarter of 1999 were down 2.0% from $17.5
million for the three months ended June 30, 1998 to $17.1 million for the three
months ended June 30, 1999. Sales of Levoxyl, the Company's leading Endocrine
product, were up 3.1% from $8.8 million in the second quarter of 1998 to $9.0
million in the second quarter of 1999 with a 2.5% increase in unit volume.
Industry market share data indicates that total Levoxyl prescriptions dispensed
have increased 25% during the three months ended June 30, 1999 as compared to
the same period of 1998. The Company's reported growth in net sales of Levoxyl
may differ from industry market share data based upon the buying patterns and
inventory levels maintained by the wholesale distributors and the level of sales
discounts offered by the Company. Tapazole sales were down 18.1% from $6.9
million for the three months ended June 30, 1998 to $5.7 million for the three
months ended June 30, 1999 while Cytomel sales were up 65.3% from $2.1 million
in the second quarter of 1998 to $3.4 million in the second quarter of 1999.

Veterinary product sales were down 9.5% from $2.4 million in the second quarter
of 1998 to $2.2 million in the second quarter of 1999.

SIX MONTHS ENDED JUNE 30:

Sales from continuing operations for the six months ended June 30, 1999
increased 20.5% from $50.4 million in the second quarter of 1998 to $60.8
million in the second quarter of 1999.

Critical Care product sales for the six months ended June 30, 1999 increased
52.8% from $16.0 million in 1998 to $24.5 million for the same period of 1999.
The majority of this increase was due to Thrombin-JMI with sales of $14.6
million for the six months ended June 30, 1999 compared to $7.0 million for the
same period of 1998. The increase in Thrombin-JMI results from the renegotiated
contract pricing, described above, and a 4% unit volume increase.

Endocrine product sales increased 5.6% from $29.7 million for the six months
ended June 30, 1998 to $31.3 million for the six months ended June 30, 1999.
Levoxyl sales increased from $15.2 million for the six months ended June 30,
1998 to $16.3 million for the six months ended June 30, 1999 with a 10% increase
in unit volume. Sales of Cytomel increased from $3.1 million for the six months
ended June 30, 1998 to $5.1 million for the same period of 1999.

Year-to-date sales of veterinary products increased 4.9% from $4.7 million in
1998 to $4.9 million in 1999.



                                       12

<PAGE>   13

GROSS PROFIT

Gross profit during the three months ended June 30, 1999 increased 28.7% or $5.8
million to $26.1 million from $20.3 million in the same period of 1998. As a
percentage of sales from continuing operations, margins increased from 76.1% in
the second quarter of 1998 to 83.5% in the second quarter of 1999. The increase
is primarily due to the reduction in sales discounts associated with the
renegotiation of Thrombin-JMI pricing, discussed above.

Gross profit for the six months ended June 30, 1999 increased 27.7% or $10.6
million to $49.0 million from $38.4 million. As a percentage of sales from
continuing operations, margins increased from 76.1% in 1998 to 80.7% in 1999.
The year-over-year improvement in gross margin primarily resulted from the
Thrombin-JMI sales discount reduction, discussed above.


SELLING, GENERAL AND ADMINISTRATIVE EXPENSES

Selling expenses increased 11.5% or $.5 million to $4.7 million in the second
quarter of 1999 due to a net increase of approximately ten field sales
representatives and increases in sales commissions. As a percentage of sales
from continuing operations, selling expenses declined from 15.9% in the second
quarter of 1998 to 15.1% in the second quarter of 1999.

For the six months ended June 30, 1999, selling expenses increased 13.9% or $1.2
million to $9.5 million. The increase primarily resulted from the increase in
the number of field sales representatives and increases in sales commissions
discussed above. As a percentage of sales from continuing operations, selling
expenses declined from 16.5% for the six months ended June 30, 1998 to 15.7% for
the six months ended June 30, 1999.

