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Using GLP-1s

Pharmacovigilance

The ongoing monitoring of a medication's safety after it reaches the market. It is the discipline behind the FAERS (now AEMS) signals and disproportionality studies that generate many GLP-1 side-effect headlines.

By the glp1.how editorial teamReviewed

Pharmacovigilance is the system for watching a medication's safety after it is approved. Clinical trials enroll a few thousand carefully selected people for a limited time, so rare, delayed, or population-specific side effects only surface once millions of people are taking a drug. Regulators (the FDA, the European Medicines Agency), manufacturers, and academic researchers collect adverse-event reports, compare them against expected rates, and decide whether a label change, warning, or further study is needed.

Many GLP-1 safety questions (suicidal ideation, gastroparesis, hair loss, a rare eye condition called NAION) have been raised or investigated this way. One common tool is the "reporting odds ratio," which compares how often a side effect is reported with one drug versus all other drugs in the database. A high ratio flags a signal worth investigating, but it does not by itself show the drug caused the effect, because reporting is uneven. In the FDA's database (called FAERS until March 2026, when it became part of the FDA Adverse Event Monitoring System, or AEMS), reporting is voluntary for patients and clinicians, while manufacturers are required to forward the reports they receive (FDA AEMS dashboard FAQ (external link); FDA, March 2026 (external link)). Follow-up usually means large cohort studies or trial re-analyses. That is how the European Medicines Agency's safety committee concluded in April 2024 that the available evidence did not support a causal link between GLP-1s and suicidal thoughts (EMA PRAC, April 2024 (external link)). See mood changes and anhedonia on a GLP-1.

pharmacovigilancesafetyfaersside-effects

Revision history

Updated 2 times since Sep 2, 2026 · show changes
  1. v3

    Summary rewritten; Body revised

  2. v2

    Summary rewritten; Body revised

  3. v1

    Change tracking began

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Related terms

  • Gastroparesis · A diagnosis of abnormally delayed stomach emptying with persistent symptoms. GLP-1 medications cause mild, temporary slowing in many people, which is not the same thing, but the Wegovy label says it is not recommended in severe gastroparesis.
  • GLP-1 · A gut hormone (glucagon-like peptide-1) that stimulates insulin release, slows digestion, and reduces appetite; the target of drugs like semaglutide and liraglutide.
  • FAERS (FDA Adverse Event Reporting System, now AEMS) · The FDA's database of voluntary side-effect reports from patients, clinicians, and manufacturers, used to detect safety signals after a drug is on the market. In March 2026 it became part of the FDA Adverse Event Monitoring System (AEMS).

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