<PAGE>   1
           AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 16, 1999
                                         REGISTRATION STATEMENT NO. 333-
--------------------------------------------------------------------------------


                UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933


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

                             AVANIR PHARMACEUTICALS
             (Exact name of registrant as specified in its charter)

            CALIFORNIA                                    33-0314804
  (State or other jurisdiction              (I.R.S. Employer Identification No.)
of incorporation or organization)

                       9393 Towne Centre Drive, Suite 200
                           San Diego, California 92121
               (Address of Principal Executive Offices, Zip Code)

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

                             1998 STOCK OPTION PLAN
                                       AND
              OPTIONS GRANTED TO NEW DIRECTORS OUTSIDE OF THE PLAN
                            (Full title of the plan)

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

                             DR. GERALD J. YAKATAN,
                       9393 TOWNE CENTRE DRIVE, SUITE 200
                           SAN DIEGO, CALIFORNIA 92121
                                 (619) 558-0364
(Name, address, and telephone number, including area code, of agent for service)

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

                                   Copies to:
                             JOHN J. HENTRICH, ESQ.
                                BAKER & MCKENZIE
                        101 WEST BROADWAY, TWELFTH FLOOR
                           SAN DIEGO, CALIFORNIA 92101
                                 (619) 236-1441

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

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------
                                                               PROPOSED
                                                                MAXIMUM        PROPOSED MAXIMUM       AMOUNT OF
TITLE OF SECURITIES TO                       AMOUNT TO BE    OFFERING PRICE        AGGREGATE        REGISTRATION
     BE REGISTERED                          REGISTERED(1)      PER SHARE        OFFERING PRICE           FEE
----------------------------------------------------------------------------------------------------------------
<S>                                         <C>              <C>               <C>                  <C>
Class A Common Stock,
    no par value per share..............     1,875,000(2)     $0.82813(4)       $1,552,734(4)        $431.66
----------------------------------------------------------------------------------------------------------------
Class A Common Stock,
    no par value per share..............       125,000(3)        $1.50(5)         $187,500(5)         $52.13
----------------------------------------------------------------------------------------------------------------
</TABLE>

(1) This Registration Statement also shall cover any additional shares of Class
    A Common Stock that become issuable by reason of any stock dividend, stock
    split, recapitalization or other similar transaction effected without the
    receipt of consideration that results in an increase in the number of the
    Registrant's outstanding shares of Class A Common Stock.

(2) Consists of 1,875,000 shares of Class A Common Stock issuable under the 1998
    Stock Option Plan.

(3) Consists of shares of Class A Common Stock issuable upon the exercise of
    options granted outside of the plan.

(4) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h)(1) and (c) of the Securities Act of 1933. Pursuant
    to Rule 457(c), the maximum offering price per share is $0.82813, the
    average of the high and low prices of a
<PAGE>   2
    share of the Registrant's Class A Common Stock as reported on the Nasdaq
    National Market System on July 14, 1999, and the maximum aggregate offering
    price of $1,552,734 is the product of $0.82813 and the number of shares of
    the Registrant's Class A Common Stock being registered hereby.

(5) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h)(1) of the Securities Act of 1933. Pursuant to Rule
    457(h)(1), the maximum offering price per share is $1.50, the actual
    exercise price for the shares of Class A Common Stock subject to outstanding
    stock options previously granted to the Registrant's directors outside of
    any plan, and the maximum aggregate offering price of $187,500 is the
    product of $1.50 and the number of shares of the Registrant's Class A Common
    Stock subject to outstanding stock options previously granted to the
    Registrant's directors outside of any plan that are being registered hereby.


