Women taking Wegovy and other GLP-1 medications can experience the same side effects reported for all adults, mainly nausea, diarrhoea, vomiting and constipation. In separate trials, hair loss was reported more often in women than in men taking tirzepatide or Foundayo. Some women report changes to their periods while taking these medications. We do not yet know whether the medications themselves are responsible. Very heavy bleeding, or any bleeding after the menopause, should be checked by a doctor.
- The side-effect tables in the Wegovy, Mounjaro and Foundayo labels give one set of figures for all adults, without separate rates for women and men.
- In two tirzepatide weight management trials, hair loss was reported by 7.1% of women and 0.5% of men, and the label links it with weight reduction.
- A 2026 analysis of US adverse event reports found more reports than expected of menstrual changes, such as bleeding between periods, with semaglutide and tirzepatide. Reports of this kind cannot show that a medication caused the change.
- The NHS lists sudden weight loss, being overweight, stress and hormonal contraception among the common causes of a missed or late period.
- Mounjaro and Foundayo can reduce how well the contraceptive pill works for several weeks after starting treatment and after each dose increase.
- Your endocrinologist asks about your periods, contraception and pregnancy plans, and reviews any changes with you at each monthly follow-up.
- The NHS advises seeing a doctor for three missed periods in a row, bleeding between periods or any bleeding after the menopause.
What the labels report about side effects in women
The prescribing information for the GLP-1 medications Wegovy (semaglutide), Mounjaro (tirzepatide), Ozempic (semaglutide) and Foundayo (orforglipron) describes the same main side effects for all adults. Most are digestive, such as nausea, diarrhoea, vomiting and constipation. Ozempic is approved for type 2 diabetes.
In the Wegovy label, 44% of adults on the 2.4 mg injection reported nausea and 30% diarrhoea, compared with 16% for each on placebo. Our pages on the full list of Wegovy side effects and the side effects of Mounjaro give the figures for each medication.
The side-effect tables in these labels do not divide their figures by sex. In the weight management trials described in the tirzepatide label, women made up most of the participants: 37% were men. Where a label does report a difference between women and men, it concerns hair loss and, for Wegovy, fractures in one trial.
Severe stomach pain that does not go away can be a sign of pancreatitis and needs urgent medical care. The same applies to signs of a serious allergic reaction, such as swelling of the face or difficulty breathing, and to being unable to keep fluids down.
Hair shedding in women taking GLP-1 medications
For tirzepatide and Foundayo, hair loss is the one side effect that the labels report separately for women and men. In two of the tirzepatide weight management trials, hair loss affected 7.1% of women and 0.5% of men, against 1.3% and 0% on placebo. The label states that hair loss was associated with weight reduction.
The Foundayo label reports a similar pattern, with hair loss in 7% of women and 0.9% of men, compared with 3% and 0.7% on placebo. For Wegovy, the label gives hair loss as 3% on the injection against 1% on placebo, with no split by sex.
Rapid weight loss, a large calorie deficit, illness or surgery can trigger hair shedding. These stresses can cause more hairs than usual to enter the resting phase together.
The Cleveland Clinic notes that this shedding tends to begin two to three months after the trigger. It often improves within three to six months. The causes and what helps are explained in our article on hair loss on GLP-1 medications.
Period changes reported with GLP-1 medications
A 2026 analysis looked at side-effect reports about women and girls aged 12 to 55, sent to the US Food and Drug Administration (FDA). These reports can highlight possible signals, but they cannot prove that a medication caused the symptom. The analysis found more reports than expected of heavy menstrual bleeding, bleeding between periods, menstrual clots and infrequent periods with semaglutide. For tirzepatide, it found more reports of bleeding between periods and menstrual clots, while liraglutide, an older GLP-1 medication, showed no such signal.
Semaglutide is the active ingredient in Wegovy and Ozempic, and tirzepatide is the active ingredient in Mounjaro. The analysis, by Frey and Etminan, appeared as a research letter in Obstetrics & Gynecology in July 2026.
