Semaglutide: how many units does each Wegovy dose contain?

You've googled "how many units", here's why that's the wrong question for Wegovy

Picture the scenario: you've used insulin before, or you've seen a friend draw up an injection using a syringe marked in units. When your Wegovy pen arrives (plain packaging, a DPD notification on your phone the morning it's due) you open the box and look for unit markings. There aren't any. That's not an error.

Insulin is concentrated and variable enough that patients need to measure individual doses in international units, using a calibrated syringe or pen dial. Semaglutide (the medicine in Wegovy) is supplied in a completely different delivery system. Each pre-filled Wegovy pen contains a fixed amount of the drug at a fixed concentration for that dose strength. You attach the needle, dial to the single dose mark, inject, and the pen does the rest. The relationship between millilitres and units in semaglutide pens is a common point of confusion, but it's a moot point in practice: there is nothing to measure and nothing to dial in milligrams or units at the point of injection.

If you ever find yourself drawing semaglutide into a separate syringe, that is a serious safety warning sign. The pre-filled pen exists precisely so that doesn't happen. The NHS semaglutide patient information page is clear that the medicine should be used only as supplied.

The dose schedule in milligrams, and why the volume shifts at each step

The licensed Wegovy injection schedule runs: 0.25mg for four weeks, then 0.5mg, 1.0mg, 1.7mg, and finally 2.4mg as the maintenance dose, each step held for approximately four weeks before the prescriber moves you up. From January 2026 a 7.2mg dose is also licensed in the UK following MHRA approval of a dedicated single-dose pen, though the 2.4mg dose remains the most widely used maintenance level.

Here's where the volume question gets interesting. Novo Nordisk formulates each pen strength at a different concentration of semaglutide per millilitre. That means the actual volume injected (in millilitres) is not the same across all dose pens, even though the injection experience feels similar. For anyone who wants to understand the millilitre-to-units conversion logic for semaglutide, the short version is that the numbers don't map neatly onto insulin-unit equivalents, because the concentrations and purposes of the medicines are entirely different.

What you need to know practically: you do not need to calculate anything. The pen is pre-set. Your prescriber sets the dose. Your job is to inject at the right site (abdomen, thigh, or upper arm) rotate those sites, and follow the guidance in your Patient Information Leaflet. Anything beyond that is a clinical conversation, not a calculation.

When people ask about specific unit numbers, 5, 10, 25 units

Search results for semaglutide often include queries like what 5 units of semaglutide looks like, what 10 units corresponds to, or what 25 units means. These questions mostly originate from compounded semaglutide products circulating in other markets, where the medicine is sometimes supplied in a vial with a separate syringe and the concentration varies by compounder. In those cases, a patient might genuinely need to draw up a specific number of units using an insulin syringe.

In the UK, Wegovy is only licensed and available as a pre-filled pen. Compounded semaglutide is not licensed here. If someone offers you semaglutide in a vial without a prescription (via social media, a website with improbably low prices, or any route that doesn't involve a GPhC-registered pharmacy and a clinical assessment) the MHRA has warned clearly that fake and unlicensed injectable weight-loss products have caused serious harm, including hospitalisations.

The cost of Wegovy through a legitimate, clinically supervised service is a common question; the Wegovy pricing page covers what private treatment typically costs and what a legitimate price should include. Knowing what you're paying for is part of knowing you're getting the real thing. If your pen ever arrives warm rather than refrigerator-cold, the guidance on what to do if Wegovy arrives warm applies, another reminder that the supply chain matters.

What semaglutide is actually doing, a brief note for context

Wegovy works as a GLP-1 receptor agonist: it mimics a gut hormone that signals fullness to the brain, slows gastric emptying, and reduces appetite. NICE's recommendation of semaglutide for weight management, documented in NICE technology appraisal TA875, followed evidence from the STEP trials showing roughly 15% average weight reduction over 68 weeks at 2.4mg. That evidence is the basis for the licensed dose schedule, 2.4mg wasn't chosen arbitrarily; it's where the clinical data sits.

None of this changes how many units are in a pen (the answer remains: the question doesn't apply). But it does explain why the titration schedule matters and why rushing through doses (or staying at a lower dose indefinitely) are both things to discuss with a prescriber rather than decide independently. A clinician who knows your health history can assess whether you're responding well, whether side effects need managing, and whether you've reached the right maintenance dose for you.

If you'd like to explore whether Wegovy or another licensed treatment might be appropriate for you, the free consultation at nume is reviewed the same day by a GPhC-registered prescriber, a real clinician, not automated software. There's no obligation, and our clinical team is available seven days a week if questions come up afterwards.