By When a drug receives FDA approval, patients and healthcare providers reasonably expect that its known risks have been thoroughly identified and communicated. The tepezza lawsuit challenges that assumption. Patients across the United States who received Tepezza infusions to treat thyroid eye disease have filed legal claims alleging that the drug caused permanent hearing loss and other auditory injuries that were not adequately disclosed before treatment.
For anyone living with thyroid eye disease, or for families navigating the aftermath of an unexpected hearing injury, these legal developments raise important questions about drug safety, informed consent, and the rights of patients harmed by pharmaceutical products. This article explains what this litigation involves, what the science currently suggests, and what affected individuals should know about their options.
Table of Contents
What Is the Tepezza Lawsuit?
The tepezza lawsuit refers to a growing body of personal injury litigation filed against Horizon Therapeutics, the manufacturer of Tepezza (teprotumumab-trbw). According to publicly filed lawsuits, plaintiffs allege that Horizon Therapeutics failed to adequately warn patients and physicians about the risk of permanent hearing loss and tinnitus associated with Tepezza infusion treatment.
These claims are classified as pharmaceutical product liability lawsuits, a category of litigation that arises when a drug or medical device causes harm that the manufacturer knew or should have known about and failed to properly disclose. The tepezza lawsuit does not allege that the drug is ineffective — in fact, many plaintiffs acknowledge that their thyroid eye disease symptoms improved — but rather that the auditory risks were either downplayed or omitted from early warning labels.
As of early 2025, more than 200 individual federal cases had been consolidated into multidistrict litigation in the Northern District of Illinois, with the number continuing to grow as more patients become aware of the connection between Tepezza and hearing damage.
Why Are Patients Filing Tepezza Lawsuits?
Patients are filing tepezza lawsuits primarily because they allege they experienced hearing loss or tinnitus following their infusion treatment and were not warned this could happen. For many, the hearing damage has proven permanent, fundamentally altering their quality of life long after their eye disease was treated.
A central grievance in the tepezza lawsuit is timing. According to filed complaints, the FDA did not add a formal hearing impairment warning to the Tepezza prescribing label until July 2023 — more than three years after the drug was first approved in January 2020. Many plaintiffs allege they received infusions well before that label update and had no opportunity to make an informed decision about the auditory risks involved.
Drug safety litigation of this kind often emerges in a predictable pattern: a drug reaches the market with limited trial data, post-market use reveals adverse effects at higher rates than anticipated, independent research raises questions, and regulatory action eventually follows. Patients harmed in the interval between approval and updated warnings frequently turn to the legal system to seek accountability and compensation.
Understanding Tepezza and Thyroid Eye Disease Treatment
What Is Tepezza (Teprotumumab)?
Tepezza is the brand name for teprotumumab-trbw, a prescription biologic medication administered by intravenous infusion. It was developed to treat thyroid eye disease (TED), a serious autoimmune condition in which the immune system attacks the tissue and muscles surrounding the eye.
TED is most commonly associated with Graves’ disease, a hyperthyroid condition that can cause the eyes to bulge outward, resulting in double vision, pain, inflammation, and in severe cases, vision loss. Before Tepezza, patients had limited treatment options, many of which were surgical or only partially effective.
How the Drug Works
Tepezza works by blocking the insulin-like growth factor-1 receptor (IGF-1R), a protein that plays a significant role in the inflammation driving thyroid eye disease. By inhibiting IGF-1R activity, the drug reduces the tissue expansion and swelling behind the eyes that causes TED’s most debilitating symptoms.
However, IGF-1R receptors are not exclusive to eye tissue. Researchers have noted that these receptors are also present in auditory pathways, including the inner ear. The proposed mechanism in tepezza hearing loss lawsuit claims is that this same receptor-blocking activity may interfere with normal auditory function, potentially causing sensorineural hearing damage in some patients.
FDA Approval and Medical Use
The FDA approved Tepezza in January 2020, making it the first and only approved pharmaceutical treatment specifically indicated for thyroid eye disease. The approval was based on two pivotal clinical trials involving approximately 170 patients. Tepezza quickly became a commercially significant drug, generating over one billion dollars in annual sales.
In those initial clinical trials, hearing impairment was reported in roughly 10% of Tepezza-treated patients, compared to zero among placebo recipients. Critics of the drug’s early rollout have argued that this signal was not adequately emphasized in the original prescribing information and that the clinical trial populations were too small to fully characterize the risk.