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


                                      -2-
<PAGE>   3
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

        We incorporate by reference in this prospectus and encourage you to read
the following documents that we have filed with the SEC pursuant to the
requirements of the Securities Exchange Act of 1934:

        1.      Our Amended Annual Report on Form 10-K/A for the fiscal year
                ended September 30, 1998 filed with the SEC on February 2, 1999;

        2.      Our Definitive Proxy Statement filed with the SEC on January 4,
                1999;

        3.      Our Quarterly Report on Form 10-Q for the quarter ended December
                31, 1998 filed with the SEC on February 16, 1999;

        4.      Our Current Reports on Form 8-K filed with the SEC on January
                25, 1999, March 11, 1999, April 1, 1999 and April 20, 1999;

        5.      Our Definitive Special Proxy Statement filed with the SEC on
                April 13, 1999;

        6.      Our Quarterly Report on Form 10-Q for the quarter ended March
                31, 1999 filed with the SEC on May 17, 1999; and

        7.      The description of our Class A Common Stock contained in our
                Registration Statement on Form 8-A filed with the SEC on July
                31, 1990, including any amendments or reports filed for the
                purpose of updating the description.

        We also incorporate by reference as part of this prospectus and
encourage you to read all reports and other documents that we have filed (or
will file) with the SEC under the Securities Exchange Act of 1934, that are
after the date of this prospectus and before the termination of the offering of
the shares registered under this prospectus. You should understand that, if any
statement contained in a report or document that is incorporated by reference in
this prospectus is modified or superseded, then the later filed report or
document will modify or supersede the statements contained in this prospectus.

        We will provide without charge to each person, including any beneficial
owner, to whom a copy of this prospectus is delivered, upon the written or oral
request of that person, a copy of any and all documents incorporated by
reference in this prospectus (not including, however, the exhibits to those
documents unless those exhibits are specifically incorporated by reference in
such documents). Requests should be sent to the attention of the Secretary of
our company, at 9393 Towne Centre Drive, Suite 200, San Diego, California 92121
or you may call and ask for the Secretary of our company at (619) 558-0364.

ITEM 4. DESCRIPTION OF SECURITIES.

Not applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

Not applicable.

                                      II-3
<PAGE>   4
ITEM 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        We hereby incorporate by reference Sections 204(a)(10) and (11), 204.5
and 317 of the California General Corporation Law which covers the
indemnification of directors, officers, employees and agents of a corporation.
We refer you to Article 6 of our Restated Articles of Incorporation, and Section
3.15 of our Amended and Restated By-Laws, which provide for indemnification by
our company in the manner and to the full extent permitted by California law.

        Beginning August 10, 1992, we have maintained directors' and officers'
liability insurance with policy limits of $7,500,000. The policy covers 100
percent of losses arising from, among other things, claims of breach of duty,
neglect, error, alleged misstatement, misleading statement or omission by the
directors and officers in their capacity as such. Payment for loss would be made
to or on our behalf where we are required or permitted to indemnify directors or
officers for covered losses pursuant to statutory or common law, our Restated
Articles of Incorporation or Amended and Restated By-Laws or by agreement. The
policy provides for retention of $5,000 per director or officer, subject to a
maximum of $10,000 for each loss, except in the case of payment for loss to or
on our behalf, in which case the retention is $100,000.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

Not applicable.

ITEM 8. EXHIBITS.


<TABLE>
<CAPTION>
(a)         Exhibits
---------   -----------------------------------------------------------------------------------------------------
<S>         <C>
4.1         --    Forms of Class A and Class B Common Stock Certificates (1)

4.2         --    Class D Warrant Agreement (including form of Class D Warrant Certificate) (2)

4.3         --    Convertible Note, dated February 26, 1997, issued to RGC International Investors, LDC (3)

4.4         --    Form of Class G Stock Purchase Warrant (3)

4.5         --    Rights Agreement, dated as of March 5, 1999, between AVANIR Pharmaceuticals and American
                  Stock Transfer & Trust Company (4)

4.6         --    Form of Rights Certificate with respect to the Rights Agreement dated as of March 5, 1999 (4)

4.7         --    Form of Series D Convertible Preferred Stock Certificate (5)

4.8         --    Amended and Restated Class I Stock Purchase Warrant dated March 4, 1999 (6)

4.9         --    Form of Class J Stock Purchase Warrant (5)

4.10        --    Class K Stock Purchase Warrant dated April 1, 1999 (6)

4.11        --    Class L Stock Purchase Warrant, dated June 8, 1999 (9)

5.1         --    Opinion of Baker & McKenzie

23.1        --    Independent Auditors' Consent

23.2        --    Consent of Baker & McKenzie (included in Exhibit 5.1)

24          --    Power of Attorney (reference is made to page II-5 of this registration statement.)

