Mounjaro, a breakthrough drug for type 2 diabetes and weight loss, has been making headlines. What’s going on with Mounjaro in 2025?
From new warnings to lawsuits and global expansion, this article explains the latest developments in simple terms.
What is Mounjaro?
Mounjaro, developed by Eli Lilly, contains tirzepatide, a dual GLP-1 and GIP receptor agonist. It’s FDA-approved for managing type 2 diabetes in adults and is used off-label for weight loss. Its sister drug, Zepbound, is approved for obesity management.
The drug mimics two gut hormones to regulate blood sugar and appetite. It slows digestion, boosts insulin production, and reduces hunger, leading to weight loss. Mounjaro is a weekly injection, typically administered under the skin.
New FDA Warnings and Side Effects
In 2025, Eli Lilly updated Mounjaro’s label with stronger warnings for serious side effects. These include pancreatitis, acute kidney injury due to dehydration, and diabetic retinopathy complications in patients with a history of this condition. The updates aim to improve patient safety.
A recent study also linked tirzepatide to a rare eye condition called nonarteritic anterior ischemic optic neuropathy (NAION). This can cause vision loss and wasn’t initially listed on Mounjaro’s label. Patients with eye issues should discuss risks with their doctor.
Why the Updated Warnings?
The FDA and Eli Lilly strengthened warnings after reports of severe side effects. Pancreatitis, a painful inflammation of the pancreas, has been reported in some users. Dehydration from nausea or vomiting can also harm kidneys, especially in those with pre-existing conditions.
The NAION link emerged from a 2025 study in JAMA Ophthalmology. Though rare, the risk prompted calls for better labeling. These updates reflect ongoing efforts to monitor Mounjaro’s safety as more patients use it.
Other Known Side Effects
Mounjaro’s side effects are mostly digestive and often mild. They tend to lessen over time with proper management. However, some risks are more serious and require attention.
Common side effects include:
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Stomach pain
Mounjaro also has a boxed warning for thyroid tumors, including cancer, based on animal studies. It’s not clear if this applies to humans. Patients with a history of thyroid cancer or endocrine conditions should avoid it.
Lawsuits Against Eli Lilly
What’s going on with Mounjaro also involves legal challenges. By June 2025, 1,882 lawsuits were pending in a federal multidistrict litigation (MDL) against Eli Lilly. Patients claim the company didn’t adequately warn about side effects like gastroparesis, a condition causing stomach paralysis.
Some lawsuits involve wrongful death claims, alleging severe complications like intestinal blockages led to fatalities. The MDL is preparing for bellwether trials in late 2025, with a key hearing on gastroparesis diagnosis set for May. These cases highlight concerns about Mounjaro’s risks.
Supply Issues and Shortages
Mounjaro has faced supply challenges due to high demand. In Australia, all vial doses are unavailable until August 31, 2025, though the KwikPen version is accessible. The FDA declared the U.S. shortage resolved in April 2025, but intermittent backorders persist.
Eli Lilly has invested $23 billion to boost production globally. New facilities in the U.S., Ireland, Italy, and Spain aim to meet demand. Patients should check with pharmacies and consider switching to the KwikPen if vials are unavailable.
Global Expansion Plans
Eli Lilly plans to launch Mounjaro in major emerging markets like China, India, Brazil, and Mexico by late 2025. This targets a potential 900 million patients, driven by rising diabetes and obesity rates. The rollout follows a limited launch in China in 2024.
The expansion will compete with Novo Nordisk’s Wegovy and Ozempic. Mounjaro’s dual-hormone action gives it an edge in weight loss, boosting its appeal. However, supply constraints could limit access in these markets initially.
Mounjaro vs. Wegovy: The Weight Loss Race
A 2025 head-to-head trial showed Mounjaro outperforms Wegovy for weight loss. After 72 weeks, Mounjaro users lost 20% of their body weight, compared to 14% for Wegovy. This has fueled its popularity, especially for off-label use.
Mounjaro’s dual GLP-1 and GIP action suppresses appetite more effectively than Wegovy’s single GLP-1 mechanism. However, Wegovy is approved for heart risk reduction, which Mounjaro isn’t. Patients should discuss which drug suits their needs with their doctor.
Table: Mounjaro vs. Wegovy Comparison
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Active Ingredient | Tirzepatide (GLP-1 and GIP agonist) | Semaglutide (GLP-1 agonist) |
| Average Weight Loss | 20% (72 weeks) | 14% (72 weeks) |
| FDA Approvals | Type 2 diabetes, off-label weight loss | Weight loss, heart risk reduction |
| Common Side Effects | Nausea, diarrhea, vomiting | Nausea, vomiting, diarrhea |
How to Use Mounjaro Safely
Using Mounjaro safely requires close medical supervision. Patients should follow their doctor’s instructions and report side effects promptly. Here are some safety tips:
- Monitor Symptoms: Watch for severe stomach pain, vision changes, or dehydration signs.
