Researchers have identified a small number of cases of Wernicke encephalopathy—a serious brain disorder caused by severe vitamin B1 deficiency—in patients taking popular GLP‑1 receptor agonists. The findings, published in Clinical Nutrition, were based on 15 reports gathered from the FDA’s Adverse Event Reporting System, medical literature and the authors’ own medical center.
What the study found
All 15 cases involved users of GLP‑1 medications, most commonly semaglutide (marketed as Ozempic and Wegovy) or tirzepatide (sold as Mounjaro and Zepbound). Patients typically experienced gastrointestinal symptoms such as vomiting, loss of appetite, rapid weight loss or overall malnutrition, which can deplete the body’s vitamin B1 stores.
Wernicke encephalopathy can cause confusion, difficulty walking, balance problems and vision changes. If untreated, it may lead to permanent neurological damage or death. The researchers emphasized that while the association is concerning, the study cannot prove the drugs directly caused the condition.
Expert perspective
Karthik Achari, a Chicago‑based clinician and founder of PepMD, cautioned that the 15 cases represent a very small fraction of the millions of people using GLP‑1 therapies. “That’s rare,” he said, “but it’s real and serious, and the mechanism makes sense.” He explained that GLP‑1 drugs suppress appetite, which can inadvertently reduce intake of essential nutrients, including vitamin B1.
“The drug shrinks your appetite. It doesn’t shrink your body’s requirements,” Achari added. “You can now eat very little without feeling it, which is the point of the medication, but your need for protein, vitamins, and fluids didn’t go anywhere.”
Erin Palinski‑Wade, a nutritionist from New Jersey, echoed the need for vigilant nutrition. She warned that persistent 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.”
Who may be at higher risk?
Achari noted that individuals who experience ongoing nausea and vomiting, lose weight rapidly while eating very little, have a history of bariatric surgery, or consume alcohol heavily may face a heightened risk of vitamin B1 deficiency.
Patients experiencing these symptoms for more than 24 hours should seek medical guidance promptly.
What the medical community recommends
The study’s authors called for additional research to better understand the link and to develop guidelines for monitoring vitamin B1 levels in patients on GLP‑1 therapy. In the meantime, they advised clinicians to counsel patients on maintaining adequate nutrition and, when appropriate, consider supplementation.
Fox News Digital reached out to the manufacturers—Novo Nordisk and Eli Lilly—and to the study’s researchers for comment; none responded at the time of publication.
Bottom line for patients
While the risk of Wernicke encephalopathy appears extremely low relative to the millions benefiting from GLP‑1 medications, the condition is serious. Patients should remain aware of any persistent gastrointestinal symptoms and discuss nutritional strategies with their healthcare providers to ensure they meet their body’s vitamin and protein needs while using these drugs.
Original reporting: Fox News (HLL/CB) — read the source article.
