Wegovy Stopped My Period — What's Actually Happening and When to Act

Step 1, Understand why this happens: weight loss, hormones, and the menstrual cycle

The menstrual cycle is exquisitely sensitive to energy balance. Fatty tissue is not passive storage; it actively converts androgens into oestrogen, so when body fat falls quickly it can reduce circulating oestrogen levels enough to disturb the hypothalamic signals that time ovulation. This is the same mechanism behind amenorrhoea in athletes who drop to very low body-fat percentages, and it can happen during any significant period of calorie restriction or rapid weight change, including the kind Wegovy can produce.

Wegovy works by activating GLP-1 receptors, which reduces appetite and slows gastric emptying. The result for many people is a substantial calorie deficit over the first months of treatment. That deficit, rather than semaglutide acting directly on reproductive hormones, is the most likely explanation for menstrual changes reported early in treatment. The NHS medicines page for semaglutide lists common side effects as gastrointestinal, not gynaecological, yet cycle disruption is reported in real-world use often enough that it is worth understanding clearly.

There is also a secondary pathway for some women. Higher BMI is associated with conditions like polycystic ovary syndrome (PCOS), in which elevated insulin resistance disrupts ovulation. As weight falls and insulin sensitivity improves, cycles can actually become more regular, though the transition is not always smooth and can itself look like disruption before it settles.

Step 2, Recognise what's normal variation versus what needs investigating

A period arriving a week later than usual after starting Wegovy, or one that is noticeably lighter during a month of fast loss, sits within the range of changes that weight and energy restriction can cause. That is not a reason to panic, but it is worth tracking.

What warrants prompt attention: a period that stops entirely for more than two consecutive cycles; bleeding that becomes unusually heavy or painful; any bleeding after menopause; or a missed period where there is any possibility of pregnancy. For that last point, the guidance is simple, take a test. Semaglutide is not recommended in pregnancy, and the NHS England guidance on weight-management injections is explicit that effective contraception should be used throughout treatment.

Women using oral contraceptive pills alongside tirzepatide face a specific absorption concern (the pill's effectiveness may be reduced during the first four weeks of treatment and after each dose increase), but current evidence does not identify the same interaction with semaglutide. That said, the broader advice to use reliable contraception applies regardless of which medicine you are taking. Our overview of periods and Wegovy goes into this in more detail if you want to read further.

Step 3, Know when to act, and what your prescriber needs to hear

If you had a regular cycle before starting Wegovy and it has now been absent for two months or more, book an appointment with your GP rather than waiting to see if it returns. Two points matter here: first, the longer amenorrhoea continues the more useful it is to investigate potential causes (thyroid function, prolactin levels, low body weight); second, absence of a period does not mean absence of fertility, so reliable contraception remains essential even when you are not menstruating.

Tell your prescriber or GP exactly when the change started relative to when you began semaglutide, how much weight you have lost over that period, and whether any other symptoms accompanied the change, fatigue, hair thinning, or temperature intolerance can signal thyroid involvement that is worth ruling out separately. For most women the cycle returns to its previous pattern once weight stabilises, usually within a few months of reaching a steady dose. If you are wondering whether weight loss slowing or stopping might also be affecting your cycle, our page on what to do when Wegovy weight loss has stopped covers that ground and may help you understand the fuller picture. Our page on what happens when you stop Wegovy covers that ground clearly.

One practical note: many people find it easiest to log any cycle changes in a period-tracking app alongside their weekly injection day, so that when they do speak to a clinician they have dates rather than impressions. It takes about thirty seconds each week and makes the conversation much more useful.

Step 4, Fertility, contraception, and planning ahead

There is a particular wrinkle worth flagging: weight loss itself can restore ovulation in women who had irregular or absent periods because of obesity or PCOS. That means some women become more fertile during Wegovy treatment at the very moment they may assume their missing period means conception is impossible. The MHRA advises using contraception throughout semaglutide treatment and for a wash-out period afterwards before trying to conceive; your prescriber can advise on the specific timing based on current guidance.

If starting a family is something you are actively planning, this conversation belongs in your consultation before treatment begins, not as an afterthought. A prescriber who knows your intentions can make sure contraception, timing and treatment goals are considered together. You can explore whether Wegovy can stop your period in more detail, or read about the broader range of how Wegovy works as a treatment. For questions about Wegovy's cost or what a private prescription includes, our Wegovy pricing page sets out what is covered transparently. If you are ready to speak with a prescriber, you can start your free consultation and have your questions answered by a real clinician the same day.