Comparative adverse-event reporting patterns of semaglutide and tirzepatide: a disproportionality analysis of FAERS

Semaglutide and tirzepatide are widely used for type 2 diabetes and obesity, but comparative post-marketing safety data remain limited.

To compare adverse-event reporting patterns for semaglutide and tirzepatide in the FDA Adverse Event Reporting System (FAERS), focusing on gastrointestinal, renal and ocular events, alopecia, serious outcomes, mortality, and reporting chronology.

This retrospective pharmacovigilance study analyzed FAERS reports submitted from January 2022 through June 2026. After deduplication, 215,337 unique reports remained; predefined exposure criteria identified 60,423 semaglutide-only reports, 143,126 tirzepatide-only reports, and 853 reports listing both drugs without additional suspect active ingredients. Disproportionality was assessed using reporting odds ratios (RORs) with 95% confidence intervals. Multivariable logistic regression, false discovery rate adjustment, and reporting-latency analyses were also performed.

Semaglutide showed higher reporting odds than tirzepatide for impaired gastric emptying (ROR 6.39), intestinal obstruction/ileus (ROR 4.56), acute kidney injury (ROR 2.51), pancreatitis (ROR 2.18), vomiting (ROR 2.11), and optic ischaemic neuropathy (ROR 15.77). Alopecia was relatively more frequently reported with tirzepatide (ROR 0.74). Semaglutide reports had higher adjusted reporting odds of hospitalization (aOR 2.80) and death (aOR 1.21). In an exploratory analysis restricted to male reports, erectile dysfunction was reported in 92 of 16,673 semaglutide reports and 46 of 27,321 tirzepatide reports (ROR 3.29, 95% CI 2.31-4.69; q < 0.001).

Semaglutide and tirzepatide exhibited distinct post-marketing reporting patterns. The erectile-dysfunction finding was exploratory and hypothesis-generating. All findings reflect spontaneous reporting rather than comparative clinical risk or causality and require confirmation in population-based studies.