General and administrative expenses remained relatively unchanged at $2.7
million for the second quarter of 1999 vs. $2.6 million for the second quarter
of 1998. For the six months ended June 30, 1999, general and administrative
expenses increased $.6 million to $5.3 million, from $4.7 million in 1998. The
increase in 1999 over 1998 resulted from increases in license fees, bonuses, and
depreciation. As a percentage of sales from continuing operations, general and
administrative expenses decreased from 9.3% in 1998 to 8.6% in 1999.

The nonrecurring charge of $10.5 million in 1998 related to the write-down of
goodwill associated with certain lower-margin pharmaceutical products. As a
result of this goodwill write-down, amortization expense in 1999 has been
reduced by approximately $.1 million per quarter.


OPERATING INCOME FROM CONTINUING OPERATIONS

Excluding the effect of the $10.5 million nonrecurring charge in 1998, operating
income from continuing operations increased $4.9 million or 39.2% during the
second quarter of 1999 as compared to the second quarter of 1998. For the six
months ended June 30, 1999, operating income from continuing operations
increased $8.4 million or 35.9% over the same period of 1998, excluding the
effect of the 1998 nonrecurring charge.






                                       13
<PAGE>   14

OTHER INCOME (EXPENSE)

Other income increased during the three months and six months ended June 30,
1999 as compared to the same periods of 1998 primarily due to the increase in
interest income earned on the additional invested cash balances generated from
the $55 million of proceeds from the sale of the Company's Nutritional Business
on April 30, 1998 and positive cash flow from operations.

INCOME TAXES

The provisions for income taxes for the three month and six month periods ended
June 30, 1999 are based on estimated effective annual income tax rates of 39.0%
and 38.8%, respectively. For the three month and six month periods ended June
30, 1998, the provisions for income taxes reflect the nondeductibility of the
$10.5 million nonrecurring charge. Excluding the effects of the nonrecurring
charge in 1998, the estimated effective income tax rate approximates 38.5%.

INCOME FROM CONTINUING OPERATIONS

Excluding the effect of the nonrecurring charge in 1998, income from continuing
operations for the second quarter of 1999 increased $3.1 million to $11.6
million and for the six months ended June 30, 1999, increased $5.6 million to
$21.4 million.

INCOME FROM DISCONTINUED OPERATIONS

Income from discontinued operations in 1998 includes an approximate $17 million
(net of tax) gain from the sale of the Company's Nutritional Business on April
30, 1998. In addition, income from discontinued operations includes the
after-tax operating results of the Company's discontinued businesses prior to
the sale of the Nutritional Business on April 30, 1998.

EARNINGS PER SHARE

After giving retroactive effect to a three-for-two stock split declared July 13,
1999, diluted earnings per share from continuing operations totaled $.26 and
$.48 for the quarter and six months ended June 30, 1999 as compared to $.19 and
$.36 for the same periods of 1998, excluding the $10.5 million after-tax
nonrecurring charge. The earnings per share increases represent net income
growth computed on relatively flat average shares outstanding.

BALANCE SHEET INFORMATION

The Company's current ratio decreased from 13.1:1 as of December 31, 1998 to
11.7:1 as of June 30, 1999 although working capital increased to $163.9 million
at June 30, 1999 from $142.3 million at December 31, 1998 primarily due to an
increase in cash generated from positive operating cash flow.

LIQUIDITY AND CAPITAL RESOURCES

Since inception the Company has financed its operations primarily through cash
flow from operations, public and private sales of equity securities and
borrowings under revolving credit facilities. At June 30, 1999 and December 31,
1998, the Company had cash and cash equivalents of $148.3 million and $122.7
million, respectively. The Company believes that available resources and
anticipated cash flows from operations are adequate to meet currently
anticipated operating




                                       14
<PAGE>   15

needs and to fund future acquisitions. While the Company does not maintain
current lines of credit, it believes it has sufficient borrowing capacity in the
event that acquisition opportunities cannot be funded from existing resources.

Total assets increased $23.4 million to $272.2 million at June 30, 1999 from
$248.8 million at December 31, 1998 primarily due to the increase in cash
discussed above. Total liabilities increased $3.6 million to $19.7 million at
June 30, 1999 from $16.1 million at December 31, 1998 primarily due to the
increase in income taxes payable.

