GLP-1 Drugs Under Scrutiny for Pancreatitis Risk and Athletic Use

The United Kingdom and Brazil have issued warnings about a possible link between GLP-1 weight-loss drugs and pancreatic inflammation, though the connection remains unclear. The risk of pancreatitis is already listed in information leaflets provided to people taking the drugs, but a large increase in the number of pancreatitis reports in recent years, including severe cases and deaths, prompted the UK Medicines and Healthcare products Regulatory Agency (MHRA) to strengthen its warning.

The 19 deaths recorded in the United Kingdom were reported between 2007 and October 2025. In the same period, nearly 1,300 reports of pancreatitis associated with GLP-1 drugs were reported to health officials. The six deaths in Brazil were reported from 2020 to December 2025, as were 145 cases of pancreatitis in people taking GLP-1 medications. Widespread use of the drugs to treat obesity began in 2021.

Considering the number of people taking these drugs—in Great Britain alone, an estimated 1.6 million adults used GLP-1 medications between early 2024 and early 2025—the risk of developing these side effects is very small. By comparison, thousands of people are hospitalized with pancreatitis in Britain every year.

It's very challenging to determine whether the cases of pancreatitis were directly caused by the drugs because many people on these medications already have an increased risk for pancreatitis to begin with. Furthermore, anyone can report drug side effects to the UK and Brazilian databases that were the source of the case numbers.

Data about the risk of pancreatitis with GLP-1 use has been very heterogeneous. A 2025 meta-analysis of 62 randomized controlled clinical trials of several GLP-1 drugs found that people on these medications had a slightly increased risk of pancreatitis compared with those on a placebo. But other analyses found no such association.

In an effort to provide an answer to patients who were hesitant about taking the drugs because of possible side effects, researchers compared the risk of pancreatitis between two groups, each comprising nearly 82,000 people with type 2 diabetes. The groups had similar risk factors for pancreatitis, but people in one group were taking GLP-1 drugs and people in the other group were not. The researchers found no difference in pancreatitis rates between the two.

GLP-1 receptor agonists—sold under brand names like Ozempic and Mounjaro—were initially developed to treat diabetes. Scientists are now exploring the benefits of using the drugs for a host of other chronic diseases—many with few treatment options—such as heart failure, chronic liver disease, obstructive sleep apnea, and even substance use disorders.

Instead of addressing biomarkers linked to certain disease outcomes, these drugs influence the central cardio-kidney metabolic process. This overarching approach has made GLP-1 drugs the most effective and tolerable choice for most patients treating diabetes and obesity.

In a recent study, researchers found that GLP-1s were highly effective for patients with heart failure with preserved ejection fraction, in which the heart's muscle becomes so stiff that the ventricle holds less blood than usual; the GLP-1s showed a 40% relative risk reduction compared to older diabetes medication.

GLP-1 drugs were found to reduce the risk of major adverse cardiovascular events like cardiovascular death, nonfatal myocardial infarction, nonfatal stroke. And this has been shown over and over with different GLP-1s within the class.

The World Anti-Doping Agency (WADA) has included GLP-1 RAs in its 2026 monitoring list. This does not mean that athletes are banned from using these medications but rather that WADA is moving toward monitoring usage that suggests misuse or unintended performance consequences. For a drug or method to be included on the prohibited list, it must meet at least 2 of the following 3 criteria: performance enhancement, health risk to the athlete, or violation of the "spirit of sport."

GLP-1 RAs stimulate satiety and decrease energy intake via neuroendocrine pathways that inhibit appetite and delay gastric emptying. Although these properties are beneficial in the treatment of diabetes and obesity, they also influence nutritional and energy intake in athletes, whose metabolic rate is exceptionally high. Among the most important concerns is unintentional loss of lean muscle mass. Data from exercise and sports studies have shown that GLP-1 RAs decrease overall body weight while simultaneously decreasing lean mass, which includes skeletal muscle tissue essential for power, endurance, and recovery.

Physicians with expertise in sports medicine have highlighted prevalent misconceptions about GLP-1 agents among athletes. Taking a GLP-1 "does burn fat, but it also will burn muscle," emphasizing the physiological trade-offs that may detract from athletic capacity. Athletes can consequently experience diminished speed, endurance, and explosiveness—key determinants of peak performance. Some athletes mistakenly believe GLP-1 RAs "can help them increase their insulin, and by that measure, increase their muscle mass," but "that's not the case at all."

Currently, there is no convincing evidence of a performance-enhancing effect of GLP-1 RAs in healthy, non-diabetic individuals, while adverse effects such as decreased energy intake, fueling practices, and loss of lean mass could potentially impair performance.