<PAGE>

                                                                     Exhibit 4.3

                             ROTECH HEALTHCARE INC.
                            COMMON STOCK OPTION PLAN

     1. Purpose.
        -------

          The purpose of the Rotech Healthcare Inc. Common Stock Option Plan
(the "Plan") is to enhance the ability of Rotech Healthcare Inc. (the "Company")
to attract and retain employees, officers, consultants and nonemployee members
of the Board of Directors of the Company of outstanding ability, and provide
them with an interest in the growth and continued success of the Company by
granting them Options to purchase shares of the Company's common stock

     2. Definitions.
        -----------

          Whenever the following terms are used in this Plan, they shall have
the meaning specified below unless the context clearly indicates to the
contrary.

          "Board" shall mean the Board of Directors of the Company or a
           ------
committee thereof, including any compensation committee created by the Board of
Directors.

          "Cause" shall mean (i) a Participant's gross neglect of or willful
           ------
failure to perform his or her material duties with the Company, which neglect or
failure shall continue for a period of two (2) days after receipt by Participant
of written notice from the Company directing such Participant to perform his or
her material duties, (ii) a Participant's willful engaging in conduct which is
materially injurious to the Company or any subsidiary, which injury shall not
have been remedied with two (2) days after receipt by Participant of written
notice from the Company of the injury caused by such conduct, (iii) a
Participant's theft or misappropriation of funds of the Company, or any
subsidiary, (iv) a Participant's conviction of, or plea of nolo contendere to, a
felony or a misdemeanor involving moral turpitude, or (v) a Participant's
causing the Company to violate a local, state or federal law where such
violation is materially injurious to the Company; provided, that if the
Participant has entered into an agreement with the Company, the Board shall
substitute the definition of Cause set forth in such agreement for the above.

          "Change in Control" shall mean the occurrence of any of the following:
           ------------------

          (a) any Person (other than the Company or any subsidiary or any
trustee or other fiduciary holding securities under an employee benefit plan of
the Company), becomes the beneficial owner (within the meaning of Rule l3d-3
under the Exchange Act) directly or indirectly, of securities of the Company
representing fifty percent (50%) or more of the combined voting power of the
Company's then outstanding securities;

          (b) during any two consecutive years, individuals who at the beginning
of such period constitute the Board, and any new director (whose election by the
Board or nomination for election by the Company's shareholders was approved by a
vote of at least two-thirds (2/3) of the directors then still in office who
either were directors at the beginning of the

<PAGE>


period or whose election or nomination for election was previously so approved),
cease for any reason to constitute at least a majority of the Board;

          (c) the stockholders of the Company approve a merger or consolidation
of the Company with any other company other than (i) a merger or consolidation
which would result in the voting securities of the Company outstanding
immediately prior thereto continuing to represent (either by remaining
outstanding or by being converted into voting securities of the surviving
entity) more than fifty percent (50%) of the combined voting power of the voting
securities of the Company (or such surviving entity) outstanding immediately
after such merger or consolidation, or (ii) a merger or consolidation effected
to implement a recapitalization of the Company (or similar transaction) in which
no "person" (as hereinafter defined) acquires more than fifty percent (50%) of
the combined voting power of the Company's then outstanding securities; or

          (d) the stockholders of the Company adopt a plan of complete
liquidation of the Company or an agreement for the sale or disposition by the
Company of all or substantially all of the Company's assets.

          "Code" shall mean the Internal Revenue Code of 1986, as amended.
           -----

          "Company" shall mean Rotech Healthcare Inc., a Delaware corporation,
           --------
and any successor corporation.

          "Disability" shall mean the inability to engage in any substantial
           -----------
gainful activity by reason of any medically determined physical or mental
impairment which can be expected to result in death or which has lasted or can
be expected to last for a continuous period of not less than twelve (12) months.

          "Exchange Act" shall mean the Securities Exchange Act of 1934, as
           -------------
amended.

          "Fair Market Value" per Share as of a particular date shall mean,
           ------------------
unless otherwise determined by the Board:

               (i) the closing sales price per Share on a national securities
exchange for the business day preceding the exercise date on which there was a
sale of Shares on such exchange;

               (ii) if clause (i) does not apply and the Shares are then quoted
on the National Association of Securities Dealers Automated Quotation system
(known as "NASDAQ"), the closing price per Share as reported on such system for
the business day preceding the exercise date on which a sale was reported;

               (iii) if clause (i) or (ii) does not apply and the Shares are
then traded on an over-the-counter market, the closing price for the Shares in
such over-the-counter market for the business day preceding the exercise date;
or

                                      -2-

<PAGE>

               (iv) if the Shares are not then listed on a national securities
exchange or traded in an over-the-counter market, such value as the Board in its
sole discretion may reasonably determine.