99.1        --    1994 Stock Option Plan (7)

99.2        --    1998 Stock Option Plan (8)
</TABLE>

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

1.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-32742, declared effective by the SEC on May 8, 1990.


                                      II-4
<PAGE>   5
2.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-49082, declared effective by the SEC on October 26, 1992.

3.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed March 10, 1997.

4.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on March 11,
        1999.

5.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 1, 1999.

6.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 20,
        1999.

7.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Annual Report on Form 10-K for the fiscal year
        ended September 30, 1994, filed December 29, 1994.

8.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed May 17, 1999.

9.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Amendment No. 1 to the Registration Statement on
        Form S-3, filed July 15, 1999.


        (b)     All other schedules are omitted for the reason that the
information is included in the financial statements or the related notes or that
they are not required or are not applicable.


ITEM 9. UNDERTAKINGS.

        We hereby undertake:

        1.      To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

                i.      To include any prospectus required by Section 10(a)(3)
of the Securities Act of 1933;

                ii.     To reflect in the prospectus any facts or events arising
after the effective date of this registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this registration
statement; and

                iii.    To include any material information with respect to the
plan of distribution not previously disclosed in this registration statement or
any material change to such information in this registration statement;
provided, however, that paragraphs 1(i) and 1(ii) will not apply if we file with
or furnish to the SEC the information that is required to be included in a
post-effective amendment by those paragraphs in periodic reports pursuant to
section 13 or section 15(d) of the Securities Exchange Act of 1934 that are
incorporated by reference in this registration statement.

        2.      That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment will be deemed to be
a new registration statement relating to the securities registered therein, and
the offering of such securities at that time will be deemed to be the initial
bona fide offering thereof.


                                      II-5
<PAGE>   6
        3.      To remove from registration by means of a post-effective
amendment any of the securities being registered that remain unsold upon the
termination of our 1998 Stock Option Plan.

        We also undertake that, for purposes of determining any liability under
the Securities Act of 1933, each filing of our annual report pursuant to Section
13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to Section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference
in this registration statement will be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time will be deemed to be the initial bona fide offering thereof.

        Insofar as indemnification for liabilities arising under the Securities
Act of 1933, may be permitted to directors, officers and controlling persons of
the registrant pursuant to the provisions of its Restated Articles of
Incorporation and Amended and Restated By-Laws of the registrant, the California
General Corporation Law or otherwise, the registrant has been advised that in
the opinion of the SEC such indemnification is against public policy as
expressed in the Securities Act of 1933, and is therefore unenforceable. If a
claim for indemnification against such liabilities (other than the payment by
the issuer of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, then the registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act of 1933, and will be governed by the final adjudication of such
issue.

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
the requirements for filing on Form S-8 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Diego, State of California, on this 16th day of
July, 1999.

                                  AVANIR PHARMACEUTICALS



                                  By: /s/ Gerald J. Yakatan, Ph.D.
                                      ------------------------------------------
                                      Gerald J. Yakatan, Ph.D.
                                      President and Chief Executive Officer

                                      POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below hereby constitutes and appoints Gerald J. Yakatan, Ph.D. and
Gregory P. Hanson, and each of them acting individually, as his
attorney-in-fact, each with full power of substitution and resubstititution, for
him in any and all capacities, to sign any and all amendments to this
registration statement on Form S-8, and to file the same, with all exhibits
thereto, and other documents in connection therewith, with the Securities and
Exchange Commission, granting unto said attorneys-in-fact and agents, each
acting alone, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully for
all intents and purposes as he might or could do in person, hereby ratifying and
confirming our signatures as they may be signed by our said attorneys-in-fact to
any and all amendments to this registration statement.


