FORT WAYNE, Ind. (WOWO) — Popular GLP-1 medications used for weight loss and diabetes treatment have been linked in a new study to a rare but potentially life-threatening neurological condition caused by severe vitamin B1 deficiency.
Researchers identified 15 reported cases of Wernicke encephalopathy among people taking GLP-1 receptor agonists, according to a study published in the journal Clinical Nutrition.
The medications examined included semaglutide, sold under the brand names Ozempic and Wegovy, and tirzepatide, marketed as Mounjaro and Zepbound.
Wernicke encephalopathy occurs when the body becomes severely deficient in thiamine, also known as vitamin B1. The vitamin is essential for normal brain function.
The researchers found that many of the patients had experienced significant gastrointestinal or nutritional problems, including vomiting, appetite loss, rapid weight loss and malnutrition.
Those symptoms are important because GLP-1 medications can substantially reduce appetite and may cause nausea and vomiting in some patients. If someone is eating very little for an extended period while also losing nutrients through vomiting, a serious nutritional deficiency can develop.
The study does not, however, establish that GLP-1 medications directly caused Wernicke encephalopathy.
Researchers identified the cases using reports from the FDA’s Adverse Event Reporting System, previously published medical literature and records from their own medical center. Because the analysis relies largely on reported cases, it cannot establish how frequently the condition occurs among the millions of people taking GLP-1 drugs or prove a cause-and-effect relationship.
Karthik Achari, a Chicago-based clinician who was not involved in the research, said the number of reported cases needs to be considered in context.
“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,” Achari told Fox News Digital. “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,” he said.
Vitamin B1 deficiency can affect the nervous system and, in severe cases, lead to confusion, problems with balance or walking and changes in vision. Without treatment, Wernicke encephalopathy can cause permanent neurological damage and can be fatal.
Achari said the appetite-suppressing effects of GLP-1 medications can make adequate nutrition particularly important.
“The drug shrinks your appetite. It doesn’t shrink your body’s requirements,” he said.
He noted that people taking these medications still need adequate protein, vitamins, fluids and other nutrients even when they feel less hungry.
People who experience persistent nausea or vomiting may warrant particular attention, especially if they are losing weight rapidly while eating very little.
Achari also identified people with a history of bariatric surgery and those who consume alcohol heavily as potentially higher-risk groups for vitamin B1 deficiency.
Nutritionist Erin Palinski-Wade told Fox News Digital that maintaining adequate nutrition and hydration should be considered part of taking GLP-1 medications safely.
“GLP-1 medications can dramatically reduce appetite, but that also means people may unintentionally under-eat the very things their bodies need most, especially protein, fiber and fluids,” she said.
Persistent vomiting or diarrhea can create additional concerns because of fluid loss and the potential for dehydration and kidney problems.
Palinski-Wade advised patients not to automatically dismiss severe or prolonged symptoms as routine medication side effects.
“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 said additional studies are needed to better understand whether there is a relationship between GLP-1 medications, nutritional deficiencies and Wernicke encephalopathy.
The findings do not mean patients should stop taking prescribed GLP-1 medications on their own.
Anyone taking a GLP-1 drug who develops persistent vomiting, significant difficulty eating or drinking, unusual confusion, problems with balance or walking, or changes in vision should contact a health care professional promptly.
Patients should also discuss significant side effects or rapid weight loss with the clinician who prescribed the medication.
The study’s findings serve as a reminder that reduced appetite can have nutritional consequences. While Wernicke encephalopathy appears to be rare, experts say maintaining adequate food and fluid intake and addressing persistent gastrointestinal symptoms are important considerations for people taking GLP-1 medications.
