What is known
Menstrual changes are not among the adverse reactions in the Wegovy or Zepbound labels.[1][2] We found no trial that measured menstrual cycles as an outcome in people taking these drugs for weight.
Two related facts
- Birth control pills. The Zepbound label says tirzepatide may make oral contraceptives less effective, and advises a non-oral or backup method for 4 weeks after starting and after each dose increase.[2] A change in bleeding pattern on the pill can be a sign it is not working as expected.
- Pregnancy. A missed period is a reason to take a pregnancy test; both labels say to stop the drug when pregnancy is recognized, or, for Wegovy, at least 2 months before a planned pregnancy.[1][2] See pregnancy and birth control.
Weight loss on its own can change menstrual cycles, especially in people whose cycles were irregular before; this is general knowledge about weight and hormones, not a GLP-1 finding.
When to get checked
- A missed period: pregnancy test
- Very heavy bleeding, soaking a pad or tampon every hour, or bleeding with dizziness
- Bleeding after menopause
The short version
Short on the way. A 35-second captioned version of this page is in production for the Fewer Bites channel. It will be embedded here when it is live.
Questions to bring to your prescriber
Print these or screenshot them. They are conversation starters, not a checklist of things to do.
- My cycle has changed since I started: is that worth looking into?
- Is my current birth control reliable with this medicine?
Education, not advice. This page explains what trials, labels and guidelines report. It does not tell anyone to start, change or stop a medicine. Your prescriber knows your history; this page does not.
Sources
- Novo Nordisk / FDA. Wegovy (semaglutide) injection and tablets, prescribing information, revised 06/2026. label
- Eli Lilly / FDA. Zepbound (tirzepatide) prescribing information, revised 08/2026. label