Reported Side Effects in Tepezza Lawsuits
Hearing Loss and Tinnitus Claims
The most frequently reported injury in tepezza hearing loss lawsuit filings is sensorineural hearing loss — a form of inner ear damage that affects the ability to perceive sound — and tinnitus, the perception of ringing, buzzing, or other persistent noises in the ears when no external sound is present.
Plaintiffs report that in many cases, their hearing difficulties began during or shortly after the infusion cycle and did not resolve after treatment ended. Some allege that the hearing loss is permanent and has required the use of hearing aids or other assistive devices.
Clinical research published after Tepezza’s approval has suggested that the rate of hearing-related adverse effects may be higher than the 10% reported in pre-approval trials. A 2021 study by the Endocrine Society examining 26 patients found that 65% reported hearing problems, including tinnitus, ear plugging, autophony, and hearing loss. A 2022 observational study published in the American Journal of Ophthalmology reported that approximately 81.5% of participants developed new or worsening hearing symptoms, with less than half of those experiencing resolution after stopping treatment.
These figures are from independent research and involve different study methodologies. They should not be interpreted as definitive population-level incidence rates, but they have contributed significantly to the legal and regulatory scrutiny surrounding this litigation.
Other Reported Side Effects
Beyond hearing-related claims, plaintiffs and clinical sources have documented other adverse effects associated with Tepezza infusions, including:
- Muscle cramps or spasms
- Fatigue and headache
- Hyperglycemia (elevated blood sugar), for which the FDA added a label warning in December 2022
- Infusion reactions
- Exacerbation of inflammatory bowel disease
- Autophony, the abnormal perception of one’s own voice or internal body sounds as unusually loud
Not all patients experience these effects, and individual outcomes vary considerably depending on health history, dosage, and the number of infusions received.
Patient-Reported Experiences
Across filed complaints and publicly available case reports, a consistent pattern emerges: patients who reported auditory symptoms during treatment were often not connected to the drug as a potential cause, and some allege their concerns were initially attributed to other factors. Several plaintiffs have described seeking specialist audiological care only after their infusions were complete, at which point the hearing damage had already progressed.
According to publicly filed lawsuits, patients have described the impact of their hearing injuries in terms of lost employment, communication difficulties, social withdrawal, and diminished quality of life — harms that form the basis of their drug injury compensation claims.
What the Tepezza Lawsuit Alleges
Failure to Warn Claims
The most prominent legal theory in these cases is failure to warn. Under product liability law, pharmaceutical manufacturers have a duty to disclose all known material risks of their drugs to prescribing physicians, who in turn can counsel patients about those risks before treatment begins. This duty exists whether the risk is confirmed or merely reasonably suspected.
Allegations in filed lawsuits claim that Horizon Therapeutics was aware of post-market evidence linking Tepezza to hearing damage — including independent research and patient reports — but did not update its drug label to include a warning until July 2023, more than three years after the drug reached the market. According to these claims, patients who were treated prior to July 2023 were denied the opportunity to make an informed choice about their auditory risk.
Product Liability Allegations
In addition to failure to warn, some complaints include broader product liability allegations, arguing that the drug was defectively designed or that the manufacturer failed to conduct adequate pharmacodynamic testing to identify and characterize the mechanism of hearing damage before market launch. According to court documents filed in one case, the Tepezza prescribing label itself acknowledged that no formal pharmacodynamic studies had been conducted with the drug.
Manufacturer Responsibilities
Horizon Therapeutics was acquired by Amgen Inc. in 2023 in a multi-billion dollar transaction, meaning Amgen now stands as the legal successor to many of the obligations at issue in this litigation. Horizon Therapeutics has previously stated that the lawsuits are without merit and that hearing impairment was identified as a potential adverse event in the pivotal clinical trials and discussed at the FDA advisory committee meeting prior to approval.
The resolution of the failure to warn claims will likely depend heavily on what internal documents show about the company’s awareness of post-market hearing reports and what steps, if any, were taken before the July 2023 label update.
Scientific Research and Clinical Trial Data
Several bodies of research inform the scientific dimension of these claims. In addition to the 2021 Endocrine Society study and the 2022 American Journal of Ophthalmology study, a 2024 meta-analysis pooling data from both randomized and observational research found a statistically significant increase in hearing impairment risk associated with teprotumumab, consistent across multiple study designs.
A separate cohort study using the TriNetX database compared more than 500 Tepezza-treated patients to matched controls and found an approximately threefold increase in the relative risk of sensorineural hearing loss over a five-year observation window.