          "Immediate Family Member" shall include any child, stepchild,
           ------------------------
grandchild, parent, stepparent, grandparent, spouse, former spouse, sibling,
niece, nephew, mother-in-law, father-in-law, son-in-law, daughter-in-law,
brother-in-law, or sister-in-law, including adoptive relationships, any person
sharing the Participant's household (other than a tenant or employee), a trust
in which these persons have more than fifty percent (50%) of the beneficial
interest, a foundation in which these persons (or the Participant) control the
management of assets, and any other entity in which these persons (or the
Participant) own more than fifty percent (50%) of the voting interests.

          "Incentive Stock Option" shall mean an Option intended to meet the
           -----------------------
requirements of Section 422 of the Code.

          "Initial Public Offering" shall mean the consummation of the first
           ------------------------
underwritten public offering of the Company's Shares for the account of the
Company pursuant to a registration statement (other than on Form S-4 or Form
S-8 or successor forms) filed with, and declared effective by, the United States
Securities Exchange Commission.

          "Nonqualified Stock Option" shall mean any option which is not an
           --------------------------
Incentive Stock Option.

          "Option" shall mean an option to purchase Shares granted pursuant to
           -------
the Plan.

          "Option Agreement" shall mean an Option Agreement between the Company
           -----------------
and any Participant, which shall set forth the terms and conditions of the
Option granted to such Participant.

          "Participant" shall mean any Person who is granted an Option under the
           ------------
Plan.

          "Person" shall have the meaning set forth in Sections 13(d) and 14(d)
           -------
of the Exchange Act.

          "Share" shall mean a share of the Company's common stock, $0.0001 par
           ------
value.

          "Ten Percent Shareholder" shall mean any Participant who owns Shares
           ------------------------
possessing more than ten percent (10%) of the total combined voting power of all
classes of stock of the Company or any parent or subsidiary corporation within
the meaning of Section 424 of the Code.

     3. Shares Subject to the Plan.
        --------------------------

          (a) Shares Subject to the Plan. Subject to adjustment as set forth in
              --------------------------
Section 3(b), the maximum number of Shares that may be issued or transferred
pursuant to Options under this Plan shall be three million twenty-five thousand
(3,025,000) which may be authorized but unissued Shares or Shares held in the
Company's treasury, or a combination thereof. Any Shares

                                      -3-

<PAGE>

subject to an Option that cease to be subject thereto may again be the subject
of Options hereunder. Subject to adjustment in accordance with Section 3(b), no
Participant shall be granted in any calendar year Options to purchase more than
six hundred thousand (600,000) Shares solely for such time as the Company is
subject to Section 162(m) of the Code.

          (b) Changes in Company's Shares. In the event that any stock dividend,
              ---------------------------
extraordinary cash dividend, recapitalization, reorganization, merger,
consolidation, split-up, spin-off, combination, exchange of shares, warrants or
rights offering to purchase Shares, or other similar corporate event, affects
the value of the Shares such that an adjustment is required in order to preserve
the benefits or potential benefits intended to be made available under this
Plan, the Board shall adjust any or all of (a) the number and kind of Shares
subject to outstanding Options, and (b) the exercise price with respect to any
Option or (c) make provision for a cash payment to any Participant or a person
who has an outstanding Option (in an amount equal to the then difference between
the exercise price and the Fair Market Value of a Share) in order to preserve
such benefits.

     4. Participation.
        -------------

          Each employee, officer and nonemployee director of, and each
consultant to, the Company shall be eligible to participate in the Plan,
provided that the Board shall have the discretion to determine who shall receive
a grant of Options hereunder and become a Participant.

     5. Terms of Options and Shares.
        ---------------------------

          (a) Terms. The Options granted hereunder shall have the following
              -----
terms and conditions:

               (i) Type of Option. The Board shall have the right to grant
                   --------------
either or both of Incentive Stock Options and Nonqualified Stock Options, which
characterization shall be set forth in the Option Agreement; provided, however,
that Incentive Stock Options shall only be granted to employees of the Company,
and provided further that no employee shall be granted Incentive Stock Options
which, when first exercisable during any calendar year (combined with all other
incentive stock option plans of the Company), will permit such employee to
purchase Shares that have an aggregate Fair Market Value (determined as of the
time the Option is granted) of more than $100,000 and any Option granted in
excess of such amount shall automatically be deemed to be a Nonqualified Stock
Option.

