Victoza® and menstrual changes

What the product information says

None of the three main documents lists irregular, heavy, missed or painful periods as a reaction to Victoza®. ^[1][2][3] The Canadian monograph’s trial tables, which include every event above 1% in each study, have no menstrual row either. ^[3]

The only cycle-related finding is from animals. In a Canadian juvenile toxicity study, young female rats given the highest dose, about 8.5 times the exposure seen in patients aged 10 to 17, had slightly longer oestrous cycles that returned to normal after treatment stopped. ^[3] This was at a much higher exposure than in patients and does not show an effect in people.

For birth control, the US and EU documents report that Victoza® did not change the overall exposure to the hormones in a combined pill, and Europe expects its contraceptive effect to be unaffected. ^[1][2] The separate page on GLP-1 medicines and the pill covers this in detail.

What research on liraglutide and periods found

Pharmacovigilance. A 2026 analysis of US FDA reports in female patients aged 12 to 55 looked for disproportionate reporting of menstrual problems. ^[4] Semaglutide had the widest set of signals, including heavy and irregular bleeding and infrequent periods, and tirzepatide had signals for bleeding between periods and clots in menstrual blood; liraglutide produced no significant signals. ^[4] Reports cannot give rates or prove cause, and liraglutide is used less often than newer medicines, which limits the analysis.

Trials in polycystic ovary syndrome. PCOS, which MedlinePlus now calls polyendocrine metabolic ovarian syndrome (PMOS), commonly causes irregular periods and insulin resistance. ^[9] In a double-blind trial, 72 women with PCOS received liraglutide 1.8 mg a day or placebo for 26 weeks: weight fell by 5.2 kg more on liraglutide, the bleeding pattern improved more than on placebo, and sex hormone-binding globulin rose while free testosterone fell. ^[5] A 2026 meta-analysis of seven randomized trials with 330 women found liraglutide increased menstrual frequency, with results that varied widely between trials; effects on ovulation and pregnancy could not be pooled. ^[6]

These women did not all have diabetes and some trials used higher doses, so they show what liraglutide can do to cycles in PCOS, not what to expect on Victoza® for type 2 diabetes. ^[5][6]

A missed period: test first

MedlinePlus names pregnancy as the most common cause of secondary amenorrhoea, periods stopping in someone who had regular cycles. ^[8] The documents differ in wording but agree on caution: the US label says Victoza® should be used in pregnancy only if the benefit justifies the risk to the fetus, Europe says it should not be used and recommends insulin, and Canada lists pregnancy as a contraindication. ^[1][2][3] MedlinePlus’s liraglutide page asks you to call your doctor if you become pregnant while using Victoza®. ^[10]

Better blood sugar control and weight loss can change cycles in some women, as the PCOS trials show, which is one reason periods may become more regular on liraglutide in that setting. ^[5][6] NIDDK advises getting blood glucose close to target before a planned pregnancy, because high glucose can harm the baby in the first weeks. ^[11]

Other causes of cycle changes

MedlinePlus lists common causes of abnormal uterine bleeding: hormone imbalance, fibroids, polyps, thickening of the womb lining, bleeding disorders, PCOS, hormonal birth control, infection, and a large weight change in either direction. ^[7] It notes that irregular bleeding is more common in teenagers and in the years before menopause, and that tests may include fasting glucose or HbA1c and thyroid function. ^[7]

For periods that stop, MedlinePlus adds obesity, sudden weight loss, very low body fat, intense exercise, severe stress, an overactive thyroid and some medicines. ^[8] Many of these are relevant to people with type 2 diabetes who are starting treatment and changing how they eat.

Teenagers on Victoza®

Victoza® is approved for type 2 diabetes from age 10, and MedlinePlus notes that young people’s cycles can be 21 to 45 days or more apart. ^[1][7] The only cycle finding in the documents is the reversible change in young rats at high exposure. ^[3] The US and EU documents say side effects in patients aged 10 and older were similar to adults’. ^[1][2] For sexually active teenagers, the pregnancy guidance above applies equally.

What the sources describe

• Take a pregnancy test if a period is late, and tell your prescriber if it is positive. ^[8][10]
• Note the dates, length and heaviness of each period so a provider can see the pattern. ^[7]
• Use contraception if pregnancy is not planned, and discuss with your prescriber before trying to conceive. ^[2][11]
• Keep blood sugar close to target before a planned pregnancy, as NIDDK advises. ^[11]
• See a provider about unusual bleeding or more than one missed period. ^[7][8]

Victoza® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk A/S.

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