WASHINGTON, Sept. 14 (DC Times Online) — People taking popular GLP-1 medicines such as Wegovy, Ozempic, Zepbound and Mounjaro are not being told to stop their prescriptions because of a small set of reports involving a rare brain disorder. But experts say prolonged nausea, vomiting, appetite loss or rapid weight loss can make it harder to get enough nutrients, including vitamin B1.
The condition, called Wernicke encephalopathy, can cause confusion, trouble walking, abnormal eye movements and vision changes. Medical experts quoted in reports said untreated cases can lead to lasting neurological damage or death.
The reports do not establish that GLP-1 medicines caused the disorder, and they do not show the overall risk for people who take the drugs.
What did the reported analysis find?
Researchers reportedly identified 15 cases of Wernicke encephalopathy among 195,979 adverse-event cases examined in an analysis published in Clinical Nutrition. The analysis used reports from the U.S. Food and Drug Administration’s Adverse Event Reporting System, published medical literature and records from the researchers’ own medical center.
The cases were reported during 2023 and 2024, according to accounts of the analysis. Most involved semaglutide, the active ingredient in Ozempic, Wegovy and Rybelsus, or tirzepatide, the active ingredient in Mounjaro and Zepbound. One reported case involved liraglutide, sold as Victoza.
The researchers said Wernicke encephalopathy appeared disproportionately among people taking GLP-1 medicines compared with other drugs. However, the available reports do not provide a population-wide risk estimate, a confirmed relative-risk figure or enough information to determine whether the medications caused the condition.
How could nutrition be involved?
Wernicke encephalopathy develops when the body has a severe shortage of thiamine, also known as vitamin B1. Thiamine helps the body process energy and supports the nervous system.
The proposed connection to GLP-1 medicines involves their effects on eating and digestion. These drugs can reduce appetite and may cause nausea or vomiting. If a person eats very little or cannot keep food down for an extended period, that person may not get enough thiamine or other nutrients.
Achari, an expert quoted in reports about the analysis, said: “The drug shrinks your appetite. It doesn’t shrink your body’s requirements.”
That explanation is a proposed mechanism, not proof that the drugs directly cause Wernicke encephalopathy. The available case reports also cannot show how often people taking GLP-1 medicines develop the condition.
Which symptoms are associated with the disorder?
Reported symptoms include confusion, problems with balance or walking, unusual eye movements and changes in vision. Nausea, vomiting, appetite loss, rapid weight loss and malnutrition were also commonly described in the reported cases.
Experts quoted in the coverage identified persistent nausea or vomiting, rapid weight loss while eating very little, previous bariatric surgery and heavy alcohol use as circumstances that may increase concern about thiamine deficiency. The underlying reports do not provide complete details for all 15 cases, including each person’s medical history, dose or treatment duration.
Because the early symptoms can overlap with other medical problems, the case reports alone cannot determine whether a symptom in a person taking a GLP-1 drug is caused by the medicine, nutritional deficiency or another condition.
What does this mean for people taking these medicines?
Experts quoted in the reports said patients should not stop prescribed GLP-1 medicines solely because of the findings. They called for additional research and clinical vigilance, particularly when gastrointestinal symptoms persist or a person is losing weight rapidly while eating very little.
Dr. Goldman said GLP-1 medicines “are among the most effective and important tools we currently have for treating obesity and diabetes, and the vast majority of patients take them safely.”
A separate review described six published case reports involving people treated with semaglutide for obesity. The review reported four women and two men, an average age of 47, and symptoms beginning after an average of 4.9 months of treatment. It described one death, four cases of lasting memory impairment and one full recovery.
That six-case review is separate from the 15-case analysis. The available information does not show whether any cases appeared in both groups.
Why the evidence is limited
Adverse-event reporting systems collect suspected side effects, but a report does not prove that a medicine caused the event. Such systems can include incomplete information, duplicate reports and cases involving other illnesses, medicines or risk factors.
The reported 15 cases are therefore a signal for further study, not a measure of the chance that an individual patient will develop Wernicke encephalopathy. The available material does not include the number of people taking the drugs, the number of people exposed to each medicine or a comparison group detailed enough to calculate an absolute risk.
For now, the reported findings point to a nutritional concern that clinicians may consider when patients using GLP-1 medicines have ongoing vomiting, severe appetite loss or rapid weight loss. They do not show that the medicines pose a broad or confirmed risk of this rare neurological disorder.
