Brazilian health authorities are investigating 65 deaths potentially linked to complications from the use of weight loss medications, commonly known as “skinny pens,” over the past seven years. The investigation, initiated by the National Health Surveillance Agency (Anvisa), covers the period from December 2018 to December 2025 and does not include incidents reported in the current year. Alongside the reported deaths, Anvisa has recorded a total of 2,436 adverse event notifications associated with these medications, ranging from common side effects like nausea and diarrhea to more severe reactions described as “near-death experiences.”
The increasing use of these medications, often containing glucagon-like peptide-1 (GLP-1) receptor agonists, has prompted heightened scrutiny from regulators. These drugs, initially developed for the treatment of diabetes, have gained popularity for weight management due to their ability to mimic the GLP-1 hormone, which regulates blood sugar levels and promotes feelings of fullness. The investigation into potential adverse effects highlights the importance of careful monitoring and regulation of these increasingly popular drugs.
The Anvisa notifications involve four key substances: semaglutide (marketed as Ozempic and Wegovy), liraglutide (available in biosimilar versions from various laboratories), dulaglutide, and tirzepatide (currently sold exclusively as Mounjaro). However, the agency’s data doesn’t differentiate between legally obtained medications prescribed by a doctor and those acquired through unregulated channels, such as imports from Paraguay or compounded formulations.
Anvisa had previously disclosed investigations into six suspected deaths linked to pancreatitis – inflammation of the pancreas – associated with the use of these pens between 2020 and 2025. However, the latest data reveals the scope of potential complications is significantly larger when considering all reported deaths under investigation. Pancreatitis can disrupt digestion and blood sugar control, and is a serious potential side effect.
Adverse Events and Reported Cases
Even as most reported adverse events are mild and expected side effects like nausea, vomiting, and diarrhea, a small percentage – approximately 1% of the 2,436 notifications between 2023 and 2025 – involve more serious complications. These include pancreatitis, asthenia (persistent fatigue), and the aforementioned “near-death experiences,” with 71 such occurrences reported. Anvisa emphasizes that a single notification can detail multiple adverse events, leading to a higher overall count of reported outcomes.
Analysis of the data from the last three years, when all four substances were available in Brazil, shows that semaglutide (Ozempic/Wegovy) accounted for 69% of the reported adverse events. Liraglutide and tirzepatide (Mounjaro) each contributed 15% to the total.
Regulatory Response and Safety Concerns
Anvisa plays a crucial role in monitoring medication safety and updating guidelines based on new information. The agency has issued alerts regarding potential vision loss and risks associated with using these medications in patients undergoing sedation, in addition to the recent warning about an increased risk of pancreatitis. This latest alert followed an analysis of data from the UK’s Medicines and Healthcare products Regulatory Agency (MHRA), which identified an increase in pancreatitis cases among patients using these drugs. The MHRA reported 1,296 cases of pancreatitis between 2007 and 2025, with 19 suspected deaths. NeoFeed
Anvisa clarifies that reporting an adverse event does not automatically establish a causal link to the medication. “To determine if a real relationship exists, a complete clinical and scientific evaluation is necessary, considering various elements: the patient’s clinical condition, concurrent use of other medications, other possible explanations for the event, the quality and completeness of the information provided in the notification, and the origin and regularity of the medication used,” the agency stated. The agency stresses that the reported data should not be interpreted as proof that the medication causes the problem or is unsafe.
Agência Pública is currently conducting an in-depth investigation into the industries surrounding obesity, food, and pharmaceuticals, including the realities, risks, and interests behind weight loss pens. Their findings will be released in a podcast titled “A Última Bolacha” in March.
What to Expect Next
The ongoing investigation by Anvisa underscores the necessitate for continued vigilance regarding the safety of weight loss medications. As more data becomes available and further research is conducted, a clearer understanding of the potential risks and benefits of these drugs will emerge. Consumers and healthcare professionals should remain informed about the latest findings and adhere to recommended guidelines for safe and appropriate use. The agency’s commitment to monitoring and evaluating these medications will be crucial in protecting public health.
Have you or someone you know experienced adverse effects while using weight loss medications? Share your experiences in the comments below. Please also share this article with anyone who may be considering or currently using these drugs.
Disclaimer: This article provides informational content and should not be considered medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
