<PAGE>   1
                                                                   EXHIBIT 10.28

                          ALLERGY SUPERSTORE.COM, INC.

                        1999 DIRECTORS STOCK OPTION PLAN

                       As Adopted _________________, 1999


         1. PURPOSE. This 1999 Directors Stock Option Plan (this "PLAN") is
established to provide equity incentives for certain nonemployee members of the
Board of Directors of Allergy Superstore.com, Inc. (the "COMPANY"), who are
described in Section 6.1 below, by granting such persons options to purchase
shares of stock of the Company.

         2. ADOPTION AND STOCKHOLDER APPROVAL. This Plan will become effective
upon the adoption by the Board of Directors (the "BOARD") of the Company (the
"EFFECTIVE DATE"). This Plan shall be approved by the stockholders of the
Company, consistent with applicable laws, within twelve (12) months after the
date this Plan is adopted by the Board.

         3. TYPES OF OPTIONS AND SHARES. Options granted under this Plan shall
be non-qualified stock options ("NQSOS"). The shares of stock that may be
purchased upon exercise of Options granted under this Plan (the "SHARES") are
shares of the Common Stock of the Company.

         4. NUMBER OF SHARES. The maximum number of Shares that may be issued
pursuant to Options granted under this Plan (the "MAXIMUM NUMBER") is 2,000,000
Shares, subject to adjustment as provided in this Plan. If any Option is
terminated for any reason without being exercised in whole or in part, the
Shares thereby released from such Option shall be available for purchase under
other Options subsequently granted under this Plan. At all times during the term
of this Plan, the Company shall reserve and keep available such number of Shares
as shall be required to satisfy the requirements of outstanding Options granted
under this Plan; provided, however that if the aggregate number of Shares
subject to outstanding Options granted under this Plan plus the aggregate number
of Shares previously issued by the Company pursuant to the exercise of Options
granted under this Plan equals or exceeds the Maximum Number, then
notwithstanding anything herein to the contrary, no further Options may be
granted under this Plan until the Maximum Number is increased or the aggregate
number of Shares subject to outstanding Options granted under this Plan plus the
aggregate number of Shares previously issued by the Company pursuant to the
exercise of Options granted under this Plan is less than the Maximum Number.

         5. ADMINISTRATION. This Plan shall be administered by the Board or by a
committee of not less than two members of the Board appointed to administer this
Plan (the "COMMITTEE"). As used in this Plan, references to the Committee shall
mean either such Committee or the Board if no Committee has been established.
The


<PAGE>   2


interpretation by the Committee of any of the provisions of this Plan or any
Option granted under this Plan shall be final and binding upon the Company and
all persons having an interest in any Option or any Shares purchased pursuant to
an Option.

         6. ELIGIBILITY AND AWARD FORMULA.

         6.1 Eligibility. Options shall be granted only to directors of the
Company who are not employees of the Company or any Parent, Subsidiary or
Affiliate of the Company, as those terms are defined in Section 17 below (each
such person referred to as an "OPTIONEE").

         6.2 Initial Grant. Each Optionee who first becomes a member of the
Board on or after the Effective Date will automatically be granted an Option for
30,000 Shares (an "INITIAL GRANT") on the earlier of the Effective Date or on
the date such Optionee first becomes a member of the Board.

         6.3 Succeeding Grants. At each Annual Meeting of the Company, each
Optionee will automatically be granted an Option for 5,000 Shares (a "SUCCEEDING
GRANT"), provided the Optionee is a member of the Board on such date and has
served continuously as a member of the Board since the date of such Optionee's
Initial Grant or, if such Optionee was ineligible to receive an Initial Grant,
since the Effective Date.

         7. TERMS AND CONDITIONS OF OPTIONS. Subject to the following and to
Section 6 above:

         7.1 Form of Option Grant. Each Option granted under this Plan shall be
evidenced by a written Stock Option Grant ("GRANT") in such form (which need not
be the same for each Optionee) as the Committee shall from time to time approve,
which Grant shall comply with and be subject to the terms and conditions of this
Plan.

          7.2 Vesting. The date an Optionee receives an Initial Grant or a
Succeeding Grant is referred to in this Plan as the "START DATE" for such
Option.

               (a) Initial Grants. Each Initial Grant will vest as to twenty-
five percent (25%) of the Shares on the first anniversary of the Start Date for
such Initial Grant, and as to 2.08333% of the Shares on each subsequent monthly
anniversary of the Start Date, so long as the Optionee continuously remains a
director or a consultant of the Company.

               (b) Succeeding Grants. Each Succeeding Grant will vest as to
twenty-five percent (25%) of the Shares on the first anniversary of the Start
Date for such Succeeding Grant, and as to 2.08333% of the Shares on each
subsequent monthly anniversary of the Start Date, so long as the Optionee
continuously remains a director or a consultant of the Company.

         7.3 Exercise Price. The exercise price of an Option shall be the Fair
Market Value (as defined in Section 17.4) of the Shares, at the time that the
Option is granted.