- Inform Healthcare Providers: Tell your surgical team about Mounjaro use before anesthesia.
- Stay Hydrated: Drink fluids to prevent kidney issues from nausea or vomiting.
- Verify Medication: Get Mounjaro from licensed pharmacies to avoid counterfeits.
Mounjaro’s Benefits
Despite challenges, Mounjaro offers significant benefits. It lowers A1C levels by 75–90% in type 2 diabetes patients, with results seen in 40–52 weeks. Weight loss can reach 25 pounds at higher doses, aiding overall health.
A 2025 study confirmed Mounjaro sustains weight loss for up to three years. This makes it a valuable tool for obesity management when paired with diet and exercise. Its dual-hormone action sets it apart from competitors.
Compounded Tirzepatide Concerns
During shortages, some patients turned to compounded tirzepatide from pharmacies. These versions aren’t FDA-approved and have raised safety concerns. Reports include bacterial contamination, incorrect ingredients, or sugar alcohol instead of tirzepatide.
Australia banned compounded tirzepatide in May 2024 after a patient was hospitalized. The FDA ended enforcement discretion for compounded versions in March 2025. Patients should stick to FDA-approved Mounjaro or Zepbound.
Mounjaro’s Role in the UK
In December 2024, the UK’s NHS approved Mounjaro for obesity in patients with a BMI of 35 or higher and weight-related conditions. A lower BMI threshold applies for certain ethnic groups. The rollout began in June 2025 but faces delays due to service shortages.
Some UK integrated care boards (ICBs) haven’t finalized services, limiting GP prescriptions. Patients with the greatest clinical need can access Mounjaro via specialists. This expansion highlights Mounjaro’s growing global impact.
Patient Experiences and Advocacy
Patients share mixed experiences with Mounjaro. Many praise its weight loss results, with some losing up to 56 pounds. Others face challenges like insurance denials or side effects, prompting calls for better access and education.
Advocacy groups are pushing for transparency in drug labeling and coverage. Social media platforms like Reddit highlight success stories and concerns, fostering community support. Patients are encouraged to report side effects to the FDA’s MedWatch program.
What’s Next for Mounjaro?
Eli Lilly is scaling up production to address shortages. Ongoing research will clarify rare side effects like NAION and gastroparesis. The MDL trials in 2026 may influence future warnings and prescribing practices.
Patients should stay proactive. Regular doctor visits, pharmacy checks, and awareness of side effects ensure safe use. Mounjaro’s global rollout will shape its role in diabetes and obesity care.
Summary
What’s going on with Mounjaro? The drug remains a powerful option for type 2 diabetes and weight loss, but 2025 brought new warnings for pancreatitis, kidney issues, and vision risks. Lawsuits claim inadequate warnings for side effects like gastroparesis, while shortages and compounded drug concerns persist.
Eli Lilly’s global expansion and Mounjaro’s edge over Wegovy highlight its potential. Patients can use Mounjaro safely by staying informed and working with their doctor.
FAQ
What are the new warnings for Mounjaro in 2025?
Mounjaro’s label now includes stronger warnings for pancreatitis, acute kidney injury, and diabetic retinopathy complications. A study also linked it to NAION, a rare eye condition causing vision loss. Discuss risks with your doctor.
Is Mounjaro still in shortage?
The FDA resolved the U.S. shortage in April 2025, but intermittent backorders occur. In Australia, vials are unavailable until August 2025. Check with pharmacies and consider the KwikPen version.
Why are there lawsuits against Mounjaro?
Over 1,800 lawsuits claim Eli Lilly didn’t warn about side effects like gastroparesis and intestinal blockages. Some involve wrongful death claims. Trials are set for late 2025 in a federal MDL.
How does Mounjaro compare to Wegovy?
Mounjaro led to 20% weight loss versus Wegovy’s 14% in a 2025 trial. Mounjaro targets GLP-1 and GIP, while Wegovy is GLP-1 only. Wegovy has heart risk approval, unlike Mounjaro.
Can I use compounded tirzepatide safely?
Compounded tirzepatide isn’t FDA-approved and has caused safety issues like contamination. Australia banned it in 2024. Stick to FDA-approved Mounjaro or Zepbound from licensed pharmacies.
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