Sanofi S.A. Class Action Lawsuits and Settlements

Sanofi has faced a long run of class action lawsuits and settlements in the United States, spanning pediatric vaccine antitrust, gender discrimination in its sales force, insulin pricing, Zantac cancer claims, 340B drug discount restrictions, and securities fraud. The company and its U.S. subsidiaries — Sanofi-Aventis U.S. LLC, Sanofi Pasteur Inc., Genzyme Corporation, and Sanofi US Services Inc. — have paid hundreds of millions of dollars to resolve these cases, and since 2000 have accumulated roughly $1.7 billion in penalties across about 40 enforcement actions when government fraud and FCPA matters are added in.¹ Several of the largest matters are resolved; others, including insulin pricing and 340B antitrust claims, remain active.

Pediatric Vaccine Antitrust: Castro v. Sanofi Pasteur

The largest pure class action settlement involving Sanofi came out of the pediatric vaccine market. In Castro v. Sanofi Pasteur Inc. (No. 2:11-cv-07178, D.N.J.), doctors and other vaccine purchasers alleged Sanofi used anticompetitive bundling contracts to protect its meningococcal vaccine Menactra after Novartis launched a competing product, Menveo.² According to the complaint, Sanofi bundled Menactra with pediatric vaccines that had no adequate substitutes, including Pentacel and ActHIB, and customers who bought the Novartis product faced price increases of 15% to 34% across all Sanofi vaccines they purchased.³

Judge Madeline Cox Arleo certified a class of more than 26,000 pediatricians, medical practices, distributors, and health systems in September 2015.² In January 2017, Sanofi agreed to pay $61.5 million, about 14% of the estimated $439 million in alleged overpayments, with no admission of wrongdoing. As part of the deal, Sanofi also dropped a 2012 counterclaim that had accused the plaintiff class of unlawful collective purchasing through physician buying groups.³ The court granted final approval in October 2017.

Gender Discrimination: Bellifemine v. Sanofi-Aventis

In March 2007, female sales representatives filed a nationwide class action in the Southern District of New York alleging systemic gender discrimination. Bellifemine v. Sanofi-Aventis U.S. LLC (No. 1:07-cv-02207) was brought under Title VII and New York state law on behalf of about 5,262 women.⁴ The complaint alleged discrimination in hiring, pay, promotions, evaluations, and training, along with sexual harassment and retaliation for reporting it. Sanofi denied liability.⁵

The court denied Sanofi’s motion to dismiss in February 2008, and the parties settled the following year. On August 5, 2010, Judge John G. Koeltl granted final approval of a $15.36 million settlement.⁶ The fund paid roughly $8.19 million in individual awards (split between a pay disparity regression analysis and a claim-form survey), about $2.05 million into a pay equity fund described as producing a $13.4 million reverberating effect over five years, $4.59 million in attorney fees, and $535,000 in service payments. Sanofi also had to develop and implement new anti-discrimination, harassment, and retaliation policies and improved pay and promotion standards, with the injunctive relief binding for three years. The case was dismissed with prejudice and closed in 2013.⁵

Insulin Pricing Litigation

Sanofi is a central defendant in ongoing litigation over insulin list prices. Consumers in In re Insulin Pricing Litigation (No. 2:17-cv-00699, D.N.J.) alleged that Sanofi and other manufacturers conspired with pharmacy benefit managers to inflate list prices by paying secret rebates in exchange for favorable formulary placement.⁷

In January 2024, the court denied class certification, finding the plaintiffs’ theory that insulin prices were “unfair or unconscionable” because they excluded rebates was not suitable for class-wide treatment. The Third Circuit denied an immediate appeal. Plaintiffs filed a fourth amended complaint in March 2024, and in December 2024 the court granted the defendants’ motion to dismiss in part and denied it in part, letting some claims proceed. The litigation continues.⁸

In August 2023, the Judicial Panel on Multidistrict Litigation consolidated a broader set of insulin pricing cases as MDL No. 3080 before Judge Brian R. Martinotti in the District of New Jersey. That docket now includes the consumer class action along with state attorney general actions, direct purchaser claims, and private RICO, antitrust, and consumer protection suits.⁷

