It looks like another health problem has popped up with some of the weight loss drugs so many women of reproductive age are now taking. This time menstrual related events, including heavy menstrual bleeding, blood clots, and frequency of menstrual bleeding.
Researchers looked at data in the FDA Adverse Event Reporting System for 3 weight loss drugs (Semaglutide, Tirzepatide, and Liraglutide), which are glucagon-like peptide-1 receptor agonists. They found that females aged 12 to 55 years (reproductive age) reported problems with 2 of the weight-loss drugs. Semaglutide had the most adverse reports: heavy menstrual bleeding, intermenstrual bleeding, menstrual clots, infrequent menstrual periods (oligomenorrhea), and cycles without ovulation (anovulatory cycles). Tirzepatide had reports of intermenstrual bleeding and menstrual clots, and Liraglutide had by far the fewest adverse reports ("produced no significant signals").
From Medscape: Menstrual Clots and Heavy Bleeding Linked to Popular Weight-Loss Drugs
GLP-1 receptor agonists (RAs), particularly semaglutide, are associated with disproportionate reporting of menstrual adverse events including heavy bleeding, intermenstrual bleeding, and menstrual clots in reproductive-aged female patients. Tirzepatide showed signals for intermenstrual bleeding and menstrual clots.
METHODOLOGY
- Researchers performed a disproportionality and Bayesian analysis using the FDA Adverse Event Reporting System (FAERS) database, collecting reports from database inception through March 2026, totaling 14,104,743 reports.
- Analysis was restricted to female patients aged 12-55 years, with total drug-associated reports numbering 4024 for liraglutide, 27,469 for tirzepatide, and 6060 for semaglutide.
- Investigators queried menstrual adverse events using Medical Dictionary for Regulatory Activities terminology, comparing GLP-1 RAs (semaglutide, liraglutide, and tirzepatide) against all other drugs in the FAERS database as the reference group.
- Two complementary statistical approaches were used: frequentist analysis calculating reporting odds ratio (ROR) with signals defined as the lower bound of the 95% CI for ROR exceeding 1, and Bayesian analysis generating a posterior ROR distribution with 95% credible intervals using 50,000 simulated samples.
- The study was conducted by researchers from the Department of Medicine at the University of British Columbia and Epilytics using publicly accessible pharmacovigilance data from physicians, patients, caregivers, and manufacturers.
TAKEAWAY
- Semaglutide showed signals for heavy menstrual bleeding , intermenstrual bleeding, and menstrual clots.
- Tirzepatide generated signals for intermenstrual bleeding and menstrual clots , while liraglutide produced no significant menstrual signals in the age-restricted cohort.
- Semaglutide also produced signals for oligomenorrhea, anovulatory cycle , and menstrual disorder.
- Amenorrhea, irregular menstruation, dysmenorrhea, and polymenorrhea showed no positive associations for all three agents, with Bayesian analyses corroborating all frequentist findings.