Document:

<PAGE>

                                                                     Exhibit 4.1

COMMON STOCK                                                        COMMON STOCK

  NUMBER                                                               SHARES

DS                               DRUGSTORE.COM

             INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

THIS CERTIFICATE IS TRANSFERABLE IN          SEE REVERSE FOR CERTAIN DEFINITIONS
NEW YORK, NY OR RIDGEFIELD PARK, NJ           AND A STATEMENT AS TO THE RIGHTS,
                                                 PREFERENCES, PRIVILEGES AND
                                                    RESTRICTIONS ON SHARES

                                                      CUSIP 262241 10 2

THIS CERTIFIES THAT

is the record holder of

FULLY PAID AND NON-ASSESSABLE SHARES OF THE COMMON STOCK, $.0001 PAR VALUE PER
                                   SHARE, OF

                              drugstore.com, inc.

transferable on the books of the Corporation by the holder hereof in person or
by duly authorized attorney upon surrender of this Certificate properly
endorsed. This Certificate is not valid until countersigned by the Transfer
Agent and registered by the Registrar.

     WITNESS the facsimile seal of the Corporation and the facsimile signatures
of its duly authorized officers.

Dated:

/s/ Mack Sherman                           /s/ Peter M. Neupert

VICE PRESIDENT, HEALTH SERVICES,                    CHAIRMAN OF THE BOARD,
 GENERAL COUNSEL AND SECRETARY             PRESIDENT AND CHIEF EXECUTIVE OFFICER

                              drugstore.com, inc.
                                   CORPORATE
                                     SEAL
                                     1998
                                 * DELAWARE *

COUNTERSIGNED AND REGISTERED:
   CHASEMELLON SHAREHOLDER SERVICES, LLC.
                 TRANSFER AGENT AND REGISTRAR
BY

                         AUTHORIZED SIGNATURE
<PAGE>

                              drugstore.com, inc.

      A statement of the powers, designations, preferences and relative,
participating, optional or other special rights of each class of stock or series
thereof and the qualifications, limitations or restrictions of such preferences
and/or rights as established, from time to time, by the Certificate of
Incorporation of the Corporation and by any certificate of determination, the
number of shares constituting each class and series, and the designations
thereof, may be obtained by the holder hereof upon request and without charge
from the Secretary of the Corporation at the principal office of the
Corporation.

     The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

     TEN COM  --  as tenants in common
     TEN ENT  --  as tenants by the entireties
     JT TEN   --  as joint tenants with right of
                  survivorship and not as tenants
                  in common
     COM PROP --  as community property

                      UNIF GIFT MIN ACT --               Custodian
                                           -------------           -------------
                                              (Cust)                  (Minor)
                                           under Uniform Gifts to Minors
                                           Act
                                              ----------------------------------
                                                         (State)
                      UNIF TRF MIN ACT --               Custodian (until age   )
                                           ------------                      --
                                              (Cust)
                                                         under Uniform Transfers
                                           -------------
                                              (Minor)
                                           to Minors Act
                                                         -----------------------
                                                                (State)

    Additional abbreviations may also be used though not in the above list.

     FOR VALUE RECEIVED,                   hereby sell, assign and transfer unto
                         -----------------

PLEASE INSERT SOCIAL SECURITY OR OTHER
   IDENTIFYING NUMBER OF ASSIGNEE
--------------------------------------
|                                    |
--------------------------------------

--------------------------------------------------------------------------------
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

                                                                          Shares
-------------------------------------------------------------------------
of the common stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint

                                                                        Attorney
-----------------------------------------------------------------------
to transfer the said stock on the books of the within named Corporation with
full power of substitution in the premises.

Dated
      -----------------------------

                                       X
                                         ---------------------------------------
                                       X
                                         ---------------------------------------
                                 NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT
                                         MUST CORRESPOND WITH THE NAME(S) AS
                                         WRITTEN UPON THE FACE OF THE
                                         CERTIFICATE IN EVERY PARTICULAR,
                                         WITHOUT ALTERATION OR ENLARGEMENT OR
                                         ANY CHANGE WHATEVER.

