Weight loss and diabetes drugs from the GLP-1 family, including Ozempic, Wegovy and Mounjaro, have emerged as a breakthrough in the effective and safe treatment of obesity, which is defined globally as an epidemic. The drugs promote significant weight loss and improve diabetes control, and their use is expanding in Israel and worldwide.A new study, however, originating at Sheba Medical Center following the hospitalization of a patient with unusual findings, now raises an important question: In rare cases, could these medications be associated with a severe neurological complication, and is it preventable?
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Could weight loss drugs be linked to a severe neurological complication?
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The study began after a young woman was admitted to an Internal Medicine department at Sheba with alarming symptoms, including confusion, unsteady walking and visual impairment. The department’s medical team identified a suspicious clinical picture consistent with Wernicke’s encephalopathy, a rare, life-threatening neurological condition caused by severe vitamin B1 deficiency.
Further evaluation revealed that the patient had recently begun treatment with a GLP-1 weight loss medication, experienced rapid weight loss and suffered from frequent vomiting. Blood tests showed low vitamin B1 levels, with no other findings to explain her condition. After receiving intravenous vitamin B1, her condition improved markedly.
Following the case, Dr. Adam Goldman, an internal medicine specialist and Gastroenterology Fellow at Sheba Medical Center, led a large-scale study in collaboration with physicians from Sheba’s Internal Medicine department and Dr. Dana Lev to examine a possible association between GLP-1 medications and Wernicke’s encephalopathy.
Dr. Adam GoldmanPhoto: Sheba Medical Center
The researchers analyzed the FDA Adverse Event Reporting System (FAERS), which includes drug safety data, alongside a systematic review of medical literature. In total, 15 documented cases of Wernicke’s encephalopathy following GLP-1 use were identified: 8 occurred after treatment with semaglutide, marketed as Ozempic or Wegovy; 6 followed treatment with tirzepatide, marketed as Mounjaro; and 1 after treatment with liraglutide, marketed as Victoza.
In most cases, patients experienced vomiting, rapid weight loss or malnutrition following treatment. Another challenge was that many did not present with all the classic symptoms of Wernicke’s encephalopathy, complicating early diagnosis.
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Wernicke’s encephalopathy, a rare neurological disease
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The study also included contributions from the nutrition clinic staff at Sheba’s Gastroenterology Institute and an academic collaboration with Prof. Hertzel Gerstein of McMaster University in Canada, one of the world’s leading researchers in diabetes and metabolism.
Among 11 patients for whom follow-up data were available, 7 were left with permanent neurological damage. Importantly, the study does not prove causality and does not allow conclusions about how common the phenomenon is in the general population.
Dr. Goldman explained the health implications: “GLP-1 medications 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. However, the case we encountered highlights how important it is to be alert in situations involving vomiting, rapid weight loss or malnutrition. In such cases, vitamin B1 deficiency can develop quickly, and if identified in time, a severe neurological complication can be prevented with simple treatment.”
Dr. Dana LevPhoto: Sheba Medical Center
How well is Wernicke’s encephalopathy recognized in the medical community as a non-alcohol-related complication?
“The syndrome is characterized by a classic triad of confusion, eye movement issues, and poor coordination,” explains Dr. Goldman. “It is linked to vitamin B1, or thiamine, deficiency and for many years was identified primarily with alcoholism, which is how it was traditionally described in the medical literature,” he said.
Over the past 20 years, understanding of the syndrome has expanded, and it has also been linked to bariatric surgery, where thiamine deficiency may develop. “As a result, the issue has been incorporated into clinical guidelines in bariatric surgery. The common denominator is vomiting and significant weight loss accompanied by basic nutritional deficiencies.
“The same pathophysiological logic applies here. People with obesity may already have poor nutrition and deficiencies, followed by rapid weight loss and vomiting, making the mechanism similar,” he said.
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Sheba researchers recommend monitoring vitamin B1 levels in patients treated with GLP-1 medications
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Are there currently any formal international guidelines for nutritional or vitamin monitoring in patients taking these medications?
No. This is one of the study’s most surprising findings, said Dr. Goldman. “The issue is not regulated in the context of weight loss drugs, and very few studies have examined it. The existing literature is also extremely limited,” he added.
Therefore, our study points to a clear need for developing guidelines and for a basic recommendation to monitor vitamin B1 levels during treatment, particularly in patients experiencing significant weight loss or vomiting.
“It also raises the question of whether these situations are associated with additional nutritional deficiencies, including other vitamins.
Early diagnosis of vitamin B1 deficiency allows for simple treatment with oral or intravenous supplementation and may prevent a severe, sometimes irreversible, neurological complication.
GLP-1 medications are considered safe and effective for most patients and have revolutionized the treatment of obesity and diabetes. They have undergone extensive and rigorous safety studies prior to approval and are regarded as safe by international standards.
Still, the findings underscore the need for medical vigilance. The appearance of neurological symptoms such as confusion, dizziness, trouble walking or visual problems, particularly in patients experiencing vomiting and rapid weight loss, requires immediate medical evaluation.