Exhibit 99.1

Questcor Reports Third Quarter Financial Results

ANAHEIM, Calif., October 23, 2012 — Questcor Pharmaceuticals, Inc. (NASDAQ: QCOR) today reported financial results for the third quarter and nine months ended September 30, 2012.

Net sales for the third quarter were $140.3 million, reflecting expanded physician usage of H.P. Acthar^® Gel (repository corticotropin injection) in the treatment of serious, difficult-to-treat autoimmune and inflammatory disorders. Net sales in the third quarter of 2011 were $59.8 million.

GAAP earnings for the third quarter were $0.91 per diluted share, compared to $0.35 per diluted common share for last year’s comparable quarter. Non-GAAP earnings for the quarter ended September 30, 2012 were $0.97 per diluted common share. Non-GAAP earnings exclude non-cash share-based compensation expense, impairment of purchased technology and goodwill, and depreciation and amortization expense. Non-GAAP earnings for the year ago quarter were $0.37 per diluted common share.

Questcor shipped 5,590 vials of Acthar during the third quarter 2012, up 92 percent compared to 2,910 vials in the year ago quarter. Quarterly vial shipments are subject to significant variation due to the size and timing of individual orders received from Questcor’s distributor. The timing of when these orders are received and filled can significantly affect net sales and net income in any particular quarter. Channel inventory at the end of the third quarter appeared to be within the normal historical range. Questcor believes that investors should consider the Company’s results over several quarters when analyzing its performance.

“Overall, our commercial expansion effort continued to show progress during the third quarter,” said Don M. Bailey, President and CEO of Questcor. “Health care providers are expanding their usage of Acthar as an FDA-approved treatment alternative for patients with idiopathic types of nephrotic syndrome, MS relapses and rheumatology related conditions. We also continue to support patients suffering from infantile spasms.”

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“Based on information available as of this release, patients with serious, difficult-to-treat medical conditions addressed by Acthar on-label indications have continued to have access to Acthar through commercial insurance, Medicare, Medicaid and other government programs, as well as through our free drug program for uninsured patients,” noted Steve Cartt, Chief Operating Officer of Questcor. “Acthar is most commonly prescribed by physicians as an appropriate treatment alternative for patients in whom first-line therapies have not provided the intended treatment outcome and an additional FDA-approved treatment alternative is needed. For such patients, insurance coverage for Acthar continued to remain favorable.”

Year-to-Date Financial Results

Net sales for the first nine months of 2012 were $348.8 million, compared to $142.6 million in the first nine months of 2011. GAAP earnings for the first nine months of 2012 were $2.12 per diluted common share, compared with $0.73 per diluted common share for the comparable period of 2011. Non-GAAP earnings for the nine months ended September 30, 2012 were $2.25 per diluted common share, excluding non-cash share-based compensation expense and depreciation and amortization expense. Non-GAAP earnings for the comparable period of 2011 were $0.80 per diluted common share.

Shipped Acthar Vial and Prescription Trend Information

The Company has been publicly disclosing on Form 8-K shipped vial and prescription trend information on a monthly basis for the past several months. Sales have reached a level where the Company believes that the more traditional approach of providing financial information and related analysis of results on a quarterly basis is appropriate, and the Company expects to return to a quarterly public filing approach going forward.

Because Acthar prescriptions are filled at specialty pharmacies, the Company does not receive complete information regarding either the number of prescriptions or the number of vials by therapeutic area for all of the patients being treated with Acthar. However, Questcor monitors trends in payer mix and areas of therapeutic use for new Acthar prescriptions based on data from its reimbursement support center. Questcor estimates that over 90 percent of new Acthar prescriptions are processed by this support center, but believes that very few refill prescriptions are processed there.

In an effort to help investors better understand historical trends in Acthar prescriptions within each of its current three key therapeutic areas, Questcor is providing quarterly prescription information for the time period January 1, 2010 through September 30, 2012. Prescriptions processed by the Company’s reimbursement center are segmented into one of two groups — “Paid” and “Fully Rebated.”

“Paid” prescriptions (Rxs) include all prescriptions in the following payer categories:

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“Fully Rebated” prescriptions (Rxs) include:

The following tables show, for each of the three key Acthar therapeutic uses, the number of new prescriptions shipped grouped into “Paid” and “Fully Rebated”:

Nephrotic Syndrome (and related conditions) New Rxs

Multiple Sclerosis (and related conditions) New Rxs

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Infantile Spasms (and related conditions) New Rxs*

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Rheumatology (and related conditions) New Rxs*

Notes:

(1) Because the March 2010 health care legislation made Medicaid Managed Care Organization (MCO) prescriptions rebate eligible effective March 23, 2010, a rebate liability for the MCO prescriptions estimated to be filled on or after March 23, 2010 has been accrued. The Company does not have the ability to accurately identify every Medicaid Managed Care prescription so it is possible that some prescriptions identified as “Paid” in the tables may subsequently be reclassified as “Fully Rebated.”