Zantac Cancer Claims

Sanofi is one of several manufacturers named in mass litigation alleging that Zantac, the heartburn drug whose active ingredient ranitidine can degrade into the probable carcinogen NDMA, caused cancer. Sanofi withdrew its over-the-counter version in 2019, and the FDA ordered ranitidine products off the market in 2020.⁹ Nearly 75,000 individual plaintiffs filed personal injury claims.¹⁰ These are individual product liability suits rather than a single certified class, but the volume and consolidated procedures put them in the same practical category.

In December 2022, Judge Robin Rosenberg, presiding over federal MDL 2924 in the Southern District of Florida, excluded all of the plaintiffs’ general causation experts under Daubert, ending roughly 50,000 federal claims. The Eleventh Circuit heard oral arguments on the appeal in October 2025 but had not ruled as of mid-2026.¹¹¹⁰¹²

Even while winning on the science, Sanofi settled about 4,000 state-court cases in April 2024 for roughly $100 million and later agreed to pay between $200 million and $250 million to resolve more than 10,000 additional claims. The company said the claims lacked merit and that it settled to avoid “the expense and ongoing distraction of the litigations.”⁹ Cases remain in California, Illinois, and other state courts, and the Eleventh Circuit appeal could reopen the federal track.

340B Drug Discount Antitrust: Mosaic Health v. Sanofi

A newer class action front involves the federal 340B Drug Discount Program, which requires manufacturers to offer discounts to safety-net hospitals and clinics. Beginning in late 2020, Sanofi and other insulin makers imposed conditions that limited or eliminated 340B pricing when drugs were dispensed through contract pharmacies rather than directly by the covered entity.

In Mosaic Health, Inc. v. Sanofi-Aventis U.S., LLC (No. 24-598), two safety-net providers alleged that Sanofi, Eli Lilly, Novo Nordisk, and AstraZeneca engaged in a horizontal price-fixing conspiracy under the Sherman Act by coordinating to restrict 340B discounts on diabetes drugs. The district court dismissed the complaint for failing to plausibly allege a conspiracy. On August 6, 2025, the Second Circuit vacated the dismissal and remanded, holding that the plaintiffs had adequately alleged parallel conduct — the defendants implemented similar restrictive policies within a four-month window, cutting discounted drug volume by 60% to 90% — along with additional factors supporting an inference of coordination.¹³ The American Hospital Association has separately urged the FTC and DOJ to investigate the manufacturers’ conduct.¹⁴

Securities Fraud Class Actions

Sanofi has faced at least two securities fraud class actions in the Southern District of New York, both of which were dismissed.

In Tongue v. Sanofi (No. 15-588-CV), consolidated complaints filed in December 2013 alleged that Sanofi and its executives made misleading statements about the clinical testing of Lemtrada, a multiple sclerosis drug acquired in the 2011 Genzyme purchase. Investors said optimistic statements about single-blind studies inflated the value of contingent value rights issued in the acquisition; those rights fell from $2.00 to $0.32 per share after the FDA signaled skepticism and rejected the initial application. On March 4, 2016, the Second Circuit affirmed dismissal, holding that no reasonable investor would have been misled because the FDA’s preference for double-blind studies was public and Sanofi had been transparent about its methodology.¹⁵

In Smith v. Sanofi-Aventis (No. 08-00021), shareholders alleged securities fraud related to the anti-obesity drug rimonabant (Zimulti), claiming Sanofi failed to disclose that it tended to cause depression. In September 2009, Judge George B. Daniels dismissed the case, ruling that the challenged statements were unactionable opinions or protected forward-looking statements and that the plaintiffs had not adequately alleged intent to defraud.¹⁶

Government Fraud and FCPA Settlements

Sanofi has paid hundreds of millions more to resolve government fraud allegations. These are not class actions, but they often surface in the same searches and account for the bulk of the company’s U.S. penalty total.