Signature(s) Guaranteed

By
   --------------------------------
THE SIGNATURE(S) MUST BE GUARANTEED
BY AN ELIGIBLE GUARANTOR INSTITUTION
(BANKS, STOCKBROKERS, SAVINGS AND
LOAN ASSOCIATIONS AND CREDIT UNIONS
WITH MEMBERSHIP IN AN APPROVED
SIGNATURE GUARANTEE MEDALLION
PROGRAM), PURSUANT TO S.E.C. RULE
17Ad-15.<PAGE>

                                                                    Exhibit 10.7

                               FOURTH ADDENDUM TO
            FOURTH AMENDED AND RESTATED INVESTORS' RIGHTS AGREEMENT

     THIS FOURTH ADDENDUM (this "Addendum") dated as of September 29, 2000, to
the Fourth Amended and Restated Investors' Rights Agreement dated as of May 18,
1999 as amended (the "Rights Agreement"), by and among drugstore.com, inc., a
Delaware corporation (the "Company") and the parties listed on Exhibit A hereto,
hereby amends the number of demand registration rights available under the
Rights Agreement. Three prior addenda to the Rights Agreement dated as of June
17, 1999, July 26, 1999 and January 24, 2000 remain in full force and effect.

                                    RECITALS
                                    --------

     A.  The Company has agreed to allow three instead of the currently allowed
two demand registrations under Section 1.2 of the Rights Agreement in exchange
for the agreement by certain of the holders of the registrable securities of the
Company to waive their right to register their shares of Common Stock on the
registration statement on Form S-3 filed by the Company with the Securities and
Exchange Commission on September 6, 2000 (the "Resale Shelf") pursuant to the
Company's agreement to register the 8,101,264 shares of common stock and
4,593,989 shares of common stock issuable upon conversion of the Series 1
Preferred Stock, issued in the private placement that closed on August 4, 2000.

     B.  Pursuant to Section 5.2 of the Rights Agreement, this Addendum is being
executed by the Company and the holders of at least two-thirds (2/3) of the
Registrable Securities presently outstanding, thereby permitting the Rights
Agreement to be amended hereby.

     C.  Capitalized terms used herein and not defined shall have the meanings
given to them in the Rights Agreement.

                                   AGREEMENT
                                   ---------

     1.  This Addendum shall become effective immediately upon the receipt of
the required two-thirds (2/3) consent. Upon such effectiveness:

          (a)  all references in any document to the Rights Agreement shall be
     deemed to be references to the Rights Agreement as modified by this
     Addendum; and

          (b)  except as specifically modified hereby, the Rights Agreement
     shall continue in full force and effect in accordance with the provisions
     thereof.

     2.  Subsection 1.2(d) of the Rights Agreement is hereby amended by deleting
the number "two (2)" appearing in clause (i) thereof and inserting, in lieu
thereof "three (3)".
<PAGE>

                                       2

     3.  This Addendum, which shall be governed, construed and interpreted in
accordance with the laws of the State of California, without giving effect to
principles of conflicts of laws, may be executed in counterparts.

                            [Signature Page Follows]
<PAGE>

                                       3

     The parties have executed this Fourth Addendum to the Fourth Amended and
Restated Investors' Rights Agreement as of the date first above written.

COMPANY:                              INVESTORS:

DRUGSTORE.COM, INC.,                  RITE AID CORPORATION,

By: /s/ Peter M. Neupert              By:  /s/ Elliot S. Gerson
   -------------------------             -------------------------
   Peter M. Neupert                      Name: Elliot S. Gerson
   President                             Title: Sr. Exec. V.P.

   Address:                              Address:
   13920 SE Eastgate Way                 30 Hunter Lane
   Suite 300                             Camp Hill, PA 17011
   Bellevue, WA 98005

                                      GENERAL NUTRITION COMPANIES, INC.

