Popular GLP-1 weight-loss drugs linked to potentially deadly brain disorder

Researchers are warning about a rare but potentially life-threatening brain condition that may be linked to popular GLP-1 weight-loss medications.

A new study, published in Clinical Nutrition, identified 15 reported cases of Wernicke encephalopathy, a neurological disorder caused by severe vitamin B1 deficiency, in people taking GLP-1 receptor agonists.

Most of the reported cases involved semaglutide, sold under the brand names Ozempic and Wegovy, or tirzepatide, sold as Mounjaro and Zepbound.

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Researchers found 15 cases through the FDA's Adverse Event Reporting System (FAERS), published medical literature and their own medical center.

Most patients reported gastrointestinal symptoms or nutritional issues, including weight loss, vomiting, loss of appetite or malnutrition, the study noted.

Reports of the disorder appeared more often among people taking GLP-1 medications than among those taking other drugs, the researchers found. They emphasized, however, that the study cannot prove the medications caused the condition.

Vitamin B1 plays an important role in brain function, the researchers said. Severe deficiencies can cause confusion, trouble walking, balance problems and vision changes. If left untreated, the condition can lead to permanent neurological damage or death.

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Karthik Achari, a Chicago-based clinician and founder of PepMD who was not involved in the study, said the findings should be viewed in perspective.

"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 added.

GLP-1 medications can reduce appetite while also causing nausea and vomiting, making it easier for some people to become deficient in vitamin B1, Achari said.

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"The drug shrinks your appetite. It doesn't shrink your body's requirements," he said. "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."

People with persistent nausea and vomiting, those losing weight very quickly while eating little, people with a history of bariatric surgery and those who use alcohol heavily may face a higher risk, Achari said.

Erin Palinski-Wade, a New Jersey-based nutritionist and author of "The Sleepdemic Solution," said proper nutrition and hydration should be considered part of treatment while taking GLP-1 medications.

"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 told Fox News Digital.

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Palinski-Wade said ongoing vomiting or diarrhea can increase the risk of dehydration and kidney problems. She urged patients to seek medical guidance if those symptoms continue for roughly 24 hours.

"Don't assume every side effect is just part of being on a GLP-1," Palinski-Wade said. "Severe or persistent symptoms deserve attention."

The researchers acknowledged that the study relied largely on reports submitted to the FDA and cannot prove GLP-1 medications caused the condition. They called for additional research, and experts said patients should not stop taking prescribed GLP-1 medications based on these findings alone.

Fox News Digital reached out to Novo Nordisk, Eli Lilly and the researchers for comment.