                                      II-6
<PAGE>   7
        Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.


<TABLE>
<CAPTION>
         Signature                            Title
         ---------                            -----
<S>                                           <C>


/s/Gerald J. Yakatan, Ph.D.                   President, Chief Executive Officer and a Director
---------------------------------------       (Principal Executive Officer)
        Gerald J. Yakatan, Ph.D.




/s/Gregory P. Hanson                          Vice President, Finance and Chief Financial
---------------------------------------       Officer (Principal Financial and Accounting
        Gregory P. Hanson                     Officer)




George P. Rutland                             Chairman of the Board of Directors
---------------------------------------
        George P. Rutland




Dennis J. Carlo, Ph.D.                        Director
---------------------------------------
        Dennis J. Carlo, Ph.D.




Michael W. George                             Director
---------------------------------------
        Michael W. George



                                              Director
---------------------------------------
        Edward L. Hennessy, Jr.




/s/James B. Glavin                            Director
---------------------------------------
        James B. Glavin




/s/Kenneth E. Olson                           Director
---------------------------------------
        Kenneth E. Olson
</TABLE>


                                      II-7
<PAGE>   8
<TABLE>
<CAPTION>
         Signature                            Title
         ---------                            -----
<S>                                           <C>


/s/Stuart A. Samuels                          Director
---------------------------------------
        Stuart A. Samuels




/s/Joseph E. Smith                            Director
---------------------------------------
        Joseph E. Smith
</TABLE>


                                      II-8
<PAGE>   9
                                INDEX TO EXHIBITS

<TABLE>
<CAPTION>
   EXHIBIT
   NUMBER          DESCRIPTION
------------       --------------------------------------------------------------------------------
<S>                <C>

4.1                Forms of Class A and Class B Common Stock Certificates (1)

4.2                Class D Warrant Agreement (including form of Class D Warrant Certificate) (2)

4.3                Convertible Note, dated February 26, 1997, issued to RGC International
                   Investors, LDC (3)

4.4                Form of Class G Stock Purchase Warrant (3)

4.5                Rights Agreement, dated as of March 5, 1999, between AVANIR
                   Pharmaceuticals and American Stock Transfer & Trust Company
                   (4)

4.6                Form of Rights Certificate with respect to the Rights Agreement dated as of
                   March 5, 1999 (4)

4.7                Form of Series D Convertible Preferred Stock Certificate (5)

4.8                Amended and Restated Class I Stock Purchase Warrant dated March 4, 1999 (6)

4.9                Form of Class J Stock Purchase Warrant (5)

4.10               Class K Stock Purchase Warrant dated April 1, 1999 (6)

4.11               Class L Stock Purchase Warrant, dated June 8, 1999 (9)

5.1                Opinion of Baker & McKenzie

23.1               Independent Auditors' Consent

23.2               Consent of Baker & McKenzie (included in Exhibit 5.1)

24                 Power of Attorney (reference is made to page II-5 of this registration
                   statement.)

99.1               1994 Stock Option Plan (7)

99.2               1998 Stock Option Plan (8)
</TABLE>

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

1.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-32742, declared effective by the SEC on May 8, 1990.

2.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-49082, declared effective by the SEC on October 26, 1992.

3.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed March 10, 1997.

4.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on March 11,
        1999.


                                      II-9
<PAGE>   10
5.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 1, 1999.

6.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 20,
        1999.

7.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Annual Report on Form 10-K for the fiscal year
        ended September 30, 1994, filed December 29, 1994.

8.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed May 17, 1999.

9.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Amendment No. 1 to the Registration Statement on
        Form S-3, filed July 15, 1999.


