GLP-1 weight-loss drugs may be linked to more than 150 deaths.
Data from the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA), specifically its Yellow Card Biobank, suggests that GLP-1s are not only linked to deaths but thousands of instances of other, less serious symptoms, such as gastrointestinal issues and nervous system disorders.
Fatalities following GLP-1 use
Thousands of adverse reactions to GLP-1 drugs on MHRA’s Yellow Card Biobank, specifically liraglutide, semaglutide and tirzepatide, were reported. 153 were linked to fatalities.
According to MHRA’s data, 37 deaths were suspected of being linked to semaglutide, with a further 18 linked to liraglutide. A total of 98 deaths were suspected of being linked to tirzepatide.
Yellow Card Biobank also records 28 deaths that took place following people taking exenatide, three for dulaglutide and two for lixisenatide, although these are not commonly used for weight loss.
Semaglutide is available under the brand names Ozempic and Wegovy, sold by Novo Nordisk. Tirzepatide is available under the brand name Mounjaro, sold by Eli Lilly. And liraglutide is known by brand names such as Victoza and Saxenda, sold by Novo Nordisk.
The link between these deaths and symptoms and GLP-1 use was not conclusive, and it is possible they could have unrelated causes.
Other symptoms
Thousands experienced other symptoms. Gastrointestinal disorders were particularly common. Nearly 28,000 people experienced gastrointestinal disorders after taking semaglutide, for tirzepatide, more than 63,000 did, and for liraglutide there were 1,095 reports.
People also experienced nervous system disorders. Nearly 5,000 reported experiencing them these after using semaglutide and more than 10,000 on tirzepatide reported them.
More than 2,200 psychiatric disorders were reported in connection with tirzepatide, more than 1,300 with semaglutide, and 138 for liraglutide.
Nevertheless, the numbers presented here only represent a fraction of those using the drugs in the UK, suggesting that adverse reactions are very rare.
According to the think tank The Food Foundation, nearly 7% of the UK’s population are either currently using the drugs or have used them in the past. A study by University College London (UCL) estimated that 1.6m people in England, Scotland and Wales used Wegovy or Mounjaro to lose weight in 2024 and early 2025.
Major producers of GLP-1s, such as Novo Nordisk, have commented on the data. “At Novo Nordisk we care deeply about patient safety. Like all medicines, treatments used for chronic conditions can have side effects, and these can vary from person to person. That is why medicines should be prescribed by, and used under the supervision of, a healthcare professional, who can consider the potential benefits and risks for each individual”, says a Novo Nordisk spokesperson.
“Patient safety is Lilly’s top priority. We take reports regarding patient safety seriously and actively monitor, evaluate, and report safety information for all our medicines”, says a spokesperson for Eli Lilly.
The spokesperson recommends that Mounjaro should only be used when proscribed by a healthcare professional, and that adverse reactions should be reported to MHRA Yellow Card in the UK, and that and a healthcare professional should be consulted. The spokesperson stresses that the MHRA states reported reactions are not proven to be related to the drug, and should not be interpreted as a list of known side effects.
Whether these reports will have any influence on the uptake of GLP-1s remains to be seen.
