What Does 30 Units of Semaglutide Actually Mean?

Why does '30 units of semaglutide' come up at all?

A question our prescribers hear most weeks is some version of: "I've seen semaglutide measured in units online, is 30 units the right amount for me?" The short answer is that this framing doesn't apply to any UK-licensed semaglutide product for weight loss.

The unit system is familiar from insulin: insulin is standardised at 100 units per millilitre, so drawing 30 units from a vial gives you 0.3ml. Some people try to apply the same logic to semaglutide when they encounter unlicensed or compounded preparations sold online, often in small vials with reconstitution instructions. That is a genuinely different product from Wegovy.

Wegovy comes as a factory-sealed, pre-filled pen. You dial the pen, you inject, there is no vial, no syringe, no unit calculation. The dose steps are 0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg (rising to 7.2mg with the newer single-dose pen approved by the MHRA in April 2026). Milligrams are the unit of measure throughout. If something is described to you in units, it is describing a different preparation entirely.

The ml-to-units conversion guide on this site explains the arithmetic in more detail, and makes clear why that arithmetic belongs to an entirely separate context from licensed treatment.

Is a syringe-drawn preparation of semaglutide safe to use?

This is where the distinction becomes more than academic. The MHRA has issued repeated warnings about unlicensed semaglutide preparations circulating in the UK, including products sold online that require reconstitution and syringe drawing. These are not the same as Wegovy. They have not gone through the same regulatory scrutiny for purity, potency or sterility.

The risks are layered. Dose accuracy is one: semaglutide is active in the microgram-to-milligram range, and a small drawing error with a syringe is meaningful. Contamination is another. And the concentration may not be standardised in the way insulin is, so "30 units" could correspond to wildly different amounts of active drug depending on whose vial you're holding.

The MHRA's public guidance on GLP-1 medicines for weight loss makes the position clear: these are prescription-only medicines and should only be obtained through a registered pharmacy following a clinical assessment. You can report suspect sellers or products at the MHRA's Yellow Card scheme, which also accepts reports of adverse reactions.

If you want to understand what the licensed schedule actually looks like, the Wegovy overview page covers the approved dose steps and what each one is designed to do.

What dose of semaglutide is actually used in licensed weight-loss treatment?

Under the Wegovy licence, treatment begins at 0.25mg once weekly, a starting point designed to let the body adjust rather than to produce immediate weight loss. The prescriber then increases the dose in steps, typically every four weeks, through 0.5mg, 1mg and 1.7mg, up to a maintenance dose of 2.4mg. The newer 7.2mg pen, approved for adults with a BMI of 30 or above, extends that ceiling further for those who need it.

None of these steps are expressed in units. None involve a syringe drawn from a vial. Each pen contains the right amount of medicine for the right dose step, pre-set and ready to inject.

Clinical trial evidence published in the New England Journal of Medicine (STEP 1) showed an average body-weight reduction of around 15% over 68 weeks at the 2.4mg maintenance dose, alongside a reduced-calorie diet and increased activity. Those results are for the licensed product, used at licensed doses decided by a prescriber.

If you're trying to work out whether you might be eligible for Wegovy, the weight-loss treatment overview is a useful starting point, and there's more detail on the 10 units semaglutide page about how this conversion question arises at different points in the dose ladder, including at the lower end where our 15 units semaglutide guide picks up the same thread for people who have seen that figure quoted instead.

So what should someone do if they've been using a unit-based preparation?

Tell your GP or a prescribing pharmacist, and stop using the unlicensed product. This isn't a lecture, it's practical. If you've been taking an unlicensed preparation for some weeks and want to switch to a licensed medicine, a prescriber needs to know what you've been taking and at what frequency before they can assess you safely. Semaglutide has a long half-life; the timing of any switch matters clinically.

For context on what the cost of licensed treatment actually looks like (and why the price of unlicensed vials sometimes looks attractive by comparison) the Wegovy prices page sets out what legitimate private treatment includes. It's worth reading alongside this page.

If you'd like to check whether licensed semaglutide treatment is appropriate for your situation, nume offers a free consultation reviewed by a GPhC-registered prescriber, a real clinician reads your answers the same day, not software. That review is the right place to start. The full semaglutide information page covers the broader picture if you want to read further first.