What Wegovy contains — and why the active ingredient matters

The misconception worth clearing up first: Wegovy and Ozempic are not the same product

A lot of people arrive at this question having already seen semaglutide mentioned in two different contexts. There's a persistent idea that Wegovy and Ozempic are interchangeable, or that Ozempic is just a cheaper version of the same thing. It isn't. Both contain semaglutide, yes, but Ozempic is licensed in the UK for type 2 diabetes, not for weight management. Wegovy holds a separate UK licence specifically for weight loss, at a higher maintenance dose. The MHRA has been clear that prescribing Ozempic for weight loss is an off-label use, and that GLP-1 medicines should not be sought for cosmetic purposes. So when someone asks what Wegovy contains, the short answer is semaglutide, but understanding which product contains it at which dose and for which licence is the part that gets blurred online. Once that's clear, the rest makes more sense.

The semaglutide molecule itself is a 94% match to naturally occurring human GLP-1, modified to extend its half-life so a once-weekly injection is sufficient. That structural tweak is what separates it from the endogenous hormone, which clears the body within minutes.

What the active ingredient semaglutide actually does in the body

Semaglutide binds to GLP-1 receptors in several places: the gut, the pancreas and the brain. In the hypothalamus (the part of the brain that regulates appetite) this binding reduces hunger signals. In the gut, it slows gastric emptying, so food stays in the stomach longer and the feeling of fullness lasts. In the pancreas it supports insulin release in response to meals, which is relevant for people with type 2 diabetes but also contributes to stable blood sugar in people without it.

The result, in practice, is that people on Wegovy tend to feel satisfied with smaller portions and experience fewer cravings. The Wegovy overview covers this in more depth, but from a purely ingredient standpoint: it is semaglutide doing all of that work, not a combination of agents. The GLP-1 classification explains the receptor pathway in plain terms if the mechanism interests you further. Clinical trial data, published in the New England Journal of Medicine as part of the STEP programme, recorded an average weight reduction of around 15% over 68 weeks at the 2.4 mg maintenance dose, a figure the NHS semaglutide page also references for context.

The inactive ingredients and what they're for

Beyond semaglutide, the Wegovy injection solution contains a small number of excipients whose job is to keep the active molecule stable and the solution injectable. These include disodium phosphate dihydrate (a buffer that holds the pH at a level semaglutide tolerates), propylene glycol (a solvent that aids stability), phenol (a preservative), and water for injections as the base. The full list, along with exact quantities, is published in the Wegovy SmPC on the electronic Medicines Compendium (eMC), which is the authoritative reference if you have an allergy concern or want to check a specific excipient. The Patient Information Leaflet inside the box carries the same list in plain language.

People sometimes worry about the inactive ingredients, and that worry is fair, especially if you have a known sensitivity. If phenol or propylene glycol is a concern, that's exactly the kind of thing to raise when you speak to a prescriber, before any treatment starts. None of the standard excipients in Wegovy are obscure, but a clinician should know about relevant sensitivities all the same.

How the licence and dose range fit together

Wegovy is licensed in the UK for adults with a BMI of 30 or above, or 27 or above alongside a weight-related condition such as hypertension, high cholesterol or obstructive sleep apnoea. The treatment starts at 0.25 mg weekly and is titrated by the prescriber over approximately four monthly steps to the 2.4 mg maintenance dose, and as of April 2026, the MHRA has approved a higher 7.2 mg maintenance dose, currently being introduced. NICE's appraisal of semaglutide for weight management, TA875, sets out the criteria for NHS access, which are narrower than the licensed criteria and involve specialist weight management services. Private access through a regulated pharmacy operates on the licensed criteria, subject to individual clinical assessment by a prescriber. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance, a prescriber will confirm whether that affects your own picture.

If you're thinking about whether Wegovy might be suitable, the place to start is a proper consultation rather than working backwards from the ingredient list. Our prescribers review every case the same day it's submitted, a real clinician reads your answers, not an automated system. You can also explore other medicines that contain semaglutide or read about weight-loss treatment options more broadly before you decide. When you're ready, speak to our prescribers, the consultation is free and there's no obligation.