                                     II-10
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 24678}]
{"company-data": {"conformed-name": "AVANIR PHARMACEUTICALS", "cik": "0000858803", "assigned-sic": "2834", "irs-number": "330314804", "state-of-incorporation": "CA", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-83089", "film-number": "99666014"}, "business-address": {"street1": "9393 TOWNE CENTRE DRIVE", "street2": "SUITE 200", "city": "SAN DIEGO", "state": "CA", "zip": "93121-3016", "phone": "6195580364"}, "mail-address": {"street1": "9393 TOWN CENTRE DRIVE", "street2": "SUITE 200", "city": "SAN DIEGO", "state": "CA", "zip": "93121-3016"}, "former-company": {"former-conformed-name": "LIDAK PHARMACEUTICALS", "date-changed": "19920703"}}
1
           AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 16, 1999
                                         REGISTRATION STATEMENT NO. 333-
--------------------------------------------------------------------------------

                UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                             AVANIR PHARMACEUTICALS
             (Exact name of registrant as specified in its charter)

            CALIFORNIA                                    33-0314804
  (State or other jurisdiction              (I.R.S. Employer Identification No.)
of incorporation or organization)

                       9393 Towne Centre Drive, Suite 200
                           San Diego, California 92121
               (Address of Principal Executive Offices, Zip Code)

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

                             1998 STOCK OPTION PLAN
                                       AND
              OPTIONS GRANTED TO NEW DIRECTORS OUTSIDE OF THE PLAN
                            (Full title of the plan)

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

                             DR. GERALD J. YAKATAN,
                       9393 TOWNE CENTRE DRIVE, SUITE 200
                           SAN DIEGO, CALIFORNIA 92121
                                 (619) 558-0364
(Name, address, and telephone number, including area code, of agent for service)

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

                                   Copies to:
                             JOHN J. HENTRICH, ESQ.
                                BAKER & MCKENZIE
                        101 WEST BROADWAY, TWELFTH FLOOR
                           SAN DIEGO, CALIFORNIA 92101
                                 (619) 236-1441

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

                         CALCULATION OF REGISTRATION FEE
----------------------------------------------------------------------------------------------------------------
                                                               PROPOSED
                                                                MAXIMUM        PROPOSED MAXIMUM       AMOUNT OF
TITLE OF SECURITIES TO                       AMOUNT TO BE    OFFERING PRICE        AGGREGATE        REGISTRATION
     BE REGISTERED                          REGISTERED(1)      PER SHARE        OFFERING PRICE           FEE
----------------------------------------------------------------------------------------------------------------
Class A Common Stock,
    no par value per share..............     1,875,000(2)     $0.82813(4)       $1,552,734(4)        $431.66
----------------------------------------------------------------------------------------------------------------
Class A Common Stock,
    no par value per share..............       125,000(3)        $1.50(5)         $187,500(5)         $52.13
----------------------------------------------------------------------------------------------------------------
(1) This Registration Statement also shall cover any additional shares of Class
    A Common Stock that become issuable by reason of any stock dividend, stock
    split, recapitalization or other similar transaction effected without the
    receipt of consideration that results in an increase in the number of the
    Registrant's outstanding shares of Class A Common Stock.

(2) Consists of 1,875,000 shares of Class A Common Stock issuable under the 1998
    Stock Option Plan.

(3) Consists of shares of Class A Common Stock issuable upon the exercise of
    options granted outside of the plan.

(4) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h)(1) and (c) of the Securities Act of 1933. Pursuant
    to Rule 457(c), the maximum offering price per share is $0.82813, the
    average of the high and low prices of a
2
    share of the Registrant's Class A Common Stock as reported on the Nasdaq
    National Market System on July 14, 1999, and the maximum aggregate offering
    price of $1,552,734 is the product of $0.82813 and the number of shares of
    the Registrant's Class A Common Stock being registered hereby.

(5) Estimated solely for the purpose of calculating the registration fee
    pursuant to Rule 457(h)(1) of the Securities Act of 1933. Pursuant to Rule
    457(h)(1), the maximum offering price per share is $1.50, the actual
    exercise price for the shares of Class A Common Stock subject to outstanding
    stock options previously granted to the Registrant's directors outside of
    any plan, and the maximum aggregate offering price of $187,500 is the
    product of $1.50 and the number of shares of the Registrant's Class A Common
    Stock subject to outstanding stock options previously granted to the
    Registrant's directors outside of any plan that are being registered hereby.