Reports of this kind come from patients and healthcare professionals, and a single report does not prove that a medication was responsible. They also cannot show how often period changes occur.
Periods can change for other reasons too. The UK National Health Service (NHS) names pregnancy, stress, sudden weight loss, being overweight, too much exercise and hormonal contraception among the common causes of missed or late periods.
The NHS also lists the start of the menopause and polyendocrine metabolic ovarian syndrome (PMOS), previously called polycystic ovary syndrome (PCOS). Our page on PCOS and weight covers that condition in more detail.
Eating very little during treatment may also play a part. Very restrictive diets can also be associated with fatigue, poor concentration, hair thinning and menstrual changes. Our lifestyle coaches can help you plan meals that meet your nutritional needs while your appetite is lower.
When to see a doctor about changes to your periods
The NHS advises seeing a doctor if:
- you have missed three periods in a row
- your periods have become irregular
- you miss a period and have other symptoms, such as tiredness or facial hair growth
- heavy periods are affecting your daily life
- you bleed between periods or after sex
- you have any bleeding after the menopause
The NHS describes heavy periods as needing to change a pad or tampon every one to two hours. Periods that last more than seven days, or clots larger than around 2.5 cm, are also signs of heavy bleeding. The NHS advice on bleeding after the menopause is to see a doctor, even if the bleeding is light or happens only once.
A missed period can also be a sign of pregnancy. If you think you might be pregnant, the Medicines and Healthcare products Regulatory Agency (MHRA), which regulates medicines in the UK, advises contacting a healthcare professional straight away.
If you are an Endocare patient, tell your endocrinologist about any change to your periods at your next follow-up, or sooner if bleeding is heavy.
Bones, menopause and gallstones: other points for women
SELECT was a large cardiovascular outcomes trial of the Wegovy injection in adults with heart disease and overweight or obesity. In this trial, more fractures of the hip and pelvis were reported in women taking Wegovy than in women taking a placebo, at 1% and 0.2%. Our article on bone density on GLP-1 medications covers bone health during weight loss.
Being a woman is one of the gallstone risk factors named by the NHS. Gallstones are a recognised side effect of GLP-1 medications. The symptoms to look for appear in our post on gallbladder problems on GLP-1 medications.
Frequently asked questions
Are Wegovy side effects worse for women?
The Wegovy label does not show this. Its side-effect figures cover all adults together, without separate rates for women and men. Side effects vary from person to person, and your endocrinologist can slow your dose increases if they are troublesome.
Can Mounjaro affect your periods?
It may, although the evidence is limited. In an analysis of US adverse event reports, bleeding between periods and menstrual clots were reported more often than expected with tirzepatide, the active ingredient in Mounjaro. Weight loss, stress and changes in contraception can also affect your cycle. We recommend telling your endocrinologist about any change that continues.
Can Ozempic cause heavy periods?
Heavy menstrual bleeding has been reported with semaglutide, the active ingredient in Ozempic, although these reports do not show that the medication was the cause. The finding covers semaglutide in general, including Wegovy. We recommend seeing a doctor if your periods are heavy enough to affect your daily life.
Does Mounjaro affect the contraceptive pill?
It can, for a limited time. The Mounjaro label advises using a non-oral method, or adding a barrier method, for four weeks after starting treatment and again for four weeks after every dose increase. Foundayo’s label applies the same advice for 30 days. Your endocrinologist can advise on a method that is suitable for you.
Patients should not decide by themselves to start a GLP-1 medication. A doctor’s review is critical to ensure the treatment is safe and appropriate for the individual.
Monthly follow-up appointments can be held in person at the clinic or online. We recommend the first consultation in person, as it includes a physical examination and body composition analysis.
At our Dubai clinic, your endocrinologist will assess you, ask about your cycle, contraception and any pregnancy plans, and review side effects with you at each visit. You can book a weight loss consultation on +971 4 285 3885 or send us a message on WhatsApp.
