Exhibit 99.1

Questcor Reports Second Quarter Financial Results

-Net Sales and EPS More Than Double from Year Ago Quarter-

-Sales Force Expansions Nearly Complete—Rheumatology Pilot Underway-

-Conference Call and Webcast Today at 4:30 p.m. ET, 1:30 p.m. PT-

ANAHEIM, Calif., July 24, 2012 — Questcor Pharmaceuticals, Inc. (NASDAQ: QCOR) today reported financial results for the second quarter and six months ended June 30, 2012.

Net sales for the second quarter were $112.5 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, most notably idiopathic nephrotic syndrome and MS exacerbations. Net sales in the second quarter 2011 were $46.0 million.

GAAP net income for the second quarter was $41.5 million or $0.65 per diluted common share, compared to $13.9 million, or $0.21 per diluted common share for last year’s comparable quarter. Non-GAAP net income for the quarter ended June 30, 2012 was $44.2 million or $0.69 per diluted common share. Non-GAAP net income excludes non-cash share-based compensation expense and depreciation and amortization expense. Non-GAAP net income for the year ago quarter was $15.2 million, or $0.23 per diluted common share.

The Company used $156.1 million in cash to repurchase 3,730,069 shares of its common stock in open market transactions, at an average price of $41.85 per share, during the second quarter. Shares outstanding were 59.7 million at June 30, 2012 and 62.3 million at June 30, 2011.

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Questcor shipped 4,710 vials of Acthar during the second quarter 2012, up 94% compared to 2,430 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 second quarter appears to be in the normal range. At the end of the first quarter 2012, channel inventory was higher than normal. Questcor believes that investors should consider the Company’s results over several quarters when analyzing its performance.

“In the second quarter, we surpassed $100 million in quarterly net sales for the first time in our history,” said Don M. Bailey, President and CEO of Questcor. “Our strong financial results were driven by increasing usage of Acthar among nephrologists and neurologists. With the expansion of our Nephrology Sales Force now complete, the expansion of our Neurology Sales Force nearing completion, and the initial detailing effort of a small sales force in Rheumatology just getting started, we are optimistic about the potential for Acthar to help an increasing number of patients with serious, difficult-to-treat autoimmune and inflammatory disorders. We also continue to support our free drug program and have provided free drug with a commercial value of over $183 million to patients and hospitals through these programs since September 2007.”

“We completed the expansion of our Nephrology Sales Force to 58 from 28 representatives during the second quarter, with all of the new representatives trained and in the field by early June,” noted Steve Cartt, Chief Operating Officer. “At the same time, we expect the expansion of our Neurology Sales Force to 107 from 77 representatives to be complete in August. In addition, our Rheumatology pilot effort is off to an encouraging start focusing on dermatomyositis (polymyositis). We expect to see the benefit from these three sales forces during the remainder of this year and into 2013.”

Year-to-Date Financial Results

Net sales for the first six months of 2012 were $208.4 million, compared to $82.8 million in the first six months of 2011. GAAP Net income for the first six months of 2012 was $80.0 million, or $1.23 per diluted common share, and compared with $25.1 million, or $0.38 per diluted common share, for the comparable period of 2011. Non-GAAP net income for the six months ended June 30, 2012 was $84.5 million or $1.29 per diluted common share excluding non-cash share-based compensation expense and depreciation and amortization expense. Non-GAAP net income for the comparable period of 2011 was $28.0 million, or $0.43 per diluted common share.

Shipped Acthar Vial and Prescription Trend Information

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,

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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% 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 June 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:

“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

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Multiple Sclerosis (and related conditions) New Rxs

Infantile Spasms (and related conditions) New Rxs*

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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 on-label indications of:

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Acthar is also approved for the following rheumatology-related conditions:

Share Repurchase Program

The Company used $156.1 million in cash to repurchase 3,730,069 shares of its common stock in open market transactions, at an average price of $41.85 per share, during the second quarter. As of June 30, 2012, Questcor had 59.7 million shares of common stock outstanding, with 4.7 million shares remaining under its current common stock repurchase program.

As of July 20, 2012, Questcor’s cash, cash equivalents and short-term investments totaled $129.0 million, and its accounts receivable totaled $53.8 million.

Sales Reserves

Questcor’s sales reserves during the quarter ended June 30, 2012, including the Company’s reserves for Medicaid rebates, represented 14.6% of gross sales of $131.7 million, or $19.2 million of sales reserves. During the year ago quarter, Questcor’s sales reserves, including the Company’s reserves for Medicaid rebates, represented 23.5% of gross sales of $60.1 million. The decrease in the reserve percentage from the year ago was primarily due to an increase in the percentage of total Acthar prescriptions written to treat adults suffering from MS and NS relative to the percentage used to treat infants suffering from IS, as there is a very high percentage of infants enrolled in Medicaid.

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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.

Conference Call and Webcast

The Company will host a conference call and slide presentation via webcast today, July 24, 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 three indications: the treatment of proteinuria in idiopathic types of nephrotic syndrome, the treatment of acute exacerbations of multiple sclerosis in adults, and the treatment of infantile spasms in children under two years of age. With respect to nephrotic syndrome, the FDA has approved Acthar to “induce a diuresis or a remission of proteinuria in the nephrotic syndrome without uremia of the idiopathic type or that due to lupus erythematosus.” Questcor has launched a pilot effort in rheumatology, as Acthar is approved for several rheumatology-related conditions including Dermatomyositis, Polymyositis, Lupus and Rheumatoid Arthritis. Questcor is also exploring the possibility of developing markets for other on-label indications and the

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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,” “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.

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.

Consolidated Balance Sheets

(In thousands, except share amounts)

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Questcor Pharmaceuticals, Inc.

Consolidated Statements of Cash Flows

(In thousands)

(unaudited)

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