A 2024 case series following 22 patients found that 39% of ears met accepted ototoxicity criteria for hearing loss, with many patients reporting symptoms that developed gradually and were not captured by standard audiometry. This latter finding has drawn concern from researchers, who have suggested that conventional hearing tests may underestimate the prevalence of Tepezza-related auditory damage.
The FDA’s decision to update the Tepezza prescribing label in July 2023 to include the warning that the drug “may cause severe hearing impairment including hearing loss, which in some cases may be permanent” lends institutional weight to the body of evidence linking the drug to auditory injury. The updated label also directs healthcare providers to assess patients’ hearing before, during, and after treatment.
It is important to note that science in this area continues to evolve. No regulatory agency has confirmed a definitive causal mechanism, and not all patients who receive Tepezza experience hearing-related side effects.
Current Status of Tepezza Litigation
Mass Tort and MDL Overview
The tepezza lawsuit proceedings are organized through a multidistrict litigation (MDL) structure, which is a federal procedural mechanism designed to efficiently manage large numbers of similar lawsuits filed in courts across the country. Under MDL, individual cases are transferred to a single federal judge — in this instance, Judge Thomas Durkin in the Northern District of Illinois — for coordinated pretrial proceedings, including discovery and case management.
It is important to understand that an MDL is not a class action lawsuit. Each plaintiff retains their individual claim and must prove their own specific injuries. The MDL structure simply consolidates the pretrial process to prevent duplicative litigation across multiple courts and to promote consistent rulings on shared legal questions.
As of early 2025, more than 200 federal cases were consolidated in the Tepezza MDL, with new filings continuing to accumulate.
Case Developments and Trends
In June 2024, the court designated 12 cases as a bellwether discovery pool — a standard MDL practice in which a representative group of cases undergoes intensive discovery to prepare them for early trial. Bellwether trials are not binding on all plaintiffs, but their outcomes tend to have a substantial influence on settlement negotiations in mass tort litigation.
Four bellwether trials are anticipated to be scheduled for 2026. Judge Durkin has instructed both parties to meet for settlement discussions at least once per quarter as the litigation advances. No settlements have been publicly announced as of the date of this publication.
Horizon Therapeutics has raised a federal preemption defense in the litigation, arguing that certain state-law failure to warn claims should be barred because the FDA — not the manufacturer — controls drug labeling. This argument is contested and is expected to be a significant legal question resolved during the MDL proceedings.
What Patients Should Know Before Considering Legal Action
Patients who received Tepezza infusions and subsequently experienced hearing loss, tinnitus, or other auditory symptoms may wish to speak with a licensed attorney who handles pharmaceutical injury lawsuits. There is no obligation to file a claim, and initial consultations are typically offered at no cost.
Before taking legal action, it may be helpful to gather relevant documentation, including medical records showing the dates and dosage of Tepezza infusions, records of any audiological evaluations, a documented history of hearing symptoms, and records of medical care received for those symptoms.
Individuals with pre-existing hearing conditions should be aware that this may complicate a claim, though it does not necessarily disqualify one. Attorneys evaluating tepezza lawsuit eligibility will typically assess the timing of hearing changes relative to infusions, the nature of the symptoms, and the extent of any documented injury.
Statutes of limitations — legal deadlines for filing personal injury claims — vary by state and generally begin running from the date of injury or the date the plaintiff reasonably discovered the injury. Anyone considering a tepezza lawsuit should consult with an attorney promptly to avoid missing applicable deadlines.
Patients should continue following their current medical treatment plan and consult their physician before making any changes to medication. Filing a lawsuit does not require discontinuing medical care.
How Compensation May Work in Drug Injury Cases
In pharmaceutical product liability cases, plaintiffs generally seek compensation for a range of economic and non-economic damages. Common categories of drug injury compensation claims include:
- Medical expenses – Costs of audiological testing, hearing aids, specialist visits, and ongoing care related to the alleged injury
- Lost income – Wages lost if hearing impairment affects a plaintiff’s ability to work
- Pain and suffering – Non-economic damages for the physical and emotional impact of permanent hearing loss
- Loss of enjoyment of life – Compensation for the diminishment of daily activities and personal relationships caused by the injury
- Punitive damages – In cases where misconduct is proven, courts may award additional damages designed to punish the defendant and deter similar behavior
Compensation amounts in pharmaceutical mass tort cases vary widely depending on the severity of the injury, the strength of the evidence, and the outcome of bellwether trials or settlement negotiations. Attorney estimates cited in publicly available sources suggest that favorable Tepezza hearing loss cases could have potential settlement values in the range of $140,000 to $500,000, though these figures are speculative and individual outcomes are not guaranteed.