Hyalgan kickback scheme (2012): Sanofi US paid $109 million to resolve allegations that between 2005 and 2009 it provided “free samples” of the knee injection Hyalgan to induce physicians to buy the product and then submitted average sales price reports that ignored the giveaways, inflating Medicare and Medicaid reimbursements. The whistleblower received more than $18.5 million, and Sanofi entered a Corporate Integrity Agreement with HHS.¹⁷¹⁸
Medicaid best-price fraud (2009): Aventis Pharmaceutical paid $95.5 million to settle allegations that it submitted false “best price” reports for Azmacort, Nasacort, and Nasacort AQ between 1995 and 2000 by using sham private label repackaging agreements with Kaiser Permanente. No admission of wrongdoing.¹⁹
Seprafilm off-label promotion (2015): Sanofi subsidiary Genzyme paid a $32.5 million criminal penalty and $22.2 million in civil settlements over allegations that sales representatives promoted converting Seprafilm, an adhesion barrier approved only for open abdominal surgery, into a “slurry” for laparoscopic use. Genzyme entered a deferred prosecution agreement.²⁰
Lemtrada copay kickbacks (2020): Sanofi paid $11.85 million to resolve allegations that it funneled kickbacks to Medicare patients through a purportedly independent charity, The Assistance Fund, to induce Lemtrada purchases. A whistleblower received about $2.7 million.²¹
VA drug overcharges (2017): Sanofi Pasteur paid $19.9 million to resolve allegations that it overcharged the Department of Veterans Affairs for drugs between 2002 and 2011.²²
FCPA (2018): Sanofi paid more than $25 million to resolve SEC charges that subsidiaries in Kazakhstan and the Middle East used distributor kickback schemes (tracked internally as “marzipans”) and “pay-to-prescribe” programs to bribe government officials and prescribers. The penalty included $17.5 million in disgorgement, $2.7 million in prejudgment interest, and a $5 million fine, resolved through a cease-and-desist order without admitting or denying the findings.²³

1
Good Jobs First. Violation Tracker – Sanofi
2
Berger Montague. Castro v. Sanofi Pasteur Inc.
3
Fierce Pharma. Sanofi Agrees to $61.5M Settlement in Vaccine Bundling Class Action Suit
4
Bloomberg Law. Court Approves $15.3 Million Settlement of Sanofi-Aventis Representatives Bias Suit
5
Civil Rights Litigation Clearinghouse. Bellifemine v. Sanofi-Aventis U.S. LLC
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CourtListener. Bellifemine v. Sanofi-Aventis U.S. LLC Docket
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Judicial Panel on Multidistrict Litigation. MDL 3080 Transfer Order
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Keller Rohrback. Insulin Overpricing
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Fierce Pharma. Sanofi’s Zantac Settlement Was $100M
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Delaware Supreme Court. In re Zantac (Ranitidine) Litigation
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MDL Update. MDL 2924 Zantac
12
Verus LLC. Zantac Lawsuit Status for Law Firms
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U.S. Court of Appeals for the Second Circuit. Mosaic Health v. Sanofi-Aventis Circuit Opinion
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American Hospital Association. AHA Letter to FTC and DOJ re Anticompetitive Activity by Drug Companies
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Burr & Forman. Second Circuit Affirms District Court in Tongue v. Sanofi
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CaseMine. Smith v. Sanofi-Aventis Memorandum Opinion
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PR Newswire. $109 Million Settlement With Sanofi-Aventis in False Claims Act Case
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Sanofi US. Sanofi US Reaches Settlement Agreement on Hyalgan
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U.S. Department of Justice. Aventis Pharmaceutical to Pay U.S. $95.5 Million to Settle False Claims Act Allegations
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U.S. Department of Justice. Genzyme Corporation Deferred Prosecution Agreement
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U.S. Department of Justice. Sanofi Agrees to Pay $11.85 Million to Resolve Allegations It Paid Kickbacks Through Co-Pay Assistance
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Knowledge Ecology International. Sanofi False Claims Act Settlements
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U.S. Securities and Exchange Commission. SEC Press Release 2018-174