<PAGE>   3


         7.4 Termination of Option. Except as provided below in this Section,
each Option shall expire ten (10) years after its Start Date (the "EXPIRATION
DATE"). The Option shall cease to vest when the Optionee ceases to be a member
of the Board or a consultant of the Company. The date on which the Optionee
ceases to be a member of the Board or a consultant of the Company shall be
referred to as the "TERMINATION DATE". An Option may be exercised after the
Termination Date only as set forth below:

               (a) Termination Generally. If the Optionee ceases to be a member
of the Board or a consultant of the Company for any reason except death of the
Optionee or disability of the Optionee (whether temporary or permanent, partial
or total, as determined by the Committee), then each Option then held by such
Optionee, to the extent (and only to the extent) that it would have been
exercisable by the Optionee on the Termination Date, may be exercised by the
Optionee no later than seven (7) months after the Termination Date, but in no
event later than the Expiration Date.

               (b) Death or Disability. If the Optionee ceases to be a member of
the Board or a consultant of the Company because of the death of the Optionee or
the disability of the Optionee (whether temporary or permanent, partial or
total, as determined by the Committee), then each Option then held by such
Optionee to the extent (and only to the extent) that it would have been
exercisable by the Optionee on the Termination Date, may be exercised by the
Optionee (or the Optionee's legal representative) no later than twelve (12)
months after the Termination Date, but in no event later than the Expiration
Date.

         8. EXERCISE OF OPTIONS.

         8.1 Exercise Period. Subject to the provisions of Section 8.5 below,
Options shall be exercisable as they vest; provided that the Committee may
provide that such Options shall be immediately exercisable subject to repurchase
in accordance with the vesting schedule set forth in Section 7.

         8.2 Notice. Options may be exercised only by delivery to the Company of
an exercise agreement in a form approved by the Committee stating the number of
Shares being purchased, the restrictions imposed on the Shares and such
representations and agreements regarding the Optionee's investment intent and
access to information as may be required by the Company to comply with
applicable securities laws, together with payment in full of the exercise price
for the number of Shares being purchased.

         8.3 Payment. Payment for the Shares purchased upon exercise of an
Option may be made (a) in cash or by check; (b) by surrender of shares of Common
Stock of the Company that have been owned by the Optionee for more than six (6)
months (and which have been paid for within the meaning of SEC Rule 144 and, if
such shares were purchased from the Company by use of a promissory note, such
note has been fully paid with respect to such shares) or were obtained by the
Optionee in the open public market, having a Fair Market Value equal to the
exercise price of the Option; (c) by waiver of 


<PAGE>   4


compensation due or accrued to the Optionee for services rendered; (d) provided
that a public market for the Company's stock exists, through a "same day sale"
commitment from the Optionee and a broker-dealer that is a member of the
National Association of Securities Dealers (an "NASD DEALER") whereby the
Optionee irrevocably elects to exercise the Option and to sell a portion of the
Shares so purchased to pay for the exercise price and whereby the NASD Dealer
irrevocably commits upon receipt of such Shares to forward the exercise price
directly to the Company; (e) provided that a public market for the Company's
stock exists, through a "margin" commitment from the Optionee and an NASD Dealer
whereby the Optionee irrevocably elects to exercise the Option and to pledge the
Shares so purchased to the NASD Dealer in a margin account as security for a
loan from the NASD Dealer in the amount of the exercise price, and whereby the
NASD Dealer irrevocably commits upon receipt of such Shares to forward the
exercise price directly to the Company; or (f) by any combination of the
foregoing.

         8.4 Withholding Taxes. Prior to issuance of the Shares upon exercise of
an Option, the Optionee shall pay or make adequate provision for any federal or
state withholding obligations of the Company, if applicable.

         8.5 Limitations on Exercise. Notwithstanding the exercise periods set
forth in the Grant, exercise of an Option shall always be subject to the
following limitations:

               (a) An Option shall not be exercisable unless such exercise is in
compliance with the Securities Act and all applicable state securities laws, as
they are in effect on the date of exercise.

               (b) The Committee may specify a reasonable minimum number of
Shares that may be purchased upon any exercise of an Option, provided that such
minimum number will not prevent the Optionee from exercising the full number of
Shares as to which the Option is then exercisable.

         9. NONTRANSFERABILITY OF OPTIONS. During the lifetime of the Optionee,
an Option shall be exercisable only by the Optionee or by the Optionee's
guardian or legal representative, unless otherwise determined by the Committee.
No Option may be sold, pledged, assigned, hypothecated, transferred or disposed
of in any manner other than by will or by the laws of descent and distribution,
unless otherwise determined by the Committee.

         10. PRIVILEGES OF STOCK OWNERSHIP. No Optionee shall have any of the
rights of a stockholder with respect to any Shares subject to an Option until
the Option has been validly exercised. No adjustment shall be made for dividends
or distributions or other rights for which the record date is prior to the date
of exercise, except as provided in this Plan. The Company shall provide to each
Optionee a copy of the annual financial statements of the Company at such time
after the close of each fiscal year of the Company as they are released by the
Company to its stockholders.


