The active substance in Wegovy, and what it actually does

The biggest misconception: Ozempic and Wegovy are the same thing

A lot of people arrive at this question carrying a reasonable but muddled assumption, that Wegovy is simply a renamed Ozempic, or that the two products are interchangeable for weight loss. It's worth letting that one go gently, because the distinction matters legally and clinically.

Both medicines contain semaglutide. The molecule itself is identical. What differs is the licensed indication, the approved dose, and the regulatory pathway. Ozempic is licensed in the UK for type 2 diabetes. Wegovy is licensed for weight management. Prescribing Ozempic for weight loss would be off-label use, and NHS guidance on semaglutide is clear that these are distinct products with different approved uses. When you read about shortages, media stories often conflate the two, the weight-management indication is Wegovy's, full stop.

The dose difference reinforces this. Ozempic tops out at 1mg or 2mg for diabetes management. Wegovy's standard maintenance dose is 2.4mg weekly, with the newer 7.2mg single-dose pen approved by the MHRA in April 2026 for adults with a BMI of 30 or above. Higher doses, longer titration ladders, and a distinct clinical context make these separate medicines in practice as well as on paper. If you have been wondering whether Wegovy is a controlled substance under UK law, its regulatory classification is another area where it differs from what many people assume.

How semaglutide produces its effects in the body

GLP-1 (glucagon-like peptide-1) is a hormone released from cells in the gut wall after you eat. It does several things: it tells the pancreas to release insulin in response to glucose, it signals the hypothalamus to reduce hunger, and it slows gastric emptying so food leaves your stomach more gradually. The effect is a feeling of fullness that lingers longer than a meal alone would produce.

Semaglutide is a structural analogue of GLP-1, engineered to resist the enzyme that breaks natural GLP-1 down within minutes. That resistance gives semaglutide a half-life long enough for once-weekly dosing, a practical advantage over earlier daily GLP-1 injections like liraglutide. The result is a sustained but not constant activation of GLP-1 receptors in the brain and gut throughout the week.

This is a single-receptor medicine. Wegovy works the GLP-1 pathway only. More on how semaglutide compares across its different formulations is worth reading if you want to understand where Wegovy sits relative to newer dual-agonist options. For the STEP 1 trial evidence (68 weeks, 2.4mg semaglutide, around 15% average body-weight reduction) the original STEP 1 paper in the New England Journal of Medicine is the primary source.

Who the UK licence covers, and what the prescription process involves

Wegovy is licensed for adults with a BMI of 30 or above, or a BMI of 27 to 29.9 alongside 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 guidance. The 7.2mg pen, approved in April 2026, currently carries a BMI-of-30-or-above requirement and is not indicated for the cardiovascular-risk reduction licence.

None of this maps automatically to an approval. A prescriber assesses the whole clinical picture (medical history, current medicines, any contraindications, and your goals) before issuing a prescription. A fuller treatment overview for Wegovy covers eligibility in more depth. Pregnancy, breastfeeding, and trying to conceive are situations where Wegovy is not recommended; anyone under 18 is outside the licensed population.

If you're considering whether a GLP-1 medicine might suit you, it's also worth knowing that tirzepatide (Mounjaro) works across two receptor pathways. Exploring what alternatives exist can help frame the question you bring to a prescriber. That said, which medicine is appropriate isn't something a webpage decides, it's the job of a clinical assessment.

Getting Wegovy legally and safely in the UK

As a prescription-only medicine, Wegovy can only be supplied following a clinical consultation with a qualified prescriber. The MHRA has issued multiple warnings about semaglutide pens sold online without any clinical assessment, large seizures of fake pens, some containing entirely different substances, have occurred. Verifying that an online pharmacy is registered on the GPhC's public register is a straightforward and important step before ordering anything. Sellers offering these medicines at prices far below the market, or without a clear prescription process, are a serious red flag.

nume is a GPhC-registered pharmacy (registration number 9012878) and all consultations are reviewed the same day by a GPhC-registered Independent Prescriber. Where to buy Wegovy safely in the UK covers the verification process in full. For a sense of what treatment costs involve and what an all-inclusive private price typically covers, information on Wegovy pricing and support is a useful starting point. If you have questions our team hasn't answered, our FAQs cover the most common ones. When you're ready to speak to a prescriber, start your free consultation and a real clinician will review your answers the same day.