Inventories increased to $10.6 million at June 30, 1999 compared to $7.5 million
at December 31, 1998 due to planned quantity build-ups of Levoxyl and
JMI-Thrombin. Accounts receivable decreased to $14.9 million at June 30, 1999
from $19.1 million at December 31, 1998 due to higher sales levels in the month
of December 1998 vs. the month of June 1999, and due to the Company's
concentrated effort on improving collections. In days outstanding, accounts
receivable decreased from 60 days at December 31, 1998 to 51 days at June 30,
1999.

The Company has experienced only moderate raw material and labor price increases
in recent years. While the Company has passed some price increases along to
customers, the Company has primarily benefited from rapid sales growth, negating
most inflationary pressures. The Company's manufacturing operations are not
capital intensive and, as such, the impact of inflation on the property, plant,
and equipment and associated depreciation expense of the Company has been
minimal.

YEAR 2000 UPDATE

The Year 2000 issue exists because many computer systems and applications,
including those embedded in equipment and facilities, use two digit rather than
four digit date fields to designate an applicable year. As a result, the systems
and applications may not properly recognize the year 2000 or process data that
includes it, potentially causing data miscalculations or inaccuracies or
operational malfunctions or failures. The inability to accurately process date
related information would have a material impact on the Company's operations and
financial condition. To mitigate the risks of a Year 2000 failure, a Year 2000
action plan (the "Plan") has been developed and is currently being executed by
the Company. The Plan is directed and monitored by the Company's Information
Technology (IT) Steering Committee and is proceeding within the planned
timetable. The Plan addresses the Year 2000 risk presented by the following IT
and non-IT elements of the Company's operations.

Specifically, the Plan addresses Year 2000 issues in the following areas:

     Information Technology Infrastructure

     The Company has completed the replacement of its software and systems in
     the normal course of business. The financial system has been replaced with
     an Enterprise Reporting System that the developer states is Year 2000
     compliant. Assessment of all other hardware and software is complete and
     remediation and testing is currently underway with an expected completion
     date of August 30, 1999.

     Business Infrastructure

     The Company's review in this area includes such things as security,
     utilities, environmental control systems, telephones, facsimile machines,
     manufacturing, laboratory and shipping




                                       15
<PAGE>   16

     equipment. Efforts in this area, including compliance validation with
     vendors, remediation and testing, are expected to be completed by September
     30, 1999.

     External Interfaces

     This area of review includes all Company interfaces with external service
     agencies such as purchased information sources, payroll processing,
     benefits processing, insurance and investments, health claims and banking.
     The Company is substantially complete with its efforts to secure third
     party compliance statements in assessing the compliance status of our
     external interfaces.

     Supplier and Customer Readiness

     The Company is highly dependent on internal and third-party computer
     systems to process its daily transactions. The Company has commenced
     efforts to determine the extent to which it may be impacted by Year 2000
     issues of third parties, including suppliers, and customers. Contact with
     major customers and suppliers has been initiated and responses have been
     received from approximately 50 percent of those solicited. The Company
     plans to follow-up with those that have not responded by August 15, 1999.
     To date, the Company is not aware of any non-Year 2000 compliant
     third-party customers or suppliers that would materially impact the
     Company's results of operations, liquidity, or capital resources.

     However, the Company has no means of ensuring these entities will be Year
     2000-ready. Furthermore, the Company has no means of ensuring the customers
     of its wholesale distributors (e.g., hospital buying groups, hospitals and
     pharmacies) will be Year 2000-ready. The inability of third parties to
     complete their Year 2000 programs in a timely manner could materially
     impact the Company. Given the Company's reliance upon third-party
     manufacturers for the supply of certain key products, the Company has made
     arrangements to purchase 3 to 6 month supplies of Brevital, Tapazole and
     Cytomel in the fourth quarter of 1999.

     Contingency Plan

     Contingency plans for the Company are being developed to minimize business
     risks in case of local and/or regional Year 2000-related failures. The
     Company is in the process of developing contingency plans for each of its
     manufacturing and distribution facilities as well as the corporate
     operation. Such plans are expected to be completed by September 30, 1999.

