Your first month on Wegovy: what actually happens

Week one: the pen is in, but not much else has changed yet

You have just done your first injection. The dose is 0.25mg — low enough that many people feel almost nothing different in the first few days. That is intentional. The starting dose exists to let your digestive system acclimatise to semaglutide before the therapeutic work begins; it is not meant to produce dramatic appetite suppression on its own.

What some people do notice, even this early, is a subtle shift in how quickly they feel full. Meals that normally felt routine start feeling like enough with a little less on the plate. Others notice nothing yet, and that is equally normal. Either way, the medicine is beginning to slow gastric emptying and signal to the brain's appetite centres, the effect just builds gradually rather than arriving all at once.

Side effects this week tend to be mild for most people: a bit of nausea after eating, occasional loose stools, or some reflux. Eating smaller portions, keeping meals lower in fat, and staying hydrated all help. A practical habit worth building from day one: check your injection-site area each week and rotate between the abdomen, thigh, and upper arm. It takes under a minute and avoids the localised reactions that come from reusing the same spot.

Weeks two and three: appetite shifts become harder to ignore

By the second and third week, the appetite signal tends to become more noticeable. The clinical term is reduced caloric intake, but in practice it feels more like forgetting to be hungry, or putting your fork down earlier than usual without consciously trying to. Some people describe it as the internal noise around food quietening down.

This is also when side effects can peak for some people, particularly around any dose increase. Nausea, burping, constipation, and general digestive sluggishness are the most commonly reported, consistent with what the NHS semaglutide medicines page lists as the known GI profile of this drug class. For the majority these settle within a few days of each new dose; for a minority they linger longer. Staying well hydrated and eating smaller, more frequent meals tends to make the biggest practical difference.

Weight change at this stage varies enormously between individuals. Some people see a noticeable drop on the scales; others see little movement yet. Both are within the expected range. The medicine is working on appetite regulation and metabolism, the weight reduction follows the sustained calorie deficit it creates, and four weeks is a very short window for that to accumulate. By month three, the picture is usually clearer.

Week four: what a realistic end-of-month assessment looks like

At the four-week mark, a fair question to ask yourself is not "how much have I lost?" but "am I tolerating the medicine, and is my appetite changing?" Those two things matter more than the number on the scales right now.

Clinical trial evidence for semaglutide 2.4mg (the STEP 1 trial, published in the New England Journal of Medicine) showed an average weight reduction of around 15% over 68 weeks. That is a 68-week figure. In the first month, participants were still on the lowest doses, still adjusting. The trajectory matters more than where you are after 30 days.

If side effects have been severe or persistent, that is worth discussing with your prescriber, not something to push through alone. If you are curious about what comes next, what happens after the first month of Wegovy covers the transition into the dose-escalation period and what to expect as treatment matures. For a broader look at the treatment itself, the Wegovy overview sets out the full licensed context, eligibility, and how semaglutide works across the full course.

Pricing is a practical question that comes up at this stage too, once people are committing to continuing. A factual comparison of what different providers include (and what some leave out) is set out on our Wegovy price comparison page.

If you are considering starting treatment, or want a prescriber to review how your first month has gone, our team is available seven days a week. Speak to our prescribers through a free consultation, every assessment is done personally, the same day, by a GPhC-registered Independent Prescriber.