Exhibit 99.1

Questcor Reports Record First Quarter Net Sales

-Expanded Sales Force Drives Record 508 Paid Acthar Prescriptions for MS, up

120% from Year Ago Period and up 44% from Fourth Quarter 2010-

-Initial Sales Efforts in Nephrotic Syndrome Deliver Encouraging Results-

-Q1 Net Sales a Record $36.8 Million, up 40% from Prior Year Period-

-Q1 GAAP Net Income Per Diluted Share $0.17-

-Q1 non-GAAP Net Income Per Diluted Share $0.20-

-Conference Call Today at 4:30 p.m. ET-

ANAHEIM, CA – April 26, 2011 — Questcor Pharmaceuticals, Inc. (NASDAQ: QCOR) today reported financial results for its first quarter ended March 31, 2011. Net sales totaled a record $36.8 million for the quarter compared to $26.2 million for the quarter ended March 31, 2010, and $29.3 million for the quarter ended December 31, 2010.

The Company’s financial performance was driven by a 120% year-over-year increase in the number of new paid prescriptions of H.P. Acthar^® Gel (Acthar) for the treatment of multiple sclerosis (MS) exacerbations. In the first quarter, paid Acthar prescriptions for the treatment of nephrotic syndrome (NS) increased to 18 while prescriptions for the treatment of infantile spasms (IS) were 89, which is within the historic range for IS.

“Our strategy to expand the sales force is clearly paying off,” said Don M. Bailey, President and CEO of Questcor. “Paid MS prescriptions are up sharply from last quarter. March was a particularly strong month and this momentum has continued so far in April. We believe that Acthar is filling an increasingly important role in the treatment of exacerbations associated with MS and, looking forward, we expect to continue to grow sales in this important therapeutic area.”

Mr. Bailey added, “We are also encouraged by the early positive results from our small, dedicated nephrology sales team, which initiated selling efforts at the beginning of March. The number of nephrologists who are using Acthar to treat patients with nephrotic syndrome is increasing. In addition, during the second quarter we will initiate a company-sponsored Phase IV trial to study Acthar in the treatment of NS associated with idiopathic membranous nephropathy. Acthar is indicated ‘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’.”

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Non-GAAP and GAAP Net Income

Non-GAAP net income for the quarter ended March 31, 2011 was $12.8 million, or $0.20 per diluted common share. Non-GAAP net income for the quarter ended March 31, 2010 was $8.6 million, or $0.14 per diluted common share.

On a GAAP basis, net income for the first quarter of 2011 was $11.2 million or $0.17 per diluted common share. Net income for the first quarter of 2010 was $7.9 million, or $0.12 per diluted common share.

The Company believes it is important to share these non-GAAP financial measures with shareholders as they 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 our disclosing these non-GAAP financial measures. 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.

Prescription Trend Information for MS, NS and IS

During the first quarter of 2011, Questcor shipped 2,010 vials of Acthar compared to 1,446 vials in the first quarter of 2010. The Company’s quarterly vial shipments continue to be subject to significant variation due to the size and timing of individual orders from our distributor, and the timing of these orders can significantly affect net sales and net income in any particular quarter. For this reason, as well as other factors causing quarter-to-quarter variability in Questcor’s operating results, the Company believes that investors should consider the Company’s results over several quarters when analyzing the Company’s performance.

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 is able to monitor trends in payer mix and areas of therapeutic use for new Acthar prescriptions based on data it receives 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 order to help investors better understand historical trends in sales of Acthar for each of its three key therapeutic uses, acute exacerbations of MS, NS, and IS, Questcor has grouped new prescriptions processed by its reimbursement center into two groups — “Paid” and “Fully Rebated.” “Paid” prescriptions include those prescriptions for which Questcor retains the full selling price for Acthar, as well as Tricare prescriptions that receive a 24% rebate. “Fully Rebated” prescriptions are those for which Questcor can identify that it has recorded a rebate liability approximately equal to or, for periods prior

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to the first quarter of 2010, greater than the price charged to its distributor. From time to time during the past two years, the rebate liability for some government insurance programs has shifted between these two categories. Therefore, the prescriptions that fall into the “Paid” and “Fully Rebated” categories have also shifted over time as follows:

“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”:

Multiple Sclerosis (and related conditions) New Rxs

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Nephrotic Syndrome (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 3/23/10, a rebate liability for the MCO prescriptions estimated to be filled on or after 3/23/10 has been accrued. The Company does not have the ability to accurately identify every MCO 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 alternative 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 new 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 classified as new for inclusion 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.

