A rare, serious brain condition has been identified in a small number of people taking GLP-1 weight loss and diabetes drugs, a new study revealed.
Some 15 cases of Wernicke encephalopathy were identified between 2023-2024 in an Israeli study’s review of the U.S. Food and Drug Administration’s adverse event reports and related literature.
Wernicke encephalopathy is a potentially life-threatening neurological disorder caused by a severe deficiency of vitamin B1 that can lead to permanent memory loss and an inability to form new memories.
Experts stressed that this condition is not common.
"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,” Karthik Achari, a Chicago-based clinician who was not involved in the study, 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.
Most of the 15 cases in the study were reported in people suffering gastrointestinal side effects from the drugs, such as vomiting and diarrhea, and loss of appetite.
Vitamin B1, which supports the nervous system and brain health, only comes from food and supplements.
“Most patients [13 of 15] reported gastrointestinal manifestations of either weight loss, vomiting, loss of appetite or malnutrition,” the researchers wrote.
Some 11 percent of U.S. adults - or around 30 million - now take GLP-1 drugs for weight loss, according to a Gallup poll conducted this summer.
The majority of the cases in the study occurred with GLP-1 drugs made with the active ingredient semaglutide, such as Ozempic and Wegovy, or tirzepatide GLP-1s, like in Zepbound.
"Patient safety is of utmost importance to Novo, and we take all reports about adverse events from the use of our medicines very seriously," Novo Nordisk, which makes Ozempic and Wegovy, told The Independent in an email.
The Independent has contacted Eli Lilly, which makes Zepbound, for comment.
The findings suggest that patients on the drugs who experience more intense gastrointestinal side effects may be at an increased risk for Wernicke encephalopathy.
However, the researchers noted that FDA reports cannot prove the GLP-1 medications caused the condition. More research is needed to do that and the scientists were clear that patients should not stop taking prescribed GLP-1 drugs based on the study alone.
Past research has also discovered possible links between a small number of GLP-1 drug users and the brain condition.
“We noticed that patients weren't just losing weight; they were also experiencing severe gastroparesis and persistent vomiting,” Dr. Manar Kadhem, from Egypt’s Mansoura University, wrote in the research published in April.
Immediate treatment is necessary to prevent the worst outcomes from Wernicke encephalopathy.
“Emergency treatment with thiamine is essential. It may relieve symptoms and prevent permanent damage to memory and other brain functions,” the Cleveland Clinic explains.
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