What Saxenda® documents cover, and what they leave out
There is no menstrual entry in the US adult or teenage tables, in the EU frequency table or in the Canadian monograph. [1][2][3] The reproductive content is about pregnancy, fertility in animals and puberty in teenagers. For birth control pills, the documents report a single-dose study and the EU and Canadian texts expect the contraceptive effect to be unaffected; the details are covered in our separate birth control article. [1][2][3]
| Topic | What it says | Source |
|---|---|---|
| Period changes as a side effect | Not listed | US 6.1; EU Table 4; Canadian 8 [1][2][3] |
| Pregnancy | US: stop once recognised; EU and Canada: do not use, stop if planning pregnancy | US 8.1; EU 4.6; Canadian 7.1.1 [1][2][3] |
| Miscarriage in trials | 9 of 31 pregnancies on Saxenda®, 2 of 15 on placebo | Canadian 7.1.1 [3] |
| Puberty, ages 12–17 | No effect on growth or pubertal development | EU 4.8; Canadian 8.2.1 [2][3] |
| Cycles in young rats | Slightly longer oestrous cycles that recovered off treatment | Canadian 16 [3] |
| Fertility in animals | No harmful effect apart from slightly fewer live implants | EU 4.6; US 13.1 [1][2] |
What PCOS trials show about cycles
Polycystic ovary syndrome often brings irregular or missed periods, along with insulin resistance and weight gain. [10] Liraglutide has been tested here more than in any other menstrual setting. In a Danish trial, 72 women with PCOS took liraglutide 1.8 mg or placebo for 26 weeks. Liraglutide led to about 5 kg more weight loss, and the ratio of bleeding episodes improved twice as much as on placebo, alongside a rise in sex hormone-binding globulin and a fall in free testosterone. [4]
At the Saxenda® dose, a 32-week placebo-controlled trial in 82 women with PCOS and obesity found 5.7% weight loss on liraglutide 3 mg against 1.4% on placebo, and a lower free androgen index. Digestive side effects affected 58.2% versus 18.5%. [5] Its summary does not report bleeding patterns. Pooling seven randomised trials and 330 women, a 2026 meta-analysis found that liraglutide increased menstrual frequency, though results varied widely between studies, and ovulation and pregnancy could not be pooled. [6]
These trials studied women with PCOS. They do not show what happens to cycles in women without it, and Saxenda® is not approved to treat PCOS.
Why your cycle may shift on Saxenda®
- Weight change: MedlinePlus lists obesity and also sudden, large weight loss as reasons periods can stop, and severe weight loss or gain among causes of abnormal bleeding. [8][9]
- Underlying PCOS: if it was present but unrecognised, weight loss may change a previously irregular pattern, as the trials above suggest. [4][6][10]
- Pregnancy: the most common cause of a missed period. [8] Better ovulation in PCOS trials is one reason a pregnancy test matters. [4][6]
- Stress and illness: severe anxiety, very hard exercise, thyroid problems and several medicines can also stop periods. [8]
- Teen cycles: periods can take a few years to become regular, and girls’ cycles vary widely. [7][9] In the Saxenda® adolescent trial, puberty was not affected. [2][3]
The pregnancy rules in plain terms
The US label no longer lists pregnancy as a contraindication, but it states that Saxenda® may cause harm to a developing baby, that weight loss offers no benefit in pregnancy, and that Saxenda® should be stopped once a pregnancy is recognised. [1] The EU and Canadian documents go further: Saxenda® should not be used in pregnancy, and treatment should be stopped if a woman wishes to become pregnant. [2][3]
In the Saxenda® trials, more of the pregnancies that occurred ended in miscarriage on Saxenda® than on placebo, 9 of 31 against 2 of 15; the numbers are small. [3] Saxenda® is a daily injection, so stopping is a matter of not taking the next dose, but timing and next steps should be agreed with your prescriber.
Keeping track, and what helps
MedlinePlus suggests noting your period each month so you know your usual pattern and can spot changes. [7] Most cycles run about 28 days, and shorter or longer cycles can still be normal. [7] It advises talking to a provider about major changes, very heavy bleeding or severe pain, and seeing a provider if you miss more than one period. [7][8]
For PCOS, MedlinePlus lists a healthy weight, regular activity and healthy eating as lifestyle steps that can ease many symptoms, with hormonal medicines as options when pregnancy is not planned. [10] If you vomit or have diarrhoea around the time you take a birth control pill, ask a pharmacist what to do; the birth control article sets out what the GLP-1 labels say.
Saxenda® 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
- A positive pregnancy test while on Saxenda®
Contact: Your prescriber; stop Saxenda® as the label directs
US label 8.1 [1]
- A late period with any chance of pregnancy
Contact: Take a pregnancy test; contact your prescriber if positive
- Unusual vaginal bleeding, very heavy periods or severe period pain
Contact: Your doctor or gynaecologist