Wegovy as a weight loss drug: the complete UK picture

How does Wegovy actually produce weight loss?

Semaglutide mimics a gut hormone called GLP-1 (glucagon-like peptide-1) that your body releases after eating. By binding to GLP-1 receptors in the brain and gut, it quiets the appetite signals that normally drive hunger between meals and slows the rate at which the stomach empties. Most people find they feel full sooner and are less preoccupied with food generally. That shift in biology, maintained week after week, is what underpins the weight loss seen in trials.

It is worth being clear about what semaglutide is not doing: it is not blocking fat absorption (that is orlistat's mechanism), and it is not a stimulant. The effect is quieter than that. People on treatment often describe simply eating less without it feeling like willpower. The semaglutide overview on our site goes into the mechanism in more depth if you want the biochemistry.

Wegovy is injected once a week into the abdomen, thigh or upper arm, using a pre-filled pen. The dose starts at 0.25 mg to let the body adjust, then increases roughly every four weeks under prescriber guidance, moving through 0.5 mg, 1.0 mg and 1.7 mg before reaching the 2.4 mg maintenance dose. In January 2026, the MHRA approved a 7.2 mg maintenance dose as well, with a dedicated single-dose pen approved in April 2026 for adults with a BMI of 30 or above. The Wegovy treatment page has more on what the current dose options look like in practice.

Who is this weight loss drug approved for in the UK?

The UK licence covers adults with a BMI of 30 or above, or a BMI of 27 to 29.9 if they have at least one weight-related condition, such as high blood pressure, type 2 diabetes, high cholesterol or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. Wegovy is not licensed for anyone under 18, and it is not recommended during pregnancy, breastfeeding or when trying to conceive.

NICE guidance (TA875) sets out specific NHS eligibility criteria: access is through specialist weight management services, carries a two-year maximum treatment period under NHS commissioning, and requires at least one weight-related comorbidity alongside a BMI of 35 or above (with lower thresholds for certain ethnic backgrounds). Private routes have different criteria — those set out in the product licence — and a prescriber will assess your full clinical picture regardless of which route you take. If you want to compare options before committing, our page on medicines similar to Wegovy sets out the landscape clearly.

One thing the prescriber always considers: a weight-related condition diagnosed and being managed changes the picture compared with BMI alone. The numbers are a starting point, not the whole conversation. More on Wegovy and weight loss eligibility is covered here.

What do side effects and safety monitoring look like?

The most common side effects of Wegovy as a weight loss drug are gastrointestinal: nausea, diarrhoea, constipation, indigestion and vomiting appear most often when starting treatment or moving up a dose, and they typically ease within a couple of weeks. Fatigue, headache, dizziness and injection-site reactions are also reported. The NHS semaglutide medicines page lists these clearly and is worth bookmarking.

Serious side effects are less common but matter. Acute pancreatitis is a known risk: the MHRA highlighted this in a Drug Safety Update in January 2026, noting that severe, persistent stomach pain (especially if it radiates toward the back) needs urgent medical attention. Gallbladder problems have also been reported. Anyone on treatment is encouraged to report unexpected symptoms through the MHRA Yellow Card scheme, which helps regulators spot emerging safety signals.

Because Wegovy carries the Black Triangle designation, there is additional post-market surveillance running alongside the usual pharmacovigilance. That is a standard feature of newer medicines, not a reason for alarm. Prescribers working in this area follow it closely, and a question our clinical team hears regularly is whether that symbol signals something to worry about, it does not; it simply means regulators want more data collected, which is routine for a medicine of this age.

Is the NHS prescribing Wegovy for weight loss, and what is the private alternative?

NHS access to Wegovy exists but is limited by specialist service availability and strict eligibility criteria under NICE TA875. Waiting lists for NHS specialist weight management services can be long, and the two-year treatment cap adds a further consideration. For a full breakdown of the NHS versus private landscape for this class of medicines, our Wegovy weight loss drugs guide is a practical place to start.

Private prescribing removes the waiting list and the specialist-service requirement, but the clinical rigour should be identical. Any legitimate private route requires a proper clinical assessment, not a tick-box questionnaire processed by software. You should also be able to verify the pharmacy dispensing your medicine on the GPhC register at pharmacyregulation.org/registers. If a seller cannot be found there, that is a serious warning sign.

On cost, private Wegovy pricing varies by dose and provider. If the question of what you should expect to pay is on your mind, our honest guide to Wegovy costs in the UK covers the market context without padding. At nume, one transparent price covers the clinical consultation, prescription, treatment and free next-working-day delivery, when your order is dispatched, you get a DPD tracking link and a plain, unmarked box arrives the following working day. There are no subscriptions and no hidden fees; every repeat order is reviewed by a prescriber before anything is sent. If you want to understand the broader options available, our weight loss treatment overview is a good starting point.