Study links GLP-1 weight-loss drugs to rare cases of Wernicke encephalopathy

A review of FDA adverse-event reports, published literature and data from a medical center found 15 instances of Wernicke encephalopathy, a severe neurological disorder caused by vitamin B1 deficiency, among users of GLP-1 receptor agonists such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). The cases were associated with gastrointestinal symptoms, rapid weight loss, vomiting, loss of appetite or malnutrition, which can reduce thiamine intake.

The authors cautioned that the analysis cannot establish a causal relationship between the drugs and the disorder, but the incidence appeared higher than among users of other medications. Vitamin B1 deficiency can lead to confusion, gait disturbances, vision changes and, if untreated, permanent neurological damage or death.

"Researchers went through adverse event reports and the medical literature and found a small number of cases, 15, of Wernicke encephalopathy in people taking GLP-1 drugs," said Karthik Achari, a clinician not involved in the study. "That's out of millions of people on these medications. So this is rare. But it's real, it's serious, and the mechanism makes sense."

Achari noted that GLP-1 drugs suppress appetite and can cause nausea or vomiting, potentially leading to insufficient intake of thiamine, protein, and fluids. He added that individuals with persistent nausea, rapid weight loss, a history of bariatric surgery or heavy alcohol use may be at higher risk.

Nutritionist Erin Palinski-Wade emphasized the importance of adequate nutrition and hydration while on GLP-1 therapy, warning that ongoing vomiting or diarrhea can increase the risk of dehydration and kidney problems. "Don't assume every side effect is just part of being on a GLP-1," she said. "Severe or persistent symptoms deserve attention."

The researchers called for further investigation and advised patients not to discontinue prescribed GLP-1 medications without medical guidance.