Analysis of FDA reports found disproportionate semaglutide signals for heavy bleeding, clots, infrequent periods and cycles without ovulation. Tirzepatide also showed signals for bleeding between periods and clots; the reports cannot prove the drugs caused these changes.
Researchers analyzed FAERS reports for female patients ages 12–55 through March 2026, using disproportionality and Bayesian methods to detect unusual reporting patterns. Liraglutide showed no significant menstrual-event signals, and FAERS has no reliable denominator to calculate how common such events are among users.
Researchers could not separate a medication effect from weight loss, metabolic changes or conditions such as obesity, PCOS and diabetes, which can also affect cycles. The anovulation signal does not establish that semaglutide routinely suppresses ovulation or reduces fertility; prospective studies are needed to clarify whether the patterns represent drug effects.