               (ii) Exercise Price. The exercise price of any Option shall be
                    --------------
one hundred percent (100%) of the Fair Market Value of a Share as of the date
the Option is granted; provided, however, that (1) the Board, in its sole
discretion, may grant Nonqualified Stock Options with an exercise price above or
below Fair Market Value, and (2) the exercise price of any incentive Stock
Option granted to a Ten Percent Shareholder shall be no less than one hundred
and ten percent (110%) of the Fair Market Value of a Share on the date of grant.
It is contemplated by the Company that each Company Share will have a value of
approximately nineteen dollars ($19.00) upon the occurrence of the effective
date of the Amended Joint Plan of Reorganization of Rotech Medical Corporation
and its Subsidiaries Under Chapter 11 of the

                                      -4-

<PAGE>

Bankruptcy Code filed by the Company with the United States District Court for
the District of Delaware on December 20, 2001.

               (iii) Term. Subject to the discretion of the Board, the term of
                     ----
an Option shall not exceed ten years (10) from the date it is granted; provided,
however, that in the case of Incentive Stock Options granted to a Ten Percent
Shareholder, the term of such Option shall not exceed five (5) years from the
date of grant.

               (iv) Vesting. An Option shall become exercisable (a) with respect
                    -------
to one-quarter (25%) of the original aggregate number of Shares purchasable upon
exercise of such Option on each of the first four anniversaries of the date it
is granted, (b) one-half (50%) to one hundred percent (100%) of the Shares under
such Option upon a Change in Control, such percentage to be determined at the
sole discretion of the Board, and (c) one-quarter (25%) of the original
aggregate number of Shares purchasable upon exercise of such Option upon the
consummation of an Initial Public Offering. (For purposes of illustration,
assuming a Participant were granted at the beginning of Year 1 an Option to
purchase one hundred thousand (100,000) Shares and at the end of Year 2 the
Company were to consummate an Initial Public Offering, such Option would vest
and become exercisable as follows: (x) twenty-five thousand (25,000) Shares at
the end of Year 1, (y) twenty-five thousand (25,000) Shares at the end of Year 2
(each as provided in clause (a) above) and (z) an additional twenty-five
thousand (25,000) Shares in Year 2 (as provided in clause (c) above). The
remaining twenty-five thousand (25,000) Shares would vest and become exercisable
at the end of Year 3 (as provided in clause (a) above)) Notwithstanding the
foregoing, in its sole discretion, the Board shall be entitled to substitute a
more accelerated vesting schedule at any time for any Participant.

               (v) Number. Subject to Section 5(a)(i), the Board shall have the
                   -----
discretion to determine the number of Options to be granted to any Participant,
and to determine the terms and conditions of any such grant, all as set forth in
the Option Agreement covering such ,Option.

          (b) (1) Termination of Service. A Participant who ceases to be an
                  ----------------------
employee, officer, nonemployee director or consultant for any reason other than
death, retirement on or after age 65, or Disability shall have forty-five (45)
calender days from the date of such cessation to exercise any then exercisable
Options, after which all such Options shall terminate and be of no further force
or effect; provided, that the Board may determine that the period of exercise
shall be any such other longer period in the Option Agreement. If a Participant
ceases to be an employee, officer, nonemployee director or a consultant due to
death, retirement on or after age 65, or Disability, all outstanding Options
held by such Participant that are exercisable on such date shall remain
exercisable for their term, and shall thereafter terminate and be of no further
force or effect. Any Options that are not exercisable at the time a Participant
ceases to be an employee, officer, director or consultant shall terminate at
such time and be of no further force or effect.

