What is the first dosage of Wegovy, and why does it start so low?

You've just been prescribed Wegovy, here's what that first pen actually means

Picture the moment you open that first Wegovy box. The pen is loaded and ready, but the dose printed on the label (0.25 mg) is smaller than you might expect. That is deliberate. According to the NHS semaglutide medicines page, Wegovy is started at 0.25 mg weekly for the first four weeks specifically to allow the body to adapt before the dose climbs. If you are wondering whether the first dose of Wegovy is actually doing anything, it helps to know that at this stage most people notice very little change in appetite or weight, and that is not a sign the treatment is failing; the starter phase's job is adjustment, not weight loss.

Semaglutide works as a GLP-1 receptor agonist, mimicking a gut hormone that signals fullness and slows how quickly food leaves the stomach. Hitting the full therapeutic dose from day one would make those effects arrive too fast for many people, triggering nausea, vomiting or diarrhoea severe enough to make them stop altogether. The gradual ramp means that when the meaningful doses arrive (1.0 mg, 1.7 mg, 2.4 mg) the body is already familiar with the mechanism. Think of it less as a delay and more as preparation.

One practical note: if your first pen arrives on a Thursday before a bank holiday, or you ordered just after payday, make sure you know exactly when your four weeks runs out before booking the next prescription review. Timing the dose steps consistently matters, and a prescriber should be in the loop before anything changes. Our page on what happens at your first Wegovy dose covers the practicalities in more detail.

How the dose climbs from 0.25 mg to the maintenance level

After the initial four-week period at 0.25 mg, the standard schedule moves upward in roughly monthly steps: 0.5 mg, then 1.0 mg, then 1.7 mg, reaching the standard maintenance dose of 2.4 mg around week 17. The MHRA has also approved a higher 7.2 mg maintenance dose (and, since 14 April 2026, a dedicated single-dose 7.2 mg pen) for adults with a BMI of 30 or above, though the journey to that level still begins at 0.25 mg and progresses under prescriber guidance. Details on the full range of approved strengths are on our Wegovy doses page.

The word "maintenance" matters. It signals that weight-loss results tend to accumulate at the higher doses, where appetite suppression becomes more consistent. In the STEP 1 clinical trial, published in the New England Journal of Medicine, participants on semaglutide 2.4 mg lost an average of around 15% of their body weight over 68 weeks, the vast majority of that loss happening once they were on the higher therapeutic doses, not during the 0.25 mg phase.

Whether a given person moves through the steps as scheduled, pauses at a lower dose for longer, or needs to revisit an earlier step is entirely a clinical decision. A prescriber weighs tolerability, side-effect history and how the body is responding. Adjusting the schedule yourself (skipping ahead, for instance) risks turning manageable nausea into something that disrupts daily life. If you are comparing costs across the dose journey, our guide to Wegovy pricing in the UK sets out what to watch for.

Side effects that tend to cluster around the first dose and each step up

The side effects most associated with the starting dose and each subsequent step are gastrointestinal: nausea sits at the top of the list, followed by constipation, loose stools, indigestion and, for some people, burping or a general feeling of fullness that extends beyond mealtimes. Fatigue and mild headache are also reported. These effects are usually at their most pronounced in the days following a new dose and then settle as the body recalibrates, often within one to two weeks, though it varies from person to person.

Most people find the 0.25 mg starting dose causes milder symptoms than subsequent steps precisely because the dose is so low. The bigger adjustments often come at the 1.0 mg and 1.7 mg thresholds. Eating smaller portions, avoiding high-fat or high-sugar meals, staying well hydrated and spacing meals across the day rather than having two large ones can all make the transition easier. These are general principles; your prescriber may offer tailored advice based on how you are getting on.

There are symptoms that go beyond standard GI discomfort and need prompt medical attention: severe, persistent stomach pain that radiates toward the back could indicate pancreatitis, which the MHRA flagged in a Drug Safety Update in January 2026 as an infrequent but serious risk with GLP-1 medicines. If you experience that, stop treatment and seek help straightaway. Our page on what to expect from the first dose of Wegovy covers both normal and unusual symptoms in more detail. Suspected side effects can also be reported at the MHRA Yellow Card service.

Who can start at 0.25 mg, and who decides

Wegovy is licensed in the UK for adults with a BMI of 30 or above, or 27 to 29.9 with at least one weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. The licence covers use alongside a reduced-calorie diet and increased physical activity. NICE recommends semaglutide within specialist weight management services, with criteria around comorbidities and BMI thresholds set out in NICE technology appraisal TA875. The private route through a regulated pharmacy like ours follows the licensed criteria rather than the narrower NHS criteria.

The starting dose of 0.25 mg is the same for everyone who begins Wegovy, there is no "lower starter" for people who are particularly sensitive and no "accelerated" entry for people who have taken semaglutide before (unless a prescriber decides otherwise based on your history). Pregnancy, breastfeeding and trying to conceive are reasons the medicine is not recommended; nor is it licensed for under-18s. Anyone with a history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 should not use it.

At nume, a GPhC-registered Independent Prescriber reviews every consultation personally before any treatment is issued. If you are ready to find out whether Wegovy is appropriate for you, you can check your eligibility with our clinical team at no cost and with no obligation. Our wider Wegovy overview page covers the full picture of how the treatment works and what to expect across the programme.