“Our expanded sales force is gaining traction in the MS market faster than we expected,” commented Steve Cartt, Executive Vice President and Chief Business Officer. “We believe the increased physician call activity, as well as further productivity gains by our sales personnel will drive continued MS sales growth throughout 2011.”

“During March, we initiated a limited selling effort in nephrology and a peer-reviewed journal published the first clinical data supporting the use of Acthar in the treatment of nephrotic syndrome. Our NS sales team has generated encouraging early Acthar prescription activity and we are now beginning to explore options for increasing our sales effort in this market,” concluded Mr. Cartt.

Sales Reserves

Questcor’s sales reserves during the quarter ended March 31, 2011, including the Company’s reserves for Medicaid rebates, represented 24.3% of Gross Sales of $48.6 million for the quarter ended March 31, 2011.

As required by federal regulations, Questcor provides rebates to state Medicaid programs for Acthar dispensed to Medicaid patients covered under Medicaid rebate-eligible insurance plans. Since the Company does not receive rebate claims from the various state Medicaid agencies until well after the close of the quarter in which the underlying sales took place, the Company establishes reserves for expected rebate claims on a quarterly basis. As a result of the adoption of health care reform, for

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periods after March 23, 2010, the Company has also included in this reserve an estimate for the liability due to states related to prescriptions of Acthar for patients covered under state Medicaid Managed Care Organizations (Medicaid MCO), which prescriptions were not previously rebate eligible.

Operating Expenses

Operating expenses were $18.6 million for the quarter ended March 31, 2011, compared to $12.2 million for the quarter ended March 31, 2010. The year-over-year growth in expenses was principally due to increased headcount-related costs, including sales commissions, and expenses associated with marketing programs. In addition, the Company incurred an expense of approximately $0.3 million for the write-off of goodwill associated with a 1999 acquisition.

The Company expects operating expenses to continue to increase during 2011, due to increased spending associated with its Phase IV clinical study of the use of Acthar in the treatment of NS associated with idiopathic membranous nephropathy and increased selling and marketing expenses.

Cash and Share Repurchase Program

As of April 22, 2011, Questcor’s cash, cash equivalents and short-term investments totaled $128 million.

During the first quarter, the Company used $11.5 million to repurchase 884,300 shares of its common stock in open market transactions. These repurchases brought the total expenditures for the repurchase of common and preferred shares to over $78 million since this effort began in 2008. As of March 31, 2011, Questcor had 61.7 million shares of common stock outstanding, with 4.3 million shares remaining under its common stock repurchase program.

Conference Call Details

The Company will host a conference call today, April 26, 2011 at 4:30 p.m. ET/ 1:30 p.m. PT, to discuss first quarter 2011 results. Don Bailey, President and Chief Executive Officer, and other members of the management team will host the call.

To participate in the live call by telephone, please dial 877-941-1465 for domestic participants and 480-629-9678 for international participants. Participants are asked to call the above numbers 5-10 minutes prior to the starting time. The call will also be webcast live at www.questcor.com. An audio replay of the call will be available for 7 days following the call. This replay can be accessed by dialing 800-406-7325 for domestic callers and 303-590-3030 for international callers, both using passcode 4434709#. An archived webcast will also be available at www.questcor.com.

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About Questcor

Questcor Pharmaceuticals, Inc. is a biopharmaceutical company whose primary product helps patients with serious, difficult-to-treat medical conditions. 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 acute exacerbations of multiple sclerosis in adults, the treatment of nephrotic syndrome, 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 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. Questcor also markets Doral^(R) (quazepam), which is indicated for the treatment of insomnia characterized by difficulty in falling asleep, frequent nocturnal awakenings, and/or early morning awakenings. For more information, 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:

Questcor Pharmaceuticals, Inc.

Don Bailey

714-786-4210

dbailey@Questcor.com

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Questcor Pharmaceuticals, Inc.

Consolidated Statements of Income

(In thousands, except per share amounts)

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Net income per share applicable to common shareholders – 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)

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