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

                                      -2-
3
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

        We incorporate by reference in this prospectus and encourage you to read
the following documents that we have filed with the SEC pursuant to the
requirements of the Securities Exchange Act of 1934:

        1.      Our Amended Annual Report on Form 10-K/A for the fiscal year
                ended September 30, 1998 filed with the SEC on February 2, 1999;

        2.      Our Definitive Proxy Statement filed with the SEC on January 4,
                1999;

        3.      Our Quarterly Report on Form 10-Q for the quarter ended December
                31, 1998 filed with the SEC on February 16, 1999;

        4.      Our Current Reports on Form 8-K filed with the SEC on January
                25, 1999, March 11, 1999, April 1, 1999 and April 20, 1999;

        5.      Our Definitive Special Proxy Statement filed with the SEC on
                April 13, 1999;

        6.      Our Quarterly Report on Form 10-Q for the quarter ended March
                31, 1999 filed with the SEC on May 17, 1999; and

        7.      The description of our Class A Common Stock contained in our
                Registration Statement on Form 8-A filed with the SEC on July
                31, 1990, including any amendments or reports filed for the
                purpose of updating the description.

        We also incorporate by reference as part of this prospectus and
encourage you to read all reports and other documents that we have filed (or
will file) with the SEC under the Securities Exchange Act of 1934, that are
after the date of this prospectus and before the termination of the offering of
the shares registered under this prospectus. You should understand that, if any
statement contained in a report or document that is incorporated by reference in
this prospectus is modified or superseded, then the later filed report or
document will modify or supersede the statements contained in this prospectus.

        We will provide without charge to each person, including any beneficial
owner, to whom a copy of this prospectus is delivered, upon the written or oral
request of that person, a copy of any and all documents incorporated by
reference in this prospectus (not including, however, the exhibits to those
documents unless those exhibits are specifically incorporated by reference in
such documents). Requests should be sent to the attention of the Secretary of
our company, at 9393 Towne Centre Drive, Suite 200, San Diego, California 92121
or you may call and ask for the Secretary of our company at (619) 558-0364.

ITEM 4. DESCRIPTION OF SECURITIES.

Not applicable.

ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

Not applicable.

                                      II-3
4
ITEM 6.   INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        We hereby incorporate by reference Sections 204(a)(10) and (11), 204.5
and 317 of the California General Corporation Law which covers the
indemnification of directors, officers, employees and agents of a corporation.
We refer you to Article 6 of our Restated Articles of Incorporation, and Section
3.15 of our Amended and Restated By-Laws, which provide for indemnification by
our company in the manner and to the full extent permitted by California law.

        Beginning August 10, 1992, we have maintained directors' and officers'
liability insurance with policy limits of $7,500,000. The policy covers 100
percent of losses arising from, among other things, claims of breach of duty,
neglect, error, alleged misstatement, misleading statement or omission by the
directors and officers in their capacity as such. Payment for loss would be made
to or on our behalf where we are required or permitted to indemnify directors or
officers for covered losses pursuant to statutory or common law, our Restated
Articles of Incorporation or Amended and Restated By-Laws or by agreement. The
policy provides for retention of $5,000 per director or officer, subject to a
maximum of $10,000 for each loss, except in the case of payment for loss to or
on our behalf, in which case the retention is $100,000.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

Not applicable.

ITEM 8. EXHIBITS.
(a)         Exhibits
---------   -----------------------------------------------------------------------------------------------------
4.1         --    Forms of Class A and Class B Common Stock Certificates (1)

4.2         --    Class D Warrant Agreement (including form of Class D Warrant Certificate) (2)

4.3         --    Convertible Note, dated February 26, 1997, issued to RGC International Investors, LDC (3)

4.4         --    Form of Class G Stock Purchase Warrant (3)

4.5         --    Rights Agreement, dated as of March 5, 1999, between AVANIR Pharmaceuticals and American
                  Stock Transfer & Trust Company (4)

4.6         --    Form of Rights Certificate with respect to the Rights Agreement dated as of March 5, 1999 (4)

