No period on Wegovy — should you be worried?

Why does Wegovy affect periods in the first place?

Semaglutide works by mimicking GLP-1, a gut hormone involved in appetite regulation, slowing gastric emptying and reducing calorie intake. The NHS overview of semaglutide covers the mechanism in plain language, but the menstrual angle isn't directly addressed there, which is exactly why this question keeps coming up.

The connection between weight and cycles is direct. Body fat produces oestrogen; lose a meaningful amount of weight quickly, and oestrogen levels shift. That shift can delay or suppress ovulation. If you want to understand more about the wegovy effect on period length and regularity, the picture starts here with how the hypothalamus, which acts as the conductor for reproductive hormones, responds to energy availability, and when Wegovy cuts appetite significantly, the body may read that reduction as a signal to pause non-essential processes, including ovulation.

This isn't a sign the medicine is doing something wrong. It's the same mechanism seen in people who lose weight through any route, including surgery or intensive dietary change. The difference with Wegovy is that the weight loss can arrive quickly, sometimes before the body has adjusted to the new energy balance.

Stress, sleep disruption, and the general upheaval of starting a new treatment can all pile on top. Cycles that were already irregular before treatment tend to be more reactive to these changes.

Is a missed period on semaglutide always down to the medicine?

Not necessarily, and this matters. One thing worth doing immediately (before settling on Wegovy as the explanation) is a pregnancy test. Semaglutide does not prevent pregnancy, and there is evidence suggesting fertility can improve as weight changes, sometimes faster than people anticipate. A negative test at least narrows the picture.

Polycystic ovary syndrome (PCOS) is another factor worth considering. PCOS affects a significant proportion of people with higher BMIs, often causing irregular cycles independently of any medicine. As weight changes on treatment, PCOS symptoms can shift too, sometimes improving, sometimes making cycles temporarily less predictable. Our page on periods and Wegovy covers the PCOS angle in more detail.

Thyroid changes, stress, and other medicines can also be in play. A missed single period, in isolation, with no other symptoms, is often low urgency. For a broader look at the wegovy effects on period patterns over time, including what counts as a concerning change versus a temporary disruption, it is worth reading through the evidence before deciding whether a pattern of absent periods over two to three months, or periods accompanied by new pain or unusual bleeding, warrants a GP review rather than a watchful wait.

The question of whether semaglutide directly suppresses ovulation (beyond the weight-mediated route) is still being studied. The honest answer is that the evidence is not yet definitive on the direct hormonal mechanism.

What should you actually do if your period has stopped?

First, rule out pregnancy. That's the practical step, not the clinical footnote. If the test is negative and you're a few weeks into a missed period, note when your last period arrived, what your cycle was like before starting Wegovy, and whether anything else has changed, travel, illness, significant stress, dose increase.

If you're using oral contraception alongside tirzepatide, the guidance differs slightly; you can read about how semaglutide affects the cycle and how that compares to guidance for other GLP-1 medicines. For Wegovy specifically, people sometimes ask can Wegovy stop your period altogether, and there is no current MHRA instruction to switch away from oral contraceptives, but discussing this with your prescriber is sensible if you're relying on the pill as your sole contraceptive method.

Reach out to your prescriber or GP if: periods have been absent for three or more months; you have pain, unusual discharge or other pelvic symptoms; or you're trying to conceive and the cycle disruption is affecting that. At nume, our clinical team reviews every patient's ongoing situation, and questions like this are exactly what aftercare is for. You can also browse our FAQs for other common concerns, or get in touch directly.

For context on how Wegovy works and what the full treatment picture looks like, the Wegovy treatment page is a useful reference. If you're still weighing up whether to start or continue, our free consultation is the right next step, a prescriber can look at your specific situation rather than a general answer.

One practical note worth flagging: if you are not actively trying to conceive, using effective contraception throughout Wegovy treatment is the standard recommendation, in line with NHS England's guidance on weight-management injections. Fertility can return before cycles normalise, which is a detail that catches people off guard.