The Wegovy jab: evidence, eligibility and what to realistically expect

What the STEP 1 trial actually showed, and why the number matters

The headline figure from the STEP 1 trial is 15% average body-weight reduction over 68 weeks. That comes from a study of nearly 2,000 adults with obesity or overweight plus at least one weight-related condition, all of whom received lifestyle support alongside the injection. It is worth being precise about this: the 15% is an average across participants using semaglutide 2.4mg, meaning some lost considerably more and some less. Results vary based on diet, activity, adherence and individual biology.

Since the STEP 1 data were published, Novo Nordisk developed a higher-dose option. The MHRA approved the single-dose 7.2mg Wegovy pen on 14 April 2026 for adults with a BMI of 30 or above. Trials at that strength reported around 20.7% average weight loss over 72 weeks. The titration pathway still starts at 0.25mg, the higher dose is a maintenance ceiling reached gradually, under prescriber supervision, not a starting point.

One misconception worth clearing up gently: some people assume the jab works independently of lifestyle changes. The licensed indication, and the trial design, both include a reduced-calorie diet and increased activity alongside the medicine. If you want to understand more about how this treatment works in practice, our page on the Wegovy slimming jab explains the appetite and satiety mechanisms, and why the habits that sustain weight loss long term remain essential.

How the Wegovy jab is taken and what the dose schedule looks like

Wegovy is injected subcutaneously (into the fat layer beneath the skin) once every seven days. The three main sites are the abdomen, the thigh and the upper arm; rotating the site each week is recommended to reduce local reactions. For practical guidance on choosing injection sites, the best place to jab Wegovy is covered separately.

The dose escalation follows a structured path set by the prescriber: 0.25mg for the first four weeks, then 0.5mg, then 1.0mg, then 1.7mg, before reaching 2.4mg as the standard maintenance dose. Each rung on that schedule exists to give the body time to adjust, most of the gastrointestinal side effects are most noticeable when the dose increases and tend to settle within a week or two. The prescriber decides whether to pause at a given dose for longer if tolerability is a concern. Dosing decisions, including the timing of increases, stay with your prescriber and the Patient Information Leaflet. For a broader overview of what semaglutide is and how it is used, the NHS semaglutide medicines page is a reliable reference.

Storage follows the standard requirement for pre-filled biological pens: refrigerated between 2°C and 8°C. The exact room-temperature window for short-term storage is detailed in the leaflet that comes with each pen, check that rather than relying on general summaries.

Who the Wegovy jab is licensed for, and where NHS access currently stands

The UK licence covers adults with a BMI of 30 or above, or 27 to 29.9 alongside at least one weight-related condition such as hypertension, type 2 diabetes, dyslipidaemia or obstructive sleep apnoea. Lower BMI thresholds can apply for some ethnic backgrounds under UK clinical guidance, specifically a 2.5 kg/m² reduction for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean heritage.

NHS access follows the criteria in NICE technology appraisal TA875, which recommends semaglutide for weight management for a maximum of two years, within a specialist multidisciplinary weight management service, for adults with a BMI of 35 or above and at least one weight-related comorbidity. NHS waiting lists for specialist services are commonly long. If you are considering going private, our page on the Wegovy weight loss jab explains what private treatment involves, including how clinical assessment works through a regulated online pharmacy, where eligibility is determined by a prescriber rather than by ticking a BMI box. A brief overview of what private treatment typically costs is available on our Wegovy prices page.

Treatment is not recommended during pregnancy, while breastfeeding, or when actively trying to conceive. It is not licensed for anyone under 18. These are not administrative rules, they reflect the absence of safety data in those groups, and your prescriber will ask about them as part of every assessment.

Side effects to be aware of before starting the Wegovy jab

The most common side effects are gastrointestinal: nausea, vomiting, diarrhoea, constipation, reflux and burping appear frequently, particularly in the early weeks and around each dose increase. Most people find these settle as the body adjusts. Fatigue, headache, dizziness and injection-site reactions are also reported. The full semaglutide profile covers these in more depth.

Less common but more serious: acute pancreatitis is a known risk with GLP-1 medicines. Severe, persistent stomach pain that spreads to the back (with or without vomiting) is a reason to seek urgent medical attention, not wait to see if it passes. Gallbladder problems, symptoms of dehydration from persistent vomiting or diarrhoea, and allergic reactions also warrant prompt care. If you experience side effects and want to report them, the MHRA's Yellow Card scheme accepts reports directly from patients.

People using oral contraceptives should discuss contraception with their prescriber before starting, as absorption of the pill may be affected during the early weeks of treatment and around dose increases. Transdermal options (patches or gels) avoid this concern. The question of whether the Wegovy injection is similar to or different from other weight-loss jabs people may have read about is explored on our fat jab semaglutide page. If you are ready to find out whether you are clinically suitable, start your free consultation with our prescribing team.