4.7         --    Form of Series D Convertible Preferred Stock Certificate (5)

4.8         --    Amended and Restated Class I Stock Purchase Warrant dated March 4, 1999 (6)

4.9         --    Form of Class J Stock Purchase Warrant (5)

4.10        --    Class K Stock Purchase Warrant dated April 1, 1999 (6)

4.11        --    Class L Stock Purchase Warrant, dated June 8, 1999 (9)

5.1         --    Opinion of Baker & McKenzie

23.1        --    Independent Auditors' Consent

23.2        --    Consent of Baker & McKenzie (included in Exhibit 5.1)

24          --    Power of Attorney (reference is made to page II-5 of this registration statement.)

99.1        --    1994 Stock Option Plan (7)

99.2        --    1998 Stock Option Plan (8)
-----------------------

1.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-32742, declared effective by the SEC on May 8, 1990.

                                      II-4
5
2.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-49082, declared effective by the SEC on October 26, 1992.

3.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed March 10, 1997.

4.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on March 11,
        1999.

5.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 1, 1999.

6.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 20,
        1999.

7.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Annual Report on Form 10-K for the fiscal year
        ended September 30, 1994, filed December 29, 1994.

8.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed May 17, 1999.

9.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Amendment No. 1 to the Registration Statement on
        Form S-3, filed July 15, 1999.

        (b)     All other schedules are omitted for the reason that the
information is included in the financial statements or the related notes or that
they are not required or are not applicable.

ITEM 9. UNDERTAKINGS.

        We hereby undertake:

        1.      To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement:

                i.      To include any prospectus required by Section 10(a)(3)
of the Securities Act of 1933;

                ii.     To reflect in the prospectus any facts or events arising
after the effective date of this registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in this registration
statement; and

                iii.    To include any material information with respect to the
plan of distribution not previously disclosed in this registration statement or
any material change to such information in this registration statement;
provided, however, that paragraphs 1(i) and 1(ii) will not apply if we file with
or furnish to the SEC the information that is required to be included in a
post-effective amendment by those paragraphs in periodic reports pursuant to
section 13 or section 15(d) of the Securities Exchange Act of 1934 that are
incorporated by reference in this registration statement.

        2.      That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment will be deemed to be
a new registration statement relating to the securities registered therein, and
the offering of such securities at that time will be deemed to be the initial
bona fide offering thereof.

                                      II-5
6
        3.      To remove from registration by means of a post-effective
amendment any of the securities being registered that remain unsold upon the
termination of our 1998 Stock Option Plan.

        We also undertake that, for purposes of determining any liability under
the Securities Act of 1933, each filing of our annual report pursuant to Section
13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable,
each filing of an employee benefit plan's annual report pursuant to Section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference
in this registration statement will be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time will be deemed to be the initial bona fide offering thereof.

        Insofar as indemnification for liabilities arising under the Securities
Act of 1933, may be permitted to directors, officers and controlling persons of
the registrant pursuant to the provisions of its Restated Articles of
Incorporation and Amended and Restated By-Laws of the registrant, the California
General Corporation Law or otherwise, the registrant has been advised that in
the opinion of the SEC such indemnification is against public policy as
expressed in the Securities Act of 1933, and is therefore unenforceable. If a
claim for indemnification against such liabilities (other than the payment by
the issuer of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, then the registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act of 1933, and will be governed by the final adjudication of such
issue.

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
the requirements for filing on Form S-8 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Diego, State of California, on this 16th day of
July, 1999.

                                  AVANIR PHARMACEUTICALS

                                  By: /s/ Gerald J. Yakatan, Ph.D.
                                      ------------------------------------------
                                      Gerald J. Yakatan, Ph.D.
                                      President and Chief Executive Officer

                                      POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below hereby constitutes and appoints Gerald J. Yakatan, Ph.D. and
Gregory P. Hanson, and each of them acting individually, as his
attorney-in-fact, each with full power of substitution and resubstititution, for
him in any and all capacities, to sign any and all amendments to this
registration statement on Form S-8, and to file the same, with all exhibits
thereto, and other documents in connection therewith, with the Securities and
Exchange Commission, granting unto said attorneys-in-fact and agents, each
acting alone, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully for
all intents and purposes as he might or could do in person, hereby ratifying and
confirming our signatures as they may be signed by our said attorneys-in-fact to
any and all amendments to this registration statement.

