The Tepezza class action lawsuit is not actually a class action. It is a federal multidistrict litigation (MDL No. 3079) in the Northern District of Illinois that consolidates roughly 277 individual cases from patients who say the thyroid eye disease drug Tepezza caused permanent hearing loss or tinnitus. No trials have happened yet, no settlements have been announced, and the first bellwether trial is currently scheduled for August 3, 2026.
If you took Tepezza and later developed hearing problems, that distinction matters. You would file your own lawsuit, not join a group. Here is what the litigation involves and what a potential claim looks like.
Why It’s an MDL and Not a Class Action
People searching for a “Tepezza class action” are almost always looking for the mass litigation against manufacturer Horizon Therapeutics, now owned by Amgen. That litigation exists, but it is structured as multidistrict litigation.
The difference is practical. In a class action, a few named plaintiffs represent everyone in the class, and one settlement or verdict binds the group. In an MDL, each plaintiff keeps a separate case. The court consolidates the cases only for shared pretrial work: discovery, coordinated motions, and a small number of test trials called bellwethers. Damages are evaluated one plaintiff at a time.
The Judicial Panel on Multidistrict Litigation created this MDL in mid-2023. It is officially titled In Re: Tepezza Marketing, Sales Practices, and Products Liability Litigation, MDL No. 3079, Master Case No. 1:23-cv-03568, and is overseen by U.S. District Judge Thomas M. Durkin.
What the Lawsuits Allege
Tepezza (teprotumumab-trbw) is an intravenous infusion approved by the FDA on January 21, 2020, as the first drug specifically indicated for thyroid eye disease. When it launched, the label warned about infusion reactions and inflammatory bowel disease flare-ups. It said nothing specific about severe or permanent hearing damage.
In July 2023, the FDA required a label update stating that Tepezza “may cause severe hearing impairment including hearing loss, which in some cases may be permanent,” and directing doctors to test patients’ hearing before, during, and after treatment. Plaintiffs argue Horizon knew the risk well before that update.
The reported injuries include permanent hearing loss, tinnitus, muffled hearing, autophony (hearing one’s own voice abnormally loudly), eustachian tube dysfunction, and hypersensitivity to sound. Horizon’s own website acknowledges that about one in ten patients in earlier clinical studies reported hearing issues, with a more recent study of patients with longer-standing thyroid eye disease putting the rate closer to two in ten.
The complaints generally raise three theories:
- Failure to warn. The core claim in most cases. Plaintiffs allege Horizon had clinical trial data, adverse event reports, and internal safety concerns tying Tepezza to permanent hearing damage, but did not disclose those risks to patients, prescribers, or regulators in time. Some complaints allege the company described hearing side effects as temporary when they could be permanent.
- Defective design. Some plaintiffs allege Horizon should have developed a safer formulation before seeking FDA approval. Judge Durkin ruled in November 2023 that these pre-approval design defect claims were not blocked by federal preemption. He later dismissed post-approval design defect claims in certain bellwether cases.
- Negligent marketing. Plaintiffs contend Horizon promoted Tepezza as a groundbreaking therapy while withholding information about irreversible hearing damage. Some complaints add fraudulent misrepresentation and allege the company retaliated against internal whistleblowers who raised safety concerns.
Plaintiffs are seeking compensatory damages for medical expenses, lost wages, and diminished quality of life, plus punitive damages for what they describe as knowing concealment.
Who Can File a Tepezza Claim
To pursue a case, you generally need to show three things.
You received Tepezza. Medical records documenting the infusions, typically at least two, are the starting point.
You have a diagnosed auditory injury. Hearing loss, tinnitus, or a related impairment, backed by audiograms and hearing tests.
The timing fits. Symptoms should have started during or after Tepezza treatment. Research indicates symptoms commonly appear between the third and fifth infusions, but they can show up at any point during or after the treatment course.
One practical note on evidence: plaintiffs argue that standard audiograms can miss the damage Tepezza causes, because drug-related ototoxicity often first appears at ultrahigh frequencies above 8 kHz, which conventional hearing tests do not measure. If your regular hearing test came back normal but you have real symptoms, that gap is part of the plaintiffs’ case.
Filing Deadlines Vary by State
Product liability statutes of limitations generally run one to six years, with most states falling in the two-to-three-year range measured from when the injury was discovered. Some states also impose a statute of repose, which is an absolute outer deadline measured from the date of purchase or use.
Because Tepezza’s label did not warn about severe hearing damage until July 2023, the “discovery rule” in many states may extend your filing window if you did not previously connect your hearing problems to the drug. Consult a lawyer in your state promptly; waiting can foreclose the claim.
One State-Specific Boundary Worth Knowing
Michigan plaintiffs whose injuries occurred before February 13, 2024 face a serious obstacle. Michigan had a statute, Mich. Comp. Laws Ann. § 600.2946, shielding FDA-approved drug manufacturers from product liability suits. The state repealed it effective February 13, 2024, but Judge Durkin held that the repeal is not retroactive. In October 2024 he dismissed one bellwether case, brought by plaintiff Cherl Merriweather, on that basis.
Where the Cases Stand Now
Roughly 273 to 277 cases were pending in early 2026. Fact discovery has closed, and expert depositions were completed in 2025.
The court selected 12 bellwether discovery cases using a “4/4/4” model, with plaintiffs, Horizon, and the court each picking four. After the Merriweather dismissal, 11 remain, and four are designated to go to trial. Based on the current schedule set by an August 2025 court order, those four trials are set for:
- August 3, 2026
- September 28, 2026
- November 30, 2026
- February 1, 2027
Each is expected to last three to four weeks. The trial calendar has shifted before. In October 2025, after an off-the-record conference with Chief Magistrate Judge M. David Weisman, the court vacated the then-existing bellwether trial deadlines, prompting speculation about settlement talks. The court has required both sides to hold quarterly settlement negotiations.
Two pretrial rulings matter for anyone considering a claim. In November 2023, the court kept the pre-approval design defect theory alive by rejecting Horizon’s preemption argument. In January 2025, the court denied Horizon’s motion to dismiss the failure-to-warn claims in the bellwether cases, leaving the central theory of liability intact.
What a Payout Might Look Like
There are no established Tepezza settlement figures. No trials have finished, and no global settlement has been announced. Estimates circulated by legal commentators run from about $50,000 to more than $1 million per case, driven mostly by injury severity.
What is likely to matter in valuing individual claims: the permanence and degree of hearing loss, out-of-pocket costs such as hearing aids, lost income, and how bellwether juries respond to the medical evidence and to Horizon’s conduct. Recovery rates from Tepezza-related injuries also vary by symptom. Tinnitus resolves in most patients who stop the drug, but only about 46% of patients with sensorineural hearing loss see improvement after discontinuation, according to a 2026 meta-analysis published in Cureus.
The MDL is smaller than many mass torts, with under 300 cases as of 2026. Some legal observers have suggested that a smaller plaintiff pool could translate to higher individual payouts if a global settlement is reached, since any total fund would be divided among fewer claimants. That remains speculation until a trial verdict or settlement provides a benchmark.
If you think you have a claim, the practical next step is to gather your infusion records and hearing test results and speak with a product liability attorney about the deadline in your state.