Wegovy information sheet: what this medicine does, who it suits, and what to expect

How Wegovy actually works in the body, and why that matters for your decision

Semaglutide is a synthetic version of GLP-1, a gut hormone your body releases naturally after eating. Wegovy mimics that signal at a much higher level than food alone produces, binding to GLP-1 receptors in the brain's appetite centres and in the gut wall. The result is a meaningful reduction in hunger, a slower rate of gastric emptying, and an earlier sense of fullness. For most people this combination makes eating less feel manageable rather than effortful.

That mechanism is why Wegovy is categorised as a medicine rather than a supplement or a diet aid. It changes physiology, not just habits, and that is also why it carries the same risks and responsibilities as any serious prescription treatment. The NHS semaglutide medicines page explains how the medicine works in plain language and lists what the prescriber needs to know about your health before prescribing it. Reading that page in the ten minutes before your consultation is a genuinely useful way to arrive prepared.

Wegovy is taken once a week by subcutaneous injection, typically into the abdomen, thigh, or upper arm. The injection site should be rotated. Storage requires refrigeration between 2°C and 8°C; the wegovy patient information sets out the exact room-temperature window if you need to travel, alongside other practical guidance you will want before your first dose. For a full summary of clinical detail, the Wegovy SmPC on the eMC is the definitive reference and is freely accessible to patients.

Who the evidence suggests Wegovy suits, and where the limits are

The UK licence covers adults with a BMI of 30 or above, or a BMI between 27 and 29.9 alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, dyslipidaemia, or obstructive sleep apnoea. Lower BMI thresholds apply for South Asian, Chinese, Middle Eastern, Black African, and African-Caribbean backgrounds, in line with UK clinical guidance. BMI alone never settles the question, the prescriber also looks at your medical history, any medicines you take, and conditions that might make Wegovy unsuitable.

Wegovy is not recommended during pregnancy, while breastfeeding, or if you are actively trying to conceive. It is not licensed for anyone under 18. If you take an oral contraceptive pill, current NHS guidance suggests using an additional non-oral method of contraception for the first four weeks of treatment, because GLP-1 medicines can affect how quickly oral medicines are absorbed. If you are considering HRT, discussing the route of administration with your doctor before starting Wegovy is sensible.

The NICE appraisal of Wegovy (TA875) sets stricter criteria for NHS prescribing, a maximum of two years, within a specialist weight management service. Private prescribing follows the licensed criteria instead, which is broader. You can read more about how private treatment through a regulated service differs from the NHS route on the Wegovy treatment overview page.

What to expect from results, and how realistic the trial figures are

The STEP 1 trial (68 weeks, semaglutide 2.4 mg versus placebo, published in the New England Journal of Medicine) reported an average weight reduction of around 15% in the treatment group alongside lifestyle intervention. That is a population average across thousands of participants with varied starting points, and individual results sit above and below it. The medicine is not a guarantee of any specific outcome.

Progress at six months matters clinically: if someone has not lost at least 5% of their starting weight by that point on the maintenance dose, the prescriber will review whether continuing is the right course. Wegovy works best as part of a broader pattern, adequate protein, hydration, and some resistance exercise help preserve muscle mass while weight falls. Your prescriber or a dietitian can help tailor that advice to your situation.

A newer, higher 7.2 mg dose of Wegovy was approved by the MHRA in April 2026, with trial data suggesting around 20.7% average weight loss over 72 weeks, approaching results seen with tirzepatide at its highest dose. Whether a specific dose or pen format is available to you is confirmed at consultation; our wegovy product information page explains how titration typically progresses and covers the different pen formats available. If cost is a factor in your thinking, the Wegovy pricing context page sets out what UK private treatment typically costs and what any honest price includes.

Side effects to know about before you start

The most common side effects are gastrointestinal: nausea, loose stools, constipation, indigestion, and burping are all reported, particularly during the first weeks of a new dose. These usually settle as the body adjusts. Fatigue and mild headaches are also common early on. Injection-site reactions are possible but generally minor.

Less commonly, Wegovy can affect the gallbladder; gallstones are a recognised risk with significant weight loss by any means, and Wegovy is no exception. The MHRA's Drug Safety Update in January 2026 highlighted acute pancreatitis as an infrequent but potentially serious risk across GLP-1 medicines: if you experience severe stomach pain that spreads to your back, with or without vomiting, seek medical attention promptly rather than waiting for a scheduled review.

Any suspected side effect can be reported directly at the MHRA Yellow Card scheme. That reporting system is how regulators monitor medicines in real-world use, and patient reports genuinely contribute to safety monitoring. If at any point you have questions between doses, the aftercare team at nume is available seven days a week. For a broader look at whether this medicine fits your circumstances, our wegovy information page covers the background detail worth reading before you decide, and if you would like to explore the full picture on how the medicine is used and what to expect, our dedicated information about Wegovy brings together the clinical and practical detail in one place, and the free consultation is where our prescribers review your full picture, the same day, every working day.