                                      II-6
7
        Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities and on the dates indicated.
Signature                            Title
         ---------                            -----
/s/Gerald J. Yakatan, Ph.D.                   President, Chief Executive Officer and a Director
---------------------------------------       (Principal Executive Officer)
        Gerald J. Yakatan, Ph.D.

/s/Gregory P. Hanson                          Vice President, Finance and Chief Financial
---------------------------------------       Officer (Principal Financial and Accounting
        Gregory P. Hanson                     Officer)

George P. Rutland                             Chairman of the Board of Directors
---------------------------------------
        George P. Rutland

Dennis J. Carlo, Ph.D.                        Director
---------------------------------------
        Dennis J. Carlo, Ph.D.

Michael W. George                             Director
---------------------------------------
        Michael W. George

                                              Director
---------------------------------------
        Edward L. Hennessy, Jr.

/s/James B. Glavin                            Director
---------------------------------------
        James B. Glavin

/s/Kenneth E. Olson                           Director
---------------------------------------
        Kenneth E. Olson
II-7
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Signature                            Title
         ---------                            -----
/s/Stuart A. Samuels                          Director
---------------------------------------
        Stuart A. Samuels

/s/Joseph E. Smith                            Director
---------------------------------------
        Joseph E. Smith
II-8
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                                INDEX TO EXHIBITS
EXHIBIT
   NUMBER          DESCRIPTION
------------       --------------------------------------------------------------------------------
4.1                Forms of Class A and Class B Common Stock Certificates (1)

4.2                Class D Warrant Agreement (including form of Class D Warrant Certificate) (2)

4.3                Convertible Note, dated February 26, 1997, issued to RGC International
                   Investors, LDC (3)

4.4                Form of Class G Stock Purchase Warrant (3)

4.5                Rights Agreement, dated as of March 5, 1999, between AVANIR
                   Pharmaceuticals and American Stock Transfer & Trust Company
                   (4)

4.6                Form of Rights Certificate with respect to the Rights Agreement dated as of
                   March 5, 1999 (4)

4.7                Form of Series D Convertible Preferred Stock Certificate (5)

4.8                Amended and Restated Class I Stock Purchase Warrant dated March 4, 1999 (6)

4.9                Form of Class J Stock Purchase Warrant (5)

4.10               Class K Stock Purchase Warrant dated April 1, 1999 (6)

4.11               Class L Stock Purchase Warrant, dated June 8, 1999 (9)

5.1                Opinion of Baker & McKenzie

23.1               Independent Auditors' Consent

23.2               Consent of Baker & McKenzie (included in Exhibit 5.1)

24                 Power of Attorney (reference is made to page II-5 of this registration
                   statement.)

99.1               1994 Stock Option Plan (7)

99.2               1998 Stock Option Plan (8)
------------------

1.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-32742, declared effective by the SEC on May 8, 1990.

2.      Incorporated by reference to the similarly described exhibit filed in
        connection with the registrant's Registration Statement on Form S-1,
        File No. 33-49082, declared effective by the SEC on October 26, 1992.

3.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed March 10, 1997.

4.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on March 11,
        1999.

                                      II-9
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5.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 1, 1999.

6.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Current Report on Form 8-K filed on April 20,
        1999.

7.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Annual Report on Form 10-K for the fiscal year
        ended September 30, 1994, filed December 29, 1994.

8.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Quarterly Report on Form 10-Q for the quarter
        ended March 31, 1999, filed May 17, 1999.

9.      Incorporated by reference to the similarly described exhibit included
        with the registrant's Amendment No. 1 to the Registration Statement on
        Form S-3, filed July 15, 1999.

                                     II-10