What Wegovy Contains — and Why the Active Ingredient Matters

You've seen 'semaglutide' on the label, here's what that actually means

Picture reading the box before your first injection. The brand name is Wegovy; the active ingredient listed underneath is semaglutide. For a lot of people, that second word raises more questions than it answers. Semaglutide is a synthetic version of a hormone your gut already produces naturally, called glucagon-like peptide-1, or GLP-1. After you eat, your body releases GLP-1 to signal fullness to the brain, slow the passage of food through the stomach and nudge the pancreas to manage blood sugar. Semaglutide mimics that signal, but with one important difference: your natural GLP-1 breaks down within minutes, while semaglutide is designed to stay active for roughly a week, which is why one injection covers seven days.

As a GLP-1 receptor agonist, semaglutide binds to GLP-1 receptors throughout the body, in the hypothalamus, in the stomach wall, in the gut. The combined effect is a reduced sense of hunger between meals, a longer-lasting feeling of fullness after eating and, over time, a lower overall calorie intake without the white-knuckle effort of conventional dieting. The NHS patient information for semaglutide describes the mechanism clearly if you'd like more detail.

The other ingredients in each Wegovy pen (the excipients) include disodium phosphate dihydrate, propylene glycol and water for injections, among others, and if you want a full breakdown, our page on what Wegovy contains lists every component alongside its purpose. They keep the solution stable and at the right pH. None of them are active; they don't add to or reduce the treatment effect, but they do matter if you have a known allergy to any component, which is something to raise with your prescriber.

The injection pen versus the tablet, same ingredient, different formulation

Wegovy launched in the UK as a once-weekly subcutaneous injection, with dose strengths running from 0.25 mg up to a 2.4 mg maintenance dose and, since early 2026, a 7.2 mg option for eligible patients. In June 2026 the MHRA approved Wegovy tablets, making the UK the first country in Europe to licence an oral GLP-1 medicine for weight management. Both forms contain semaglutide, that part is the same. The difference lies in how the body absorbs it.

Injected semaglutide passes directly into the tissue beneath the skin and from there into the bloodstream. The tablet version faces a harder route: the gut naturally breaks down proteins before they can be absorbed, so the Wegovy pill includes sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (known as SNAC) an absorption enhancer that briefly raises the local pH in the stomach lining and allows semaglutide to cross into the bloodstream. Without SNAC, swallowing semaglutide would be about as effective as swallowing water. The tablet is taken first thing in the morning on an empty stomach with a small sip of plain water, and nothing else (no coffee, no food, no other medicines) for at least 30 minutes afterwards. That wait isn't optional; it's what gives the SNAC enough time to do its job. You can read more about the full tablet presentation on our Wegovy overview page.

The trial evidence for the tablet (the OASIS 4 study, 307 adults, 64 weeks) showed an average weight reduction of around 13.6% compared with 2.4% for placebo, and among participants who took every dose as directed, the average was closer to 17%. The injection's STEP 1 trial reported around 15% average reduction over 68 weeks at the 2.4 mg dose, as published in the New England Journal of Medicine. These are population averages from controlled trials; individual results differ, and a prescriber is the right person to talk through what is realistic for you.

Why semaglutide appears under different brand names, and why that matters

This is where things get genuinely confusing, and it's one of the questions our prescribers hear regularly. Semaglutide is sold under more than one brand name in the UK, and the distinction is important rather than cosmetic. Ozempic also contains semaglutide, but its licence is for type 2 diabetes management, not weight loss. Rybelsus contains oral semaglutide (3 mg, 7 mg and 14 mg tablets) and is also licensed only for type 2 diabetes. Wegovy (injection and tablet) is the formulation licensed specifically for weight management in adults.

This matters legally and clinically. In the UK, prescribing a medicine outside its licensed indication requires a specific clinical justification and a different prescribing process. Any online service offering Ozempic or Rybelsus for weight loss without that framework should prompt caution. If you are trying to understand which products and medicines actually contain semaglutide, that page sets out the landscape clearly.

It is also worth knowing that semaglutide is not the only licensed option for weight management in the UK. Tirzepatide (Mounjaro) activates both GLP-1 and GIP receptors, a different mechanism that produced greater average weight loss in a direct head-to-head trial. Which is more suitable depends on your health history, your starting dose, and clinical factors your prescriber will weigh up. If you are weighing your options, our weight-loss treatment overview covers both and helps frame the conversation.

What this means if you are considering Wegovy through a private pharmacy

Understanding what Wegovy contains is more than academic if you are thinking about starting treatment. It shapes the practical questions worth asking: whether any of the excipients conflict with conditions you have, whether the injection or tablet suits your routine better, and how the dose schedule will be managed over time. It is honest to acknowledge that navigating prescription weight-loss medicines online can feel overwhelming, especially with so many services and so much noise about which is right.

Wegovy is a prescription-only medicine, which means a prescriber must assess your medical history, current medicines and eligibility before it can be issued. The NICE recommendation for semaglutide (TA875) sets out the clinical thresholds; private prescribing sits alongside that framework, with its own eligibility criteria per the licensed SmPC. At nume, every consultation is read by a GPhC-registered prescriber on the day it arrives, a real clinician, not automated software. For context on what treatment costs through a private service, our Wegovy pricing page explains what a legitimate private prescription typically includes. When you feel ready to take the next step, you can check your eligibility by starting a free consultation.