Semaglutide Linked to Rare Brain Illness

TOPLINE

A systematic review synthesized findings from six case reports that linked semaglutide use for obesity to Wernicke encephalopathy in mostly middle-aged patients with multiple comorbidities. In each case, gastrointestinal symptoms preceded neurologic decline, which was commonly marked by mental status changes and oculomotor abnormalities. Outcomes were often poor, with four patients developing persistent cognitive deficits consistent with Korsakoff syndrome and one patient dying.

METHODOLOGY

• As GLP-1s are increasingly used for obesity, their appetite-suppressing and persistent gastrointestinal effects can increase the risk for nutritional deficiencies, including thiamine, which can lead to Wernicke encephalopathy — a rare but potentially fatal disorder that can cause irreversible cognitive impairment if not promptly recognized and treated.
• Researchers systematically reviewed medical literature through February 10, 2026, to synthesize case-based evidence on Wernicke encephalopathy following semaglutide treatment for obesity.
• Case reports were included when semaglutide (Ozempic or Wegovy) was prescribed for obesity and the presentation was consistent with Wernicke encephalopathy. Diagnosis was based on the Caine operational criteria; the presence of the classic triad of confusion, ataxia, and ocular abnormalities; autopsy confirmation; or documented clinical response to parenteral thiamine.
• Extracted data included patient demographics, the indication for semaglutide, treatment duration and dosing, presenting signs of Wernicke encephalopathy, neuroimaging findings, the thiamine treatment regimen, and clinical outcomes, with suboptimal treatment defined as < 500 mg of parenteral thiamine as the initial dose.

TAKEAWAY

• Across six patients with Wernicke encephalopathy (four women and two men; mean age, 47.2 years), semaglutide was used for an average of 4.9 months before the condition developed.
• Most patients (five of six) had comorbid health problems, including mental health issues and chronic illnesses.
• Before the onset of Wernicke encephalopathy, appetite loss was reported in five of six patients, weakness in four of six patients, vomiting in three of six patients, and constipation in two of five patients. On presentation, mental status changes were the most frequently observed finding (five of six patients), with nystagmus of the eyes also observed in five of six patients and ataxic gait disturbance in four of six patients.
• All five patients who underwent MRI showed classic signs of Wernicke encephalopathy, and on follow-up, one patient died, one patient recovered fully, and four patients had persistent memory impairment consistent with chronic Korsakoff syndrome (one of whom also developed chronic loss of leg function).

IN PRACTICE

“As the use of GLP-1 RAs [GLP-1 receptor agonists] continues to expand, clinicians should maintain a high index of suspicion for WE [Wernicke encephalopathy] in symptomatic patients and initiate prompt parenteral thiamine therapy when indicated,” the authors of the study wrote.