<PAGE>   5


         11. ADJUSTMENT OF OPTION SHARES. In the event that the number of
outstanding shares of Common Stock of the Company is changed by a stock
dividend, stock split, reverse stock split, combination, reclassification or
similar change in the capital structure of the Company without consideration,
the number of Shares available under this Plan and the number of Shares subject
to outstanding Options and the exercise price per share of such outstanding
Options shall be proportionately adjusted, subject to any required action by the
Board or stockholders of the Company and compliance with applicable securities
laws; provided, however, that no fractional shares shall be issued upon exercise
of any Option and any resulting fractions of a Share shall be rounded up to the
nearest whole Share.

         12. NO OBLIGATION TO CONTINUE AS DIRECTOR. Nothing in this Plan or any
Option granted under this Plan shall confer on any Optionee any right to
continue as a director of the Company.

         13. COMPLIANCE WITH LAWS. The grant of Options and the issuance of
Shares upon exercise of any Options shall be subject to and conditioned upon
compliance with all applicable requirements of law, including without limitation
compliance with the Securities Act, compliance with all other applicable state
securities laws and compliance with the requirements of any stock exchange or
national market system on which the Shares may be listed. The Company shall be
under no obligation to register the Shares with the SEC or to effect compliance
with the registration or qualification requirement of any state securities laws,
stock exchange or national market system.

         14. ACCELERATION OF OPTIONS ON CERTAIN CORPORATE TRANSACTIONS. In the
event of (a) a dissolution or liquidation of the Company, (b) a merger or
consolidation in which the Company is not the surviving corporation (other than
a merger or consolidation with a wholly-owned subsidiary, a reincorporation of
the Company in a different jurisdiction, or other transaction in which there is
no substantial change in the stockholders of the Company or their relative stock
holdings and the Options granted under this Plan are assumed, converted or
replaced by the successor corporation, which assumption, conversion or
replacement will be binding on all Optionees), (c) a merger in which the Company
is the surviving corporation but after which the stockholders of the Company
(other than any stockholder which merges (or which owns or controls another
corporation which merges) with the Company in such merger) cease to own their
shares or other equity interests in the Company, (d) the sale of substantially
all of the assets of the Company, or (e) the acquisition, sale or transfer of
more than 50% of the outstanding shares of the Company by tender offer or
similar transaction, the vesting of all options granted pursuant to this Plan
will accelerate and the options will become exercisable in full prior to the
consummation of such event at such times and on such conditions as the Committee
determines, and must be exercised, if at all, within seven months of the
consummation of said event. Any options not exercised within such seven-month
period shall expire.



<PAGE>   6


         15. AMENDMENT OR TERMINATION OF PLAN. The Board may at any time
terminate or amend this Plan or any outstanding option, provided that the Board
may not terminate or amend the terms of any outstanding option without the
consent of the Optionee. In any case, no amendment of this Plan may adversely
affect any then outstanding Options or any unexercised portions thereof without
the written consent of the Optionee.

         16. TERM OF PLAN. Options may be granted pursuant to this Plan from
time to time within a period of ten (10) years from the Effective Date.

         17. CERTAIN DEFINITIONS. As used in this Plan, the following terms
shall have the following meanings:

         17.1 "PARENT" means any corporation (other than the Company) in an
unbroken chain of corporations ending with the Company if each of such
corporations other than the Company owns stock possessing 50% or more of the
total combined voting power of all classes of stock in one of the other
corporations in such chain.

         17.2 "SUBSIDIARY" means any corporation (other than the Company) in an
unbroken chain of corporations beginning with the Company if each of the
corporations other than the last corporation in the unbroken chain owns stock
possessing 50% or more of the total combined voting power of all classes of
stock in one of the other corporations in such chain.

         17.3 "AFFILIATE" means any corporation that directly, or indirectly
through one or more intermediaries, controls or is controlled by, or is under
common control with, another corporation, where "control" (including the terms
"controlled by" and "under common control with") means the possession, direct or
indirect, of the power to cause the direction of the management and policies of
the corporation, whether through the ownership of voting securities, by contract
or otherwise.

         17.4 "FAIR MARKET VALUE" means, as of any date, the value of a share of
the Company's Common Stock determined as follows:

         (a) if such Common Stock is then quoted on the Nasdaq National Market,
its closing price on the Nasdaq National Market on the date of determination as
reported in The Wall Street Journal;

         (b) if such Common Stock is publicly traded and is then listed on a
national securities exchange, its closing price on the date of determination on
the principal national securities exchange on which the Common Stock is listed
or admitted to trading as reported in The Wall Street Journal;


<PAGE>   7


         (c) if such Common Stock is publicly traded but is not quoted on the
Nasdaq National Market nor listed or admitted to trading on a national
securities exchange, the average of the closing bid and asked prices on the date
of determination as reported in The Wall Street Journal;

         (d) in the case of an Option granted on the Effective Date, the price
per share at which shares of the Company's Common Stock are initially offered
for sale to the public by the Company's underwriters in the initial public
offering of the Company's Common Stock pursuant to a registration statement
filed with the SEC under the Securities Act; or

         (e) if none of the foregoing is applicable, by the Committee in good
faith.