               (2) Puts and Calls Following Termination of Employment.
                   --------------------------------------------------
Notwithstanding anything herein to the contrary, so long as there has not been
an Initial Public Offering, in the event a Participant's employment terminates
because of death or Disability, the Participant or such Participant's estate, as
applicable, shall have the right for one (1) year after

                                      -5-

<PAGE>

such death or Disability to sell ("put") all (but not less than all) of his then
exercisable Options and Shares previously issued upon exercise of Options
("Option Shares") to the Company, and the Company shall be obligated to purchase
such Options and Option Shares for an amount in cash, check, or wire transfer
(in each case, after offsetting any amount the Participant is indebted to pay
the Company or any subsidiary as of such time), payable as promptly as possible
following such put, equal to the then Fair Market Value of any Shares (less the
exercise price per Option in the case of Options) for each such Option and
Option Shares. The Company shall have a corresponding privilege in the case of
the Participant's death or Disability, or in the event of his termination of
employment for any reason for the same one (1) year period to compel the
Participant to sell his Options and Option Shares at the same purchase price per
share indicated in the preceding sentence; provided, however, that, in the event
of termination for Cause, the purchase price shall be equal to the lesser of
Fair Market Value and the exercise price. The Company's obligation to honor any
put shall be subject to the Company being permitted to do so under applicable
law and the honoring of any put not violating or resulting in a default or event
of default under the Company's Senior Subordinated Notes due 2012 (or the
indenture under which they were issued) or under the Company's credit agreement
governing the Company's senior secured credit facilities (in either case as they
may be amended).

          (c) Option Agreement. Options shall be granted only pursuant to a
              ----------------
written Option Agreement, which shall be executed by the Participant and an
authorized officer of the Company, and which shall contain such terms and
conditions as the Board shall determine, consistent with the Plan. To the extent
an inconsistency exists between any term of any Option Agreement and any term of
the Plan, the Plan shall govern.

          (d) Nontransferability. No Option granted hereunder shall be
              ------------------
transferable by a Participant to whom granted other than by will or the laws of
descent and distribution, and an Option may be exercised during the lifetime of
such Participant only by a Participant or his guardian or legal representative,
provided, that a Participant may transfer Options that are not Incentive Stock
Options to his or her Immediate Family Members. The terms of such Option shall
be binding upon the Immediate Family Members, beneficiaries, executors,
administrators, heirs and successors of the Participant.

          (e) Method of Exercise. The exercise of an Option shall be made only
              ------------------

by delivery of a written notice (in person or by first class mail to the
Secretary of the Company at the Company's principal executive office) specifying
the number of Shares to be purchased and accompanied by full payment therefor
and otherwise in accordance with the Option Agreement pursuant to which the
Option was granted. The exercise price for any Shares purchased pursuant to the
exercise of an Option shall be paid in full upon such exercise (i) in cash, by
check or, (ii) at the discretion of the Board and upon such terms and conditions
as the Board shall approve, by surrender of Shares that were owned by the
Participant for at least six (6) months prior to the exercise of the Option (or
such longer or shorter period as may be required to not result in a charge to
earnings for financial accounting purposes), (iii) by directing the Company to
subtract from the number of Shares underlying the Option, that number of Shares
having a Fair Market Value equal to the purchase price (or portion thereof)
required to be paid upon such exercise, (iv) solely at a time when the Shares
are publicly-traded, pursuant to a "cashless exercise" of the Option pursuant to
the establishment of procedures whereby the Participant, by a properly executed
written notice, directs (A) an immediate market sale or margin loan respecting
all or a

                                      -6-

<PAGE>

part of the Shares to which he is entitled upon exercise pursuant to an
extension of credit by the Company to the Participant, (B) the delivery of the
Shares from the Company directly to a brokerage firm and (C) the delivery of the
Option price from sale or margin loan proceeds from the brokerage firm directly
to the Company, or (v) by any combination thereof. Any Shares transferred to
the Company as payment of the exercise price shall be valued at their Fair
Market Value on the day preceding the date of exercise of such Option. If
requested by the Board, the Participant shall deliver the Option Agreement
evidencing the Option to the Secretary of the Company who shall endorse thereon
a notation of such exercise and return such Option Agreement to the Participant.
Not less than one hundred (100) Shares may be purchased at any time upon the
exercise of an Option unless the number of Shares so purchased constitutes the
total number of Shares then purchasable under the Option or the Board determines
otherwise in its sole discretion.

          (f) Rights as Stockholder. No Participant shall be deemed for any
              ---------------------
purpose to be or to have the rights and privileges of the owner of any Shares
subject to any Option unless and until (a) the Option shall have been exercised
pursuant to the terms thereof, and (b) the Company shall have issued the Shares
to the Participant.