                                      By: /s/ Dave Heilman
                                         -------------------------
                                         Name: Dave Heilman
                                         Title: Vice President

                                         Address:
                                         300 6th Avenue
                                         Pittsburgh, PA 17011

                                      VULCAN VENTURES INCORPORATED,

                                      By:  /s/ William D. Savoy
                                         -------------------------
                                         Name: William D. Savoy
                                         Title: President

                                         Address:
                                         110 110th Avenue NE, Suite 550
                                         Bellevue, WA 98004
<PAGE>

                                       4

                                         KLEINER PERKINS CAUFIELD & BYERS VIII,
                                         L.P.,

                                         By: KPCB VIII Associates, L.P., its
                                             General Partner

                                         By:   /s/ Brook H. Byers
                                            -------------------------
                                            Name: Brook H. Byers
                                            a General Partner

                                            Address:
                                            2750 Sand Hill Road
                                            Menlo Park, CA 94025

                                         KPCB VIII FOUNDERS FUND, L.P.,

                                         By: KPCB VIII Associates, L.P., its
                                             General Partner

                                         By:   /s/ Brook H. Byers
                                            -------------------------
                                            Name: Brook H. Byers
                                            a General Partner

                                            Address:
                                            2750 Sand Hill Road
                                            Menlo Park, CA 94025

                                        KPCB LIFE SCIENCES ZAIBATSU FUND II,
                                        L.P.

                                        By: KPCB VII Associates, L.P., its
                                            General Partner

                                         By:    /s/ Brook H. Byers
                                            -------------------------
                                            Name: Brook H. Byers
                                            a General Partner

                                            Address:
                                            2750 Sand Hill Road
                                            Menlo Park, CA 94025
<PAGE>

                                       5

                                         AMAZON.COM, INC.

                                         By: /s/ Russell Grandinetti
                                            -------------------------
                                            Name: Russell Grandinetti
                                            Title: Treasurer

                                            Address:
                                            1516 2nd Avenue
                                            Seattle, WA 98101

                                         PETER M. NEUPERT

                                             /s/ Peter M. Neupert
                                         ----------------------------
                                            Peter M. Neupert

                                            Address:
                                            13920 SE Eastgate Way, Suite 300
                                            Bellevue, WA 98005

                                         DRUGSTORE.COM FOUNDATION

                                         By:  /s/ Peter M. Neupert
                                            -------------------------
                                            Name: Peter M. Neupert
                                            Title: President

                                            Address:
                                            13920 SE Eastgate Way, Suite 300
                                            Bellevue, WA 98005

                                         MAVERON EQUITY PARTNERS, L.P.

                                         By: /s/ Dan Levitan
                                            -------------------------
                                            Name: Dan Levitan
                                            Title: Manager, MAVERON
                                            GENERAL PARTNER LLC

                                            Address:
                                            800 Fifth Ave., Suite 4100
                                            Seattle, WA 98104
<PAGE>

                                       6

                                         LIBERTY DS, INC.

                                         By:   /s/ Mark D. Rozells
                                            -------------------------
                                            Name: Mark D. Rozells
                                            Title: EVP: CFO

                                            Address:
                                            9197 South Peoria Street
                                            Englewood, CO  80112

<PAGE>

                                       7

                                   EXHIBIT A

                                   INVESTORS

Name and Address
----------------

Rite Aid Corporation
30 Hunter Lane
Camp Hill, PA 17011

General Nutrition Companies, Inc.
300 6th Avenue
Pittsburgh, PA 15222

Vulcan Ventures Incorporated
110th Avenue Northeast, Suite 550
Bellevue, WA  98004

Kleiner Perkins Caufield & Byers VIII
2750 Sand Hill Road
Menlo Park, CA 94025

KPCB VIII Founders Fund, L.P.
2750 Sand Hill Road
Menlo Park, CA 94025

KPCB Life Sciences Zaibatsu Fund II, L.P.
2750 Sand Hill Road
Menlo Park, CA 94025

Amazon.com, Inc.
1516 2nd Avenue
Seattle, WA 98101
Attn: General Counsel

Peter M. Neupert
13920 SE Eastgate Way, Suite 300
Bellevue, WA  98005

Maveron Equity Partners, L.P.
800 Fifth Avenue, Suite 4100
Seattle, WA  98104
<PAGE>

                                       8

Liberty DS, Inc.
9197 South Peoria Street
Englewood, CO  80112

drugstore.com Foundation
Attn:  Alesia L. Pinney
13920 SE Eastgate Way, Ste. 300
Bellevue, WA  98005

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