An analysis of nearly 29,000 adverse event reports found 19 distinct neurological side effects associated with GLP-1 drugs, with nearly half occurring within the first month of treatment.
45.28%of neurological adverse events occurred within the first 30 days of starting a GLP-1 drug
What the researchers found
Across six GLP-1 receptor agonists (exenatide, liraglutide, lixisenatide, dulaglutide, semaglutide, and tirzepatide), 19 distinct neurological adverse event signals were identified from 28,953 reports in the FAERS database spanning 2005–2024.
The most notable signals included dizziness, tremor, dysgeusia (taste distortion), lethargy, taste disorder, presyncope (near-fainting), parosmia (smell distortion), allodynia (pain from normally non-painful touch), and hypoglycemic unconsciousness.
Time-to-onset analysis showed a median latency of 32 days (IQR 7–122 days), with 45.28% of neurological events occurring within the first 30 days of treatment initiation. These signals were confirmed across multiple statistical methods including reporting odds ratios, proportional reporting ratios, information components, and empirical Bayes geometric means.
Why it matters
With tens of millions of people now taking GLP-1 drugs for weight loss and diabetes, understanding their neurological safety profile is critical. This is the largest pharmacovigilance study to systematically catalog neurological side effects across all six approved GLP-1 receptor agonists, giving doctors a clearer picture of what to watch for — especially in the crucial first month of treatment.
How the study worked
The researchers analyzed the FDA Adverse Event Reporting System (FAERS) database from Q2 2005 through Q3 2024. They used a statistical approach called disproportionality analysis, which compares how often a side effect is reported with a specific drug versus all other drugs. They applied four different statistical methods to confirm their findings, and also analyzed how quickly after starting the drug each neurological event appeared.
What this study cannot tell us
The FAERS database relies on voluntary reporting, which means side effects may be underreported or overreported. The data can't prove that GLP-1 drugs actually caused these neurological events — only that they were reported together. Confounding factors like other medications, underlying conditions, and the demographics of who reports aren't fully controlled for. The analysis also can't determine how common these events actually are in the overall population taking these drugs.
How to read the evidence
This is a pharmacovigilance database study using voluntary adverse event reports, which can identify safety signals but cannot establish causation. It sits below randomized controlled trials and prospective cohort studies in the evidence hierarchy.
When this study was published
Published in 2025, this study uses the most recent FAERS data available through Q3 2024, making it highly current and relevant to the ongoing GLP-1 safety discussion.
The bigger picture
As GLP-1 drugs become some of the most prescribed medications worldwide, post-market safety surveillance becomes increasingly important. Most clinical trials focus on metabolic and gastrointestinal effects, so neurological side effects may be underrecognized. This study adds to a growing body of pharmacovigilance research suggesting that GLP-1 receptor agonists have effects on the nervous system that warrant closer study in prospective clinical trials.
Questions still open
- Do specific GLP-1 drugs carry higher risk for particular neurological side effects than others?
- What biological mechanisms might explain how GLP-1 receptor activation in the brain leads to neurological adverse events?
- Would prospective clinical trials designed to monitor neurological outcomes confirm these pharmacovigilance signals?
Common questions
What neurological side effects were found with GLP-1 drugs?
How soon after starting a GLP-1 drug do neurological side effects typically appear?
Read the original research
Pharmacovigilance analysis of neurological adverse events associated with GLP-1 receptor agonists based on the FDA Adverse Event Reporting System.
Scientific reports, 15(1), 18063
Citation
Chen, He; Liu, Sixing; Gao, Shuai; Shi, Hangyu; Yan, Yan; Xu, Yixing; Fang, Jiufei; Wang, Weiming; Chen, Huan; Liu, Zhishun. (2025). Pharmacovigilance analysis of neurological adverse events associated with GLP-1 receptor agonists based on the FDA Adverse Event Reporting System.. Scientific reports, 15(1), 18063. https://doi.org/10.1038/s41598-025-01206-9