The Novo Nordisk weight loss injection: what the evidence actually says

What the STEP 1 trial data tells us, and what it doesn't

The headline figure most people encounter is 15%. In the STEP 1 study, adults living with obesity who received semaglutide 2.4mg weekly lost an average of roughly 15% of their body weight over 68 weeks, compared with about 2.4% in the placebo group. That is a meaningful difference, and it is why NICE recommended Wegovy for eligible adults on the NHS under technology appraisal TA875.

One misconception is worth clearing up gently: some people assume that a 15% average means everyone on the injection loses exactly that much. Clinical trials report averages across thousands of participants; individual results spread widely around that figure depending on starting weight, adherence, dietary changes, and other health factors. The clinical evidence is genuinely strong, but "average" means some people lose more and some lose less. A prescriber can give you a more grounded picture during your assessment.

In April 2026 the MHRA approved a dedicated 7.2mg single-dose Wegovy pen, and trials at that higher maintenance dose reported average weight loss of around 20.7% over 72 weeks, narrowing the gap with tirzepatide. Whether the 7.2mg dose is appropriate for a particular patient is a clinical decision, not a default.

Wegovy vs Ozempic: why the brand name printed on the pen matters

Both Wegovy and Ozempic contain semaglutide, made by Novo Nordisk. The difference is their licensed indications. Ozempic holds a UK authorisation for type 2 diabetes management. Wegovy holds a UK authorisation for weight management in adults with a BMI of 30 or above, or 27 and above with at least one weight-related condition such as high blood pressure or high cholesterol.

Prescribing Ozempic for weight loss would be an off-label use; it is not what the medicine is licensed for in the UK, and the NHS medicines information for semaglutide makes the distinction clear. This is not a technicality. Licensed use means the dose, the formulation, the trial evidence, and the regulatory oversight all align with the purpose you are taking it for.

If you are researching how weight loss injections work more broadly, Wegovy and Mounjaro (tirzepatide, made by Eli Lilly) are the two medicines licensed and dispensed in the UK specifically for weight management in adults.

What the weekly injection routine looks like

Wegovy comes as a pre-filled injection pen. You inject it once a week into the abdomen, thigh, or upper arm, rotating the site each time. The starting dose is 0.25mg, not because it is therapeutic at that level, but because the gradual titration (moving up roughly every four weeks through 0.5mg, 1.0mg, 1.7mg, 2.4mg, and potentially to 7.2mg) gives the body time to adjust and reduces early gastrointestinal side effects.

The pen must be stored in a refrigerator between 2°C and 8°C; for exact guidance on short room-temperature windows during travel or daily use, the Patient Information Leaflet and SmPC are the authoritative sources. Side effects are predominantly gastrointestinal: nausea, diarrhoea, constipation, and indigestion are the most commonly reported, and they tend to be most noticeable when starting or stepping up a dose, settling over the following days to weeks for most people. A separate page covers injection complications and side effects in more detail, including when to contact a doctor promptly.

If needles are a concern, it is worth knowing that Novo Nordisk's pen design uses a fine gauge needle and an auto-injection mechanism on some formats. The Novo Nordisk injection pen page walks through the device in more detail. For people who would prefer to avoid injections entirely, an oral alternative now exists: the non-injection weight loss options page covers the recently approved Wegovy tablet and other choices.

Getting a legitimate Wegovy prescription in the UK

Wegovy is a prescription-only medicine. The only lawful route is a prescription issued following a proper clinical assessment by a registered prescriber. That assessment considers your BMI, your weight-related health conditions, your medical history, and any medicines you take that might interact, including oral contraceptives, where guidance from NHS England recommends considering transdermal HRT and adding a non-oral contraceptive method for the first four weeks of semaglutide treatment where relevant.

For context on private costs, the weight loss injection pricing page explains what private treatment typically includes and what legitimate prices reflect. A sharp price discount or a seller offering these medicines without a prescription should be treated as a warning sign, not a bargain; the MHRA has warned publicly about fake pens and taken enforcement action against illicit supply chains. You can check any online pharmacy on the GPhC register at pharmacyregulation.org.

At nume, every consultation is read by a GPhC-registered Independent Prescriber, a real clinician, not a decision tree. If you are clinically suitable, treatment is dispatched the same day for free next-working-day delivery. Check your eligibility by starting a free consultation on our weight loss treatments page.