The costs associated with the Company's Year 2000 Plan have, for the most part,
been planned capital expenditures and budgeted internal staffing expenses. The
total capital expenditures related to these system upgrades and/or replacements
approximate $1.5 million and have been capitalized as incurred. Additional costs
to be incurred to complete the Plan are not expected to be significant and will
relate to the ongoing capital expenditures and internal staffing described
above.

The failure to correct a material Year 2000 problem could result in an
interruption in, or failure of, certain normal business activities or
operations. Such failure could materially and adversely impact the Company's
results of operations, liquidity, and financial condition. Although the Company
has not yet developed a comprehensive contingency plan to address situations
that may result if the Company or any of the third parties upon which the
Company is dependent is unable to achieve Year 2000 readiness, a plan will be
completed by the fourth quarter of 1999 to



                                       16
<PAGE>   17
address the most reasonably likely worst-case scenario with respect to potential
Year 2000 compliance failures. Based on the Company's progress to date and
timeline to complete the Year 2000 Plan, the Company does not foresee
significant financial or operational risks associated with its compliance at
this time. However, these expectations are subject to uncertainties including,
but not limited to, the readiness of third-party customers, suppliers, and
service providers, failure to identify all susceptible systems, and the
availability and cost of personnel necessary to address any unforeseen problems.



































                                       17
<PAGE>   18

                           PART II - OTHER INFORMATION


Item 4.   Submission of Matters to a Vote of Security Holders

     The Annual Meeting of Shareholders of JONES PHARMA INCORPORATED was held on
May 17, 1999. At the Annual Meeting, each of the nine nominees to the Board of
Directors was elected for a one-year term by the shareholders:

<TABLE>
<CAPTION>

                                                                  WITHHELD OR
             DIRECTOR                           FOR                 ABSTAIN
             --------                           ---                 -------
<S>                                          <C>                    <C>
         Dennis M. Jones                     22,752,845             158,428

         Judith A. Jones                     22,748,965             162,308

         Michael T. Bramblett                22,753,055             158,218

         G. Andrew Franz                     22,751,990             159,283

         David A. McLaughlin                 22,753,450             157,823

         J. Hord Armstrong, III              22,746,025             165,248

         L. John Polite, Jr.                 22,760,791             150,482

         Edward A. Chod                      22,752,355             158,918

         Thomas F. Patton, Ph.D.             22,764,225             147,048
</TABLE>


Item 5.   Other Information

     On July 13, 1999, the Board of Directors of the Company adopted an
incentive stock plan known the 1999 Equity Participation Plan for Non-Management
Directors (the "1999 Equity Participation Plan"). The purpose of the 1999 Equity
Participation Plan is to provide certain long-term equity incentives to eligible
directors of the Company in order to encourage the highest level of performance
of non-management directors by providing those directors with a proprietary
interest in the Company's success and progress through grants of options to
purchase shares of the Company's Common Stock and other equity-based awards in
accordance with the terms and conditions set forth in the 1999 Equity
Participation Plan. A copy of the 1999 Equity Participation Plan is included as
an exhibit to this Form 10-Q.










                                       18
<PAGE>   19




Item 6.   Exhibits and Report on Form 8-K


     (a)  Exhibits

          (10) 1999 Equity Participation Plan for Non-Management Directors.


          (22) The Company's proxy statement dated April 8, 1999, containing the
               full text of the proposals referred to in Item 4 of Part II of
               this Form 10-Q, which was previously filed electronically, is
               hereby incorporated by reference.


          (27) Financial Data Schedule.


     (b)  Reports on Form 8-K

          NONE












                                       19

<PAGE>   20




                                   SIGNATURES



Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                      JONES PHARMA INCORPORATED



Date:    August 6, 1999               By:/s/ Dennis M. Jones
     -------------------------           -------------------------------
                                         Dennis M. Jones, President




Date:    August 6, 1999               By: /s/ Judith A. Jones
     -------------------------            ------------------------------
                                          Judith A. Jones
                                          Executive Vice President and
                                          Principal Financial and
                                          Accounting Officer























                                       20