Novo Nordisk's Wegovy: the semaglutide weight-loss injection explained

You've heard the name everywhere — here's what Wegovy actually is

Chances are you've seen Wegovy mentioned in a news article, heard it from a friend, or come across it while looking into options for managing your weight. It's a lot to wade through. The short version: Wegovy is the brand name Novo Nordisk uses for a specific formulation of semaglutide, a medicine originally developed to treat type 2 diabetes and later approved for weight management at a higher dose, and you can find a detailed look at Novo Nordisk's Wegovy product and how the company positions it if you want the manufacturer's perspective alongside the clinical picture.

Semaglutide belongs to a class called GLP-1 receptor agonists. GLP-1 is a hormone your gut releases after eating; it signals to your brain that you're full and slows the rate at which your stomach empties. Wegovy mimics that signal, which is why many people find their appetite falls significantly on treatment. It isn't a stimulant, a meal replacement or a fat-blocking capsule. It works with your body's own hormonal system, a point that becomes clearer when you read about the Gila lizard research that first put semaglutide's predecessor on scientists' radar.

One thing worth knowing: semaglutide also comes as Ozempic, which is a lower-dose version licensed for type 2 diabetes management, not weight loss. The two are not interchangeable. You can read more about how semaglutide works across its different uses if that distinction matters to your situation. On this page, everything refers to Wegovy specifically, Novo Nordisk's weight-management formulation.

What the clinical evidence shows for Novo Nordisk's Wegovy

The headline figure comes from the STEP 1 trial: adults with obesity using semaglutide 2.4 mg alongside a reduced-calorie diet and increased activity lost around 15% of body weight on average over 68 weeks, compared with around 2.4% in the placebo group. That is a meaningful difference, and it's the trial that underpinned Wegovy's UK licence. You can read the full paper via the STEP 1 publication in the New England Journal of Medicine.

In April 2026, the MHRA approved a dedicated 7.2 mg single-dose Wegovy pen (one pre-set injection per week) for adults with a BMI of 30 or above. Trials at this higher dose reported an average weight reduction of around 20.7% over 72 weeks, which narrows the gap with tirzepatide 15 mg in comparable studies, and the commercial story behind that growth is covered in detail on our page about Novo Nordisk's Wegovy sales figures and market trajectory. The starting dose remains 0.25 mg; a prescriber titrates upward roughly every four weeks. The 7.2 mg pen is a maximum, not a starting point, and whether a specific dose or pen format is available for you is confirmed during a clinical consultation.

If you're curious whether temporary weight gain can happen during treatment, there's a dedicated page that addresses that question honestly. It's more common a concern than many people realise.

Who Wegovy is licensed for and what the prescriber looks at

In the UK, Wegovy holds a licence for adults with a BMI of 30 or above, or a BMI of 27 to 29.9 alongside at least one weight-related health condition such as high blood pressure, high cholesterol, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance, your prescriber will take that into account.

NICE recommends semaglutide (TA875) for use in specialist weight management services, for a maximum of two years, in adults meeting the BMI thresholds above alongside at least one weight-related condition. NHS waiting lists for that route can be lengthy. A private prescription from a regulated online pharmacy is the alternative for people who don't meet the current NHS criteria or prefer not to wait, provided a prescriber judges them clinically suitable after a thorough assessment.

Wegovy is not recommended during pregnancy, while breastfeeding, or when trying to conceive. It is not licensed for anyone under 18. People with a personal or family history of medullary thyroid carcinoma, or with certain pancreatic or gastrointestinal conditions, will need to discuss those details with a prescriber before starting. The NICE appraisal of Wegovy (TA875) sets out the clinical criteria in full.

Side effects and one practical note about contraception

The most common side effects of Wegovy are gastrointestinal: nausea, loose stools, constipation, indigestion and burping are all reported, particularly in the first weeks of treatment or after a dose step-up. For most people they ease off as the body adjusts. Fatigue, headache and injection-site reactions are also noted in the prescribing information.

Rarer but serious: acute pancreatitis is a known, infrequent risk with GLP-1 medicines. Severe stomach pain that reaches through to your back, with or without vomiting, needs prompt medical attention rather than waiting to see if it passes. The MHRA highlighted this in a 2026 Drug Safety Update. Suspect side effects can be reported through the MHRA Yellow Card scheme.

One practical point that surprises some people: NHS guidance notes that women on oral contraceptives do not have the same evidence of reduced pill effectiveness with semaglutide that exists for tirzepatide, but it's still worth raising with your prescriber or GP to make sure your contraception is appropriate while on treatment. That's a question our prescribers hear regularly, and there's a straightforward answer for most situations.

If after reading all of this you'd like to talk through whether Wegovy might be appropriate for you, a free consultation with our prescribers is the right next step. You can also read more about Wegovy's full treatment overview on our dedicated page, or explore the range of treatment options we support.