     6. Administration. The Plan shall be administered by the Board prior to an
        --------------
Initial Public Offering, and following such an Initial Public Offering, unless
and until the Board shall appoint a committee to administer the Plan. All
references to the "Committee" shall mean the Board if no such Committee has been
appointed. Subject to the provisions of the Plan, the Board shall be authorized
to select Participants, determine the type and number of Options, to interpret
and construe the Plan and the Option Agreements, to establish, amend, and
rescind any rules and regulations relating to the Plan, and to make all other
determinations necessary or advisable for the administration of the Plan and to
carry out its purpose. The determinations of the Board (or the Committee) in the
administration of the Plan, as described herein, shall be final, conclusive and
binding. The Secretary of the Company shall be authorized to implement the Plan
in accordance with its terms and to take such actions of a ministerial nature
as shall be necessary to effectuate the intent and purposes thereof.

     7. Other Provisions.
        ----------------

          (a) Effective Date; Grant Limitation. The Plan shall be effective as
              --------------------------------
of the date of effectiveness of the Company's Joint Plan of Reorganization filed
with the United States Bankruptcy Court for the District of Delaware (the
"Effective Date"). No Option to purchase Shares under the Plan shall be granted
to any Participant by the Board after the tenth (10th) anniversary of the
Effective Date.

          (b) Amendment, Suspension or Termination of the Plan. The Plan may be
              ------------------------------------------------
wholly or partially amended or otherwise modified, suspended or terminated at
any time or from time to time by the Board; provided, however, that, except as
provided in Section 3(b) and (d)(ii) of this Section 7, no amendment, suspension
nor termination shall, without the written consent of the Participant, alter or
impair any rights or obligations under any Option theretofore granted.

                                      -7-

<PAGE>

          (c) Governing Law. The Plan and the rights of all persons claiming
              -------------
hereunder shall be construed and determined in accordance with the laws of the
State of Delaware without giving effect to the conflicts of law principles
thereof.

          (d) Regulations and Other Approvals. (i) The obligation of the Company
              -------------------------------
to sell or deliver Shares with respect to Options granted under the Plan shall
be subject to all applicable laws, rules and regulations, including all
applicable federal and state securities laws, and the obtaining of all such
approvals by governmental agencies as may be deemed necessary or appropriate by
the Board.

               (ii) The Board may make such changes as may be necessary or
appropriate to comply with the rules and regulations of any government
authority.

               (iii) Each Option is subject to the requirement that, if at any
time the Board determines, in its sole discretion, that the listing,
registration or qualification of Shares issuable pursuant to the Plan is
required by any securities exchange or under any state or federal law, or the
consent or approval of any governmental regulatory body is necessary or
desirable as a condition of, or in connection with, the grant of an Option or
the issuance of Shares, no Options shall be granted or payment made or Shares
issued, in whole or in part, unless listing, registration, qualification,
consent or approval has been effected or obtained free of any conditions as
acceptable to the Board.

               (iv) In the event that the disposition of Shares acquired
pursuant to the Plan is not covered by a then current registration statement
under the Securities Act of 1933, as amended (the "Securities Act"), and is
not otherwise exempt from such registration, such Shares shall be restricted
against transfer to the extent required by the Securities Act or regulations
there under, and the Board may require any individual receiving Shares pursuant
to the Plan, as a condition precedent to receipt of such Shares, to represent to
the Company in writing that the Shares acquired by such individual are acquired
for investment only and not with a view to distribution. The certificate
representing Shares shall include any legend that the Board deems appropriate to
reflect any restrictions on transfer.

          (e) Withholding of Taxes. As a condition to the exercise of an Option
              --------------------
and to the extent required by law, no later than the date as of which an amount
first becomes includible in the gross income of a Participant for federal income
tax purposes with respect to an Option granted under the Plan, the Participant
shall pay to the Company, or make arrangements satisfactory to the Company
regarding the payment of, any federal, estate, or local taxes of any kind
required by law to be withheld with respect to such amount. The obligations of
the Company under the Plan shall be conditioned on such payment or arrangements,
and the Company shall, to the extent permitted by law, have the right to deduct
any such taxes from any payment of any kind otherwise due to the Participant. In
its discretion, the Board may permit a Participant to satisfy withholding
obligations (i) by delivering previously owned Shares, (ii) by having Shares
withheld or (iii) by cash and any combination of the above.

          (f) Titles; Construction. Titles are provided herein for convenience
              --------------------
only and are not to serve as a basis for interpretation or construction of the
Plan. The masculine pronoun

                                      -8-

<PAGE>

shall include the feminine and neuter and the singular shall include the plural,
when the context so indicates.

                                      -9-