GLP-1 Drugs Have Been Linked to More Than 200 Reported Deaths in the UK Alone

Regulators say the benefits still outweigh the risks when semaglutide drugs are used properly.

The GLP-1 rush has taken the world by storm. Ozempic, Wegovy and Mounjaro have become household names, while prescriptions for medicines that target GLP-1 have soared.

But scientists never really had time to assess the large-scale impact of this drug rush.

For all the good these treatments can do, they can also be dangerous in some instances. According to a new report, UK regulators have logged more than 158,000 suspected adverse reactions involving three of the best-known drugs in this family. These include more than 200 fatal outcomes.

But this doesn’t mean Ozempic killed 200 people. Here’s what that means.

A Sharp Rise in Reports

The Medicines and Healthcare Products Regulatory Agency (MHRA) tracks suspected side effects through its Yellow Card Scheme, a system that allows patients, relatives, and health professionals to flag possible reactions to medicines. Most regulator in the developed world have a similar type of system.

A Yellow Card report doesn’t prove that a medicine caused an illness or death. Someone may report an event because they suspect a connection, but the underlying cause could be another illness, another medicine, or even just coincidence. The MHRA uses these reports to look for safety signals that deserve further investigation.

In total, regulators have received more than 158,000 suspected adverse reaction reports involving three widely used medicines: tirzepatide, semaglutide, and liraglutide. Tirzepatide, sold as Mounjaro, accounts for by far the largest number of suspected reactions among the three medicines. Semaglutide, the active ingredient in Wegovy, Ozempic and Rybelsus, comes next, followed by liraglutide, which includes Saxenda.

This is a steep increase from earlier reports. In February 2025, the BMJ reported that MHRA data through Jan. 31 showed 82 deaths linked in Yellow Card reports to GLP-1 agonists: 22 involving use for weight loss and 60 involving treatment for type 2 diabetes.

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At that point, the reports included 18 deaths involving tirzepatide, 29 involving semaglutide, and 35 involving liraglutide. The BMJ also noted an important gap in the data: the reports did not show whether the medicines came through the NHS, private prescribers, or online sellers.

What the Reports Can and Can’t Show

GLP-1 receptor agonists mimic a hormone released after eating, helping regulate appetite and blood sugar. Tirzepatide works slightly differently because it targets both GLP-1 and another hormone receptor called GIP.

Not every medicine in this group has the same UK authorisation. Wegovy is authorised for weight management, while Ozempic and Rybelsus are semaglutide products authorised for diabetes rather than weight loss. Mounjaro is authorised for both diabetes and weight management.

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The most common side effects are gastrointestinal. Nausea, vomiting and diarrhoea account for a large share of the reports received by the MHRA and are usually mild to moderate or short-lived. In some cases, however, persistent vomiting or diarrhoea can lead to severe dehydration and hospital treatment.

A rarer concern is acute pancreatitis. Between 2007 and October 2025, the regulator received 1,296 Yellow Card reports of pancreatitis involving drugs in these classes. Nineteen had a fatal outcome.

Those risks have to be weighed against substantial benefits. These medicines can produce major weight loss in eligible patients and improve blood-sugar control in people with type 2 diabetes. The MHRA continues to say that, based on current evidence, their benefits outweigh their potential risks when they are used as authorized.

Online Prescribing Raises Concern

Some of the safety risk has little to do with legitimate medicines themselves.

Because demand is surging so much, it’s triggered a lucrative market for illegal and falsified products. In 2023, the MHRA reported finding fake Ozempic and Saxenda pens in the UK, including products that contained insulin instead of the medicine advertised on the label.

Some people who received falsified pens were hospitalised and required urgent treatment, with cases including dangerously low blood sugar and hypoglycaemic shock.

This isn’t a UK-specific problem. All regulators continuously warn people against buying GLP-1 products through social media, unregulated websites or sellers that offer the medicines without a prescription.

Dr Vicky Price, then president-elect of the Society for Acute Medicine, told The BMJ that some patients were obtaining the drugs from “non-reputable sources” and might not be receiving a weight-loss medicine at all. “Patients could then be injecting anything into themselves, including life threatening substances,” she said.

The Bottom Line

For patients, the message from regulators isn’t to stop considering these drugs.

It’s pretty simple, really. Take GLP-1 medicines only when prescribed. Do not change the dose without medical advice. Be alert to persistent or unusually severe symptoms. And report suspected side effects.

The growing pile of safety reports is not proof that GLP-1 medicines have suddenly become unsafe. It is, in part, what happens when a powerful new class of medicines moves from controlled trials into use by millions of people. It’s also a sign that medical and scientific surveillance works to constantly improve drugs.

For all the scrutiny around their risks, GLP-1-based drugs have delivered substantial benefits. Medicines such as semaglutide and tirzepatide can produce weight loss on a scale that is difficult to achieve without bariatric surgery; in major trials, tirzepatide produced average losses approaching 20% of body weight at higher doses. These drugs improve blood-sugar control in people with type 2 diabetes, and semaglutide has been shown to reduce the risk of heart attack, stroke or cardiovascular death in people with obesity or overweight and established cardiovascular disease.

The challenge now is to identify genuine problems quickly — and make sure the drugs can continue to work safely at scale.