How semaglutide can affect your period — and what to do about it

Why semaglutide changes periods: the hormone chain to understand

When body weight falls at pace, fat tissue (which produces oestrogen) decreases. That reduces the amount of oestrogen circulating in the body, which can disrupt the hormonal signalling that governs ovulation and the menstrual cycle. It is not that semaglutide is targeting the uterus; the medicine is changing the metabolic environment, and the cycle responds to that change.

There is also a second thread worth knowing. Polycystic ovary syndrome (PCOS) affects a significant proportion of people with obesity, often suppressing or irregularising periods. As insulin sensitivity improves and weight falls on semaglutide, some people find their cycles become more regular rather than less, sometimes for the first time in years. So the same medicine can push in opposite directions depending on where someone starts.

Stress, sleep, and calorie restriction (which often accompanies treatment) can add further variability. The overall effect semaglutide has on periods is, in short, highly individual. If you have been living with irregular cycles and are now noticing changes, that context matters when you speak to a prescriber. You are not imagining it, and there is usually a reason.

The specific changes most commonly reported, and when to take them seriously

The most frequently described changes are cycles arriving earlier or later than expected, periods becoming lighter, and occasional missed periods in the first three to six months of significant weight loss. Some people also notice the reverse: heavier or more prolonged periods when hormonal patterns shift. Neither direction is inherently alarming on its own, but both are worth noting.

A missed period when you are taking semaglutide and are sexually active should prompt a pregnancy test. This is not a precautionary reflex, it reflects a genuine mechanism. As weight falls, fertility can return or increase, sometimes before any cycle change makes that obvious. The question of periods stopping on Wegovy is one of the most common things prescribers field, and the honest answer is that the cause needs ruling in before it can be managed.

Seek medical advice promptly if you experience very heavy bleeding (soaking through more than one pad per hour for several hours), severe pelvic pain, or any bleeding after a confirmed pregnancy. These are not expected effects of semaglutide and need assessment in their own right, independent of your weight-loss treatment.

Contraception: the practical decision this raises

Increased fertility during weight loss is well-established, and NHS guidance is clear: use effective contraception while on GLP-1 medicines and for a wash-out period before trying to conceive. If you are on oral contraceptives and are starting or increasing a dose of semaglutide, the evidence base suggests no significant reduction in pill absorption, unlike tirzepatide, where NHS guidance specifically recommends adding a non-oral method for the first four weeks of treatment and for four weeks after each dose increase.

That distinction matters. If you are considering switching between treatments or are already on one and unsure whether your contraceptive is still reliably absorbed, this is exactly the kind of question worth raising with a prescriber rather than resolving by assumption. The relationship between Wegovy and your cycle has practical implications that go beyond period tracking, and a brief clinical conversation can clear them up. There is a broader overview of what Wegovy is and how it works if you are still building up that picture.

Semaglutide is not recommended during pregnancy or breastfeeding, or when actively trying to conceive. If you are planning a pregnancy, discuss timing with your prescriber well in advance. The NHS England guidance on weight-management injections addresses contraception and reproductive health in detail and is worth reading alongside your prescriber's advice. NHS England's guidance on weight-management injections sets this out clearly.

When to bring this up with a prescriber, and how nume fits in

If your cycle has changed noticeably since starting semaglutide, you do not need to wait for a scheduled review to raise it. Changes to period pattern, unexpected weight on the heaviest end of the spectrum, missed periods with a negative test, or anything that worries you are all reasonable reasons to get in touch with whoever oversees your treatment. At nume, aftercare is available seven days a week, there is no queue to join for a concern that does not fall neatly on a weekday.

If you are thinking about starting semaglutide and want to understand how it might interact with your cycle before you commit, that is a sensible question to bring to a consultation. Prescribers at our clinical team review each consultation personally, not by algorithm, and reproductive health factors form part of a thorough clinical picture. If you would like a sense of what private treatment costs before you take that step, the Wegovy price comparison page covers what UK pricing typically includes.

The right moment to discuss any of this is sooner rather than later. Check your eligibility and speak to our prescribers whenever you are ready.