Weight loss medications, including Mounjaro and Wegovy, have been associated with at least 216 deaths in the United Kingdom, with severe or fatal reactions numbering around 18,000 since 2010, according to an analysis of official drug safety data. The figures show a 300 percent increase in annual fatalities linked to these drugs between 2024 and 2025, rising from 22 to 94.
Tirzepatide, the active ingredient in Mounjaro, is linked to the majority of these cases. Since its licensing in 2024, 120 deaths have been reported to the UK's Medicines and Healthcare products Regulatory Agency (MHRA) in connection with tirzepatide. Semaglutide, marketed as Wegovy and Ozempic, is linked to 59 fatalities, and liraglutide (Saxenda) to 37.
Of the 18,000 serious or fatal adverse reactions recorded, 11,500 specifically concern tirzepatide. Close to 8,000 of these Mounjaro-related reports involved women. The most frequently reported issues involve gastrointestinal conditions such as pancreatitis and gastroparesis, or stomach paralysis.
These findings emerged shortly after an inquest heard about the death of Caroline Savage, a 73-year-old grandmother who died from faecal peritonitis after increasing her Mounjaro dose. This condition occurs when bacteria leak into the abdomen through a perforation in the bowel, often leading to life-threatening sepsis.
Experts suggest that these GLP-1 agonist medications, which mimic appetite-suppressing hormones, can slow gut function. This can lead to a buildup of waste products, increasing pressure on the bowel lining and potentially causing perforation, especially in individuals with underlying conditions. Pharmaceutical expert Penny Ward of King's College London noted that while nausea and vomiting are common side effects, severe, sudden abdominal pain warrants immediate investigation as it could indicate a more serious complication.
The MHRA collects data through its Yellow Card scheme, where suspected adverse drug reactions are reported by the public, healthcare professionals, and pharmaceutical industry workers. Officials emphasize that these reports indicate a suspected link and do not prove causation, as other health factors may be involved. The agency also noted that reporting volumes can be influenced by increased drug usage, heightened awareness of potential side effects, and other factors.
Novo Nordisk, the manufacturer of Wegovy, Ozempic, and Saxenda, stated that side effects can vary and recommended patients report any experienced issues to their healthcare provider and the MHRA. Eli Lilly, the maker of Mounjaro and Zepbound, affirmed that patient safety is a top priority and that they actively monitor their medicines. Both companies highlighted that regulatory agencies conduct thorough benefit-risk assessments and that Mounjaro should only be used as prescribed by a healthcare professional. NHS England declined to provide figures on official hospitalizations related to GLP-1 users.