(2) “Related Conditions” includes diagnoses that are either alternate descriptions of the medical condition or are closely related to the medical condition, which is the focus of the table. For example, a prescription for “demyelinating disease of the central nervous system” would be included as an MS-related condition for purpose of this table. About 5% of the prescriptions in the tables are for related conditions.

(3) A prescription may or may not represent a new patient or a new therapy for the patient receiving the prescription. Questcor uses business rules to determine whether a prescription should be included in this table. From time to time the Company may modify these rules, which could cause some changes to the historic numbers in the tables above.

(4) Historical trend information is not necessarily indicative of future results. Additionally, paid prescriptions should not be viewed as predictive of Questcor’s net sales due to a variety of factors, including changes in the number of vials used in connection with each prescription.

Acthar Label Information

The product label for Acthar includes 19 FDA-approved indications. Substantially all of the Company’s net sales currently result from Acthar prescriptions for the following on-label indications of:

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Share Repurchase Program and Cash Dividend

The Company used $58.1 million in cash to repurchase 1,484,300 shares of its common stock in open market transactions, at an average price of $39.15 per share, during the third quarter of 2012. On September 28, 2012, the Company announced that its Board of Directors increased the Company’s common stock repurchase program authorization to 7 million shares. This authorization includes the 3.2 million shares that were remaining under the prior authorization. Shares outstanding were 58.5 million at September 30, 2012 and 62.7 million at September 30, 2011.

On September 28, 2012, the Company announced that its Board of Directors adopted a policy to pay a regular quarterly dividend in such amounts as the Board of Directors may determine from time to time. The Company’s Board of Directors declared an initial quarterly cash dividend of $0.20 per share to all shareholders of record at the close of business on October 31, 2012, payable on November 15, 2012. The Company has been notified that NASDAQ has established an “ex-dividend” date for the Company’s shares of common stock of October 29, 2012, meaning that investors who purchase shares of our common stock on or after October 29, 2012 would not be entitled to the dividend for which the record date is October 31, 2012.

Non-GAAP Financial Measures

The Company believes it is important to share non-GAAP financial metrics with shareholders as these metrics may better represent the ongoing economics of the business and reflect how we manage the business. Accordingly, management believes investors’ understanding of the Company’s financial performance is enhanced as a result of the disclosure of these non-GAAP financial metrics. Non-GAAP net income should not be viewed in isolation, or as a substitute for, or as superior to, reported GAAP net income. The reconciliation between GAAP and Non-GAAP net income is provided with the financial tables included with this release.

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Conference Call and Webcast and Investor Communications

The Company will host a conference call and slide presentation via webcast today, October 23, 2012, at 4:30 p.m. ET/ 1:30 p.m. PT. The call can be accessed three ways:

About Questcor

Questcor Pharmaceuticals, Inc. is a biopharmaceutical company focused on the treatment of patients with serious, difficult-to-treat autoimmune and inflammatory disorders. Questcor’s primary product is H.P. Acthar^® Gel (repository corticotropin injection), an injectable drug that is approved by the FDA for the treatment of 19 indications. Of these 19 indications, Questcor currently generates substantially all of its net sales from the following indications: the treatment of proteinuria in idiopathic types of nephrotic syndrome, the treatment of acute exacerbations of multiple sclerosis in adults, the treatment of infantile spasms in children under two years of age, and the treatment of certain rheumatology-related conditions. Questcor is also exploring the possibility of developing markets for other on-label indications and the possibility of pursuing FDA approval of additional indications not currently on the Acthar label where there is high unmet medical need. For more information about Questcor, please visit www.questcor.com.

Note: Except for the historical information contained herein, this press release contains forward-looking statements that have been made pursuant to the Private Securities Litigation Reform Act of 1995. These statements relate to future events or our future financial performance. In some cases, you can identify forward-looking statements by terminology such as “believes,” “continue,” “could,” “estimates,” “expects,” “growth,” “may,” “plans,” “potential,” “remain,” “should,” “substantial” or “will” or the negative of such terms and other comparable terminology. These statements are only predictions. Actual events or results may differ materially. Factors that could cause or contribute to such differences include, but are not limited to, the following:

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The risk factors and other information contained in these documents should be considered in evaluating Questcor’s prospects and future financial performance.

Questcor undertakes no obligation to publicly release the result of any revisions to these forward-looking statements, which may be made to reflect events or circumstances after the date of this release.

For more information, please visit www.questcor.com or www.acthar.com.

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CONTACT INFORMATION:

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QUESTCOR PHARMACEUTICALS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME

(In thousands, except per share data)

(unaudited)

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Net income per share – basic and diluted may not foot due to rounding.

Use of Non-GAAP Financial Measures

Our “non-GAAP adjusted net income” excludes the following items from GAAP net income:

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Questcor Pharmaceuticals, Inc.

CONDENSED CONSOLIDATED BALANCE SHEETS

(In thousands, except share amounts)

(unaudited)

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Questcor Pharmaceuticals, Inc.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands)

(unaudited)

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