Most pharmaceutical injury attorneys handle these cases on a contingency fee basis, meaning no upfront legal fees are required and attorneys are only paid if compensation is recovered.
Key Takeaways for Readers
- The tepezza lawsuit centers on allegations that Horizon Therapeutics failed to adequately warn patients about the risk of permanent hearing loss and tinnitus linked to Tepezza infusions.
- Tepezza received FDA approval in January 2020 as the first treatment specifically approved for thyroid eye disease. The FDA did not add a hearing impairment warning to the label until July 2023.
- According to publicly filed lawsuits, plaintiffs allege that Horizon knew or should have known about the auditory risks well before the label update and failed to act promptly.
- Independent clinical studies have suggested hearing-related adverse effects may occur at higher rates than the 10% reported in pre-approval trials, though research in this area is ongoing.
- As of early 2025, more than 200 federal tepezza lawsuit cases are consolidated in multidistrict litigation in the Northern District of Illinois, with bellwether trials anticipated in 2026.
- Patients who received Tepezza and experienced hearing symptoms should consult a licensed pharmaceutical injury attorney to understand their rights and applicable legal deadlines.
- No global settlement has been announced, and individual compensation outcomes in the tepezza lawsuit cannot be predicted or guaranteed.
- Patients should not alter their medical treatment without consulting their physician, regardless of any legal considerations.
Frequently Asked Questions
What is the Tepezza lawsuit about?
The tepezza lawsuit involves personal injury claims filed against Horizon Therapeutics (now part of Amgen) by patients who allege that Tepezza infusions caused permanent hearing loss and tinnitus. Plaintiffs allege that the manufacturer failed to adequately warn patients and prescribing physicians about the risk of auditory damage, particularly before the FDA required a hearing impairment warning to be added to the drug’s label in July 2023.
Does Tepezza cause hearing loss?
Clinical studies have suggested an association between Tepezza (teprotumumab) and hearing-related adverse effects, including sensorineural hearing loss and tinnitus. In pre-approval trials, hearing impairment was reported in approximately 10% of Tepezza-treated patients. Independent studies published after approval have reported higher rates. The FDA formally acknowledged the risk in July 2023 by updating the Tepezza prescribing label to warn that the drug may cause severe hearing impairment, which in some cases may be permanent. Not all patients who receive Tepezza experience hearing problems, and individual outcomes vary.
Who is eligible to file a Tepezza lawsuit?
Eligibility for the tepezza lawsuit generally requires that a person received Tepezza infusions and subsequently experienced hearing loss, tinnitus, or related auditory symptoms. A pharmaceutical injury attorney can evaluate individual circumstances, including the timing of symptoms relative to infusions, prior hearing history, and applicable statute of limitations deadlines. Patients with pre-existing hearing conditions may still be eligible depending on the specifics of their case.
Is there a settlement in the Tepezza lawsuit?
As of the date of this publication, no global or publicly announced settlement has been reached in the tepezza lawsuit MDL. Bellwether discovery is ongoing, with initial trial dates anticipated in 2026. Judge Durkin has directed both parties to engage in settlement discussions quarterly. Settlement negotiations in MDL cases typically intensify after bellwether trial outcomes provide both sides with a clearer picture of jury reactions to the evidence.
What are the most common side effects reported in Tepezza lawsuits?
The most frequently cited side effects in filed claims are permanent hearing loss and tinnitus. Other auditory symptoms reported by plaintiffs include autophony, a sensation of ear fullness, and eustachian tube dysfunction. Additional side effects documented in clinical literature include hyperglycemia, muscle cramps, fatigue, and infusion reactions. Not all patients experience these effects.
How do mass tort Tepezza cases work?
Mass tort Tepezza cases are consolidated through an MDL, which places all federal cases before a single judge in the Northern District of Illinois for coordinated pretrial proceedings. Unlike a class action, each plaintiff maintains their individual claim. The court selects a small number of representative bellwether cases to go through full discovery and trial. The outcomes of these bellwether trials — while not binding on all plaintiffs — typically provide a framework for global settlement negotiations. Each plaintiff’s compensation, if any, is determined individually based on the specific facts of their injury and treatment history.