What the Ozempic® documents cover
Menstrual changes do not appear among the adverse reactions in any of the three documents. [1][2][3] What they do contain concerns cycles indirectly: animal fertility findings, the contraceptive pill and pregnancy.
| Topic | What the document says | Source |
|---|---|---|
| Menstrual changes as a side effect | Not listed | US, EU and Canada [1][2][3] |
| Female rats | Longer oestrous cycles and slightly fewer ovulations, likely adaptive to lower food intake and weight | US section 13.1; EU 4.6 [1][2] |
| Human fertility | Effect unknown | EU section 4.6 [2] |
| Combined pill | Ethinyl estradiol unchanged; levonorgestrel exposure up 20%; not expected to reduce pill effect | EU section 4.5 [2] |
| Oral medicines in general | Delayed stomach emptying may affect absorption; use caution | US section 7.2 [1] |
| Pregnancy | US: only if benefit justifies risk; EU: should not be used; stop at least 2 months before a planned pregnancy | US 8.1, 8.3; EU 4.6 [1][2] |
What FDA adverse event reports show
A 2026 study in Obstetrics & Gynecology analysed FDA reports through March 2026 for women aged 12 to 55. Semaglutide had the broadest set of signals: heavy menstrual bleeding, bleeding between periods, menstrual clots, infrequent periods and cycles without ovulation were reported more often than expected. Tirzepatide showed signals for bleeding between periods and clots; liraglutide showed none. [4] The authors suggested that menstrual health be part of counselling for women of reproductive age.
A separate 2026 analysis of the same reporting system for 2022 to 2025 found semaglutide associated with reports of polycystic ovary syndrome and menstrual abnormalities, while dulaglutide and tirzepatide had lower reporting for terms such as painful periods, absent periods and heavy bleeding. [5]
These are pharmacovigilance studies. They show which events people chose to report, not how often events happen or whether the medicine caused them. Reporting can rise with publicity, and many women prescribed semaglutide already have PCOS, diabetes or significant weight change, all of which affect cycles. [4][5][7]
PCOS: periods that become more regular
Polycystic ovary syndrome often causes irregular or absent periods and is linked to insulin resistance; NIDDK notes that PCOS and obesity, both connected to diabetes, can make conceiving harder. [8] A 2026 scoping review of 25 studies of semaglutide in women with PCOS reported weight loss of about 7.6 to 11.5 kg over 3 to 6 months, better insulin measures and, in several studies, more regular cycles. [6]
The review graded this evidence as preliminary: much of it came from conference abstracts and small pilot studies. It also flagged a practical risk, inadvertent pregnancy once ovulation returns, and stressed that semaglutide must be stopped before a planned conception. [6] None of the PCOS work tested Ozempic® as a diabetes treatment specifically.
Why a cycle might change on Ozempic®
- Label-supported: semaglutide reduces food intake and body weight, and in rats the cycle changes were attributed to exactly that. [1]
- General medicine: MedlinePlus lists severe weight loss, weight change of more than about 4.5 kg, PCOS, hormonal contraception and being overweight among causes or risk factors for abnormal uterine bleeding. [7]
- Proposed: improved insulin resistance could restore ovulation in some women, which may explain both more regular periods and the PCOS findings. [6] This has not been measured in Ozempic® trials.
- Other causes to keep in mind: fibroids, polyps, thickened uterine lining, infection, clotting problems, thyroid or hormone problems, approaching menopause and, rarely, cancer. [7]
Pregnancy planning with diabetes
The US Ozempic® label sets its pregnancy advice against the risks of diabetes itself. It notes that the background risk of major birth defects is 6 to 10% in women with pre-existing diabetes and an HbA1c above 7, and has been reported as high as 20 to 25% with an HbA1c above 10, compared with 2 to 4% in the general population. [1] It says Ozempic® should be used in pregnancy only if the benefit justifies the risk, while the EU summary says it should not be used during pregnancy and recommends contraception. [1][2]
Both documents ask women to stop Ozempic® at least 2 months before a planned pregnancy because semaglutide stays in the body for a long time. [1][2] NIDDK adds that getting blood glucose close to target before conceiving is important, because high glucose can harm a baby in the first weeks, often before pregnancy is known. [8] A period that is late, or one that returns after a long gap, is therefore worth acting on promptly.
Tracking and when to seek advice
MedlinePlus advises contacting a provider about any unusual vaginal bleeding and describes heavy bleeding as passing large clots, needing to change protection overnight, or soaking a pad or tampon every hour for 2 to 3 hours in a row. Bleeding for more than 7 days, cycles shorter than 28 or longer than 35 days, and bleeding between periods are also abnormal patterns. [7] Losing a lot of blood over time can cause tiredness from anaemia. [7]
Note your period dates, flow and any clots alongside your Ozempic® dose history and weight. That record helps a clinician separate drug, weight and hormone effects. [7]
Ozempic® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
The signs and contact information below come from this article’s sourced guidance.
Today
- Very heavy bleeding, such as soaking a pad or tampon every hour for 2 to 3 hours in a row
Contact: Your provider, promptly
MedlinePlus [7]
- A missed period or positive pregnancy test while using Ozempic®
Contact: Your prescriber, the same day
- Any bleeding during pregnancy
Contact: Your provider
MedlinePlus [7]