Your First Dose of Wegovy: What to Expect

Why the 0.25 mg starting dose exists — and what the trial data showed

The STEP 1 trial, published in the New England Journal of Medicine, followed 1,961 adults with obesity over 68 weeks. Participants reached the 2.4 mg maintenance dose through a structured escalation, starting low. At that maintenance level, average body weight fell by around 15%. That figure gets quoted widely, but it only became possible because participants spent the early weeks at doses like 0.25 mg, building tolerance before the medicine could do its clinical work.

The rationale is physiological. Semaglutide slows gastric emptying and acts on appetite-regulating centres in the brain. At full dose, those effects are pronounced. If you want to understand exactly what to expect when you begin, our page covering the start dose of Wegovy walks through the reasoning in detail, including why 0.25 mg is the correct beginning of treatment rather than a reduced version of it.

A question our prescribers hear most weeks is whether it is worth skipping ahead to a higher dose sooner. The answer, consistently, is no, not because of an arbitrary rule, but because the evidence behind the titration schedule was built into the trial design itself. The gradual Wegovy dosing pathway exists because it produces better tolerability and, ultimately, better outcomes.

What happens on the day of your first injection

The NHS semaglutide patient page outlines the practical steps clearly. You inject subcutaneously (just under the skin) in the abdomen, thigh, or upper arm, rotating the site each week. The pre-filled Wegovy pen is designed to be used once a week, on the same day. Most people find a day that fits their routine and stick to it.

After the first injection, the most common early experience is mild nausea. This is not a sign something has gone wrong. It reflects the medicine's action on the digestive system and, for the majority of people, settles within days to a couple of weeks. Keeping meals smaller and lower in fat in the first few days can help. Staying well hydrated matters too, particularly if nausea leads to reduced appetite.

Injection-site reactions (a little redness or tenderness) are also possible and generally brief. If you are uncertain about technique, your prescriber or the Patient Information Leaflet that comes with your pen is the right place to check. The pen format and dosing details are worth reviewing before your first use, so you are not consulting the instructions for the first time with a pen in hand.

The escalation that follows (from first dose to maintenance

After four weeks at 0.25 mg, the prescriber-led schedule moves to the Wegovy 0.5 mg dose, which is the first step up and the point at which many people begin to notice a more perceptible effect on appetite. From there the schedule continues to 1.0 mg, then 1.7 mg, and finally to 2.4 mg, each step held for approximately four weeks. That is the standard maintenance dose and the level at which the clinical evidence base is strongest. For those who need or are clinically suitable for more, the MHRA approved a higher 7.2 mg dose in 2026, though the starting point remains the same for all patients: 0.25 mg, always.

Titration is not automatic. Your prescriber reviews progress, tolerability and clinical indicators before confirming each step up. If a particular dose causes significant side effects, remaining at that level a little longer is a recognised clinical approach, moving up before the body is ready tends to worsen gastrointestinal symptoms without improving results. This is one reason the full schedule of Wegovy doses is managed through ongoing clinical oversight rather than a fixed calendar.

It is worth understanding that meaningful weight loss is not expected at 0.25 mg. The STEP 1 results were achieved at 2.4 mg across a 68-week programme. Measuring the success of your first dose by what the scales show in week one misses the point of how the treatment is structured. The first dose does its job by keeping you in treatment long enough for the later doses to do theirs. For context on what the full course looks like, the weight-loss treatment overview covers how different options compare.

Safety signals to know before you start

Wegovy is a prescription-only medicine for a reason. Certain conditions and circumstances mean it is not suitable. It is not recommended during pregnancy, when breastfeeding, or if you are trying to conceive. It is not licensed for under-18s. Specific conditions affecting the pancreas, gallbladder or thyroid require careful prescriber assessment before treatment begins.

In January 2026, the MHRA issued a Drug Safety Update drawing attention to acute pancreatitis as an infrequent but serious risk with GLP-1 medicines. The key symptom to act on is severe, persistent stomach pain (especially if it radiates toward the back) with or without vomiting. This requires urgent medical attention. Reporting any suspected side effects through the MHRA Yellow Card scheme helps the regulator monitor safety across the population using these medicines.

Women using oral contraceptives should be aware that tirzepatide specifically requires an additional non-oral contraceptive method at the start of treatment; for semaglutide, current NHS guidance does not identify the same effect on pill absorption, though discussing contraception with your prescriber remains sensible. If you have questions about whether Wegovy is appropriate for your situation, our clinical team is the right place to start that conversation.