GLP-1 Drugs Work. The Side-Effect List Keeps Growing.
From nail detachment to vision lawsuits, the most widely used weight-loss drugs in history are accumulating an unexpected portfolio of risks.
By The energy-climate Desk
Eleven percent of Americans are now taking a GLP-1 drug for weight loss—up from 3% in 2024, according to a recent Gallup poll—and researchers are still cataloguing what those drugs actually do to the body. [1]
The headline benefit is striking: overweight and diabetic patients who take GLP-1s show a biological age around two to three years younger than similar individuals on a placebo, according to findings from Eli Lilly and Novo Nordisk presented at an aging meeting in Boston. [1]
The downsides are less tidy. Gastrointestinal effects—nausea, vomiting, diarrhea, constipation—affect more than 1 in 10 patients and can, if unmanaged, lead to severe dehydration and hospitalisation. [1][2] The UK's MHRA had received 7228 Yellow Card reports of the common gastrointestinal reactions of nausea, vomiting and diarrhoea in association with GLP-1RAs indicated for weight management as of 28 October 2024, with 68 of those reports indicating hospitalisation of the individual. [2]
Further up the risk register: pancreatitis, gallstone disease, and a contested link to sudden vision loss. Dozens of people are suing Novo Nordisk and Eli Lilly after developing a condition that can lead to sudden vision loss, though both companies dispute the claims and research into the link is mixed. [1]
Stranger findings are emerging at the body's periphery. A study drawing on electronic health data from 67 US health-care organizations found GLP-1 use associated with an increased risk of hair loss. [1] A separate conference presentation reported that 66% of GLP-1 users reported at least one nail disorder—in some cases involving nail detachment. [1]
The picture that emerges is one of a drug class outrunning its own evidence base—benefits multiplying alongside questions that trails of real-world data are only beginning to answer.
Between 2019 and 2026, GLP-1 prescriptions for eight- to 11-year-old children with obesity in the US rose 310-fold—making the pediatric side-effect gap, where data is thin, the next frontier regulators will have to navigate. [1]