Semaglutide concentration: what the numbers on your Wegovy pen actually mean

You're holding two different pens and wondering why the label reads the same concentration

Picture this: your 0.5 mg Wegovy pen arrives alongside a friend's 1.7 mg pen. You both notice the same figure (1.34 mg/ml) printed on the label. That's not a misprint. Wegovy is manufactured at a single, fixed semaglutide concentration throughout the entire dose range. The device simply releases more solution as the pen strength increases. So the 0.5 mg pen injects roughly 0.37 ml, while the 1.7 mg pen injects about 1.27 ml. Same concentration, different volume.

This is standard pharmaceutical practice for injectable medicines: a consistent concentration makes manufacturing tighter and reduces the risk of confusion during production. For you, it means the number to pay attention to on the label is the dose in milligrams, not the concentration figure. Your prescriber prescribes the dose; the pen handles the volume maths. The preparation steps for your pen are worth reviewing each time you move to a new strength, since the visual fill level in the window will look different.

According to the NHS medicines page for semaglutide, each strength comes in its own colour-coded pen precisely to reduce the chance of selecting the wrong one. If anything on your packaging looks inconsistent with what your pharmacy sent, contact your prescriber before injecting.

The titration ladder and why concentration stays fixed while your dose climbs

Wegovy's licensed schedule starts at 0.25 mg weekly. That first pen is a tolerability step, its job is to let your body adjust to semaglutide before the dose climbs. Most people stay at each level for roughly four weeks before moving up, though the pace is set by your prescriber, not by a calendar. The full ladder runs 0.25 mg, 0.5 mg, 1.0 mg, 1.7 mg, and then the 2.4 mg maintenance dose.

Since April 2026, a dedicated 7.2 mg single-dose pen has also been MHRA-approved for adults with obesity (BMI 30 or above). The MHRA's announcement of the 7.2 mg pen approval confirms it uses the same semaglutide concentration (1.34 mg/ml) with a correspondingly larger delivery volume. Titration to reach 7.2 mg still starts at 0.25 mg; jumping straight to the highest pen is not part of the licensed approach.

If you want to see exactly how an injection is done before you start, our semaglutide administration video walks you through each step, including which injection sites are suitable, and our guide to semaglutide route of administration explains the reasoning behind subcutaneous delivery and what that means in practice. The concentration figure won't change as you move up the ladder, but your injection technique still matters at every step.

Why concentration matters when buying semaglutide, and the counterfeit problem

Here is where the concentration number becomes a genuine safety issue rather than a label curiosity. Semaglutide is a prescription-only medicine. Sellers operating without a proper supply chain and clinical oversight have no reliable way to guarantee that the medicine inside a pen matches the stated concentration. The MHRA has warned publicly about counterfeit weight-loss pens seized in the UK, some contained insulin instead of semaglutide, which can cause a dangerous drop in blood sugar. A pen labelled 1.34 mg/ml that actually contains something else, or the right molecule at the wrong concentration, is not a minor discrepancy.

The only way to be confident about what you're injecting is to source your prescription through a pharmacy you can verify on the GPhC register. If a seller offers semaglutide without a clinical assessment, or at prices that seem implausibly low, that is a warning sign worth acting on. You can check any online pharmacy's registration at the GPhC's online pharmacy register. For context on how nume handles supply, our about us page covers the licensed UK supply chain we use.

If you have a concern about a product you've already received (whether from us or elsewhere) our contact and aftercare team is available seven days a week. If you'd like a broader overview of the most common semaglutide concerns patients raise, including questions about sourcing and side effects, that page brings the key points together. Reporting suspected counterfeit products through the MHRA's Yellow Card scheme also helps the regulator track problems.

Worth noting: if your delivery is timed around a bank holiday or you've ordered just after payday in a busy month, DPD tracking will tell you exactly where your pen is, the packaging itself is plain and unbranded.

Oral semaglutide and concentration, a different picture entirely

Wegovy is also now available as a tablet, approved by the MHRA in June 2026 as the first oral GLP-1 medicine licensed in the UK for weight management. Oral semaglutide works very differently from the injection: it is co-formulated with an absorption enhancer (SNAC) that allows the molecule to cross the gut wall. The concept of milligrams per millilitre does not apply to a tablet in the same way, each tablet contains a fixed milligram amount of semaglutide, not a concentration in solution.

The oral dose schedule is 1.5 mg daily, escalating through 4 mg and 9 mg to a 25 mg maintenance dose. Because absorption from the gut is far lower than from a subcutaneous injection, the tablet doses appear much higher than the injection doses, but this reflects the different delivery route, not a stronger medicine. Tablet strength and injection strength are not directly comparable. Our page on what semaglutide is mixed with goes into the formulation detail, including how the SNAC absorption enhancer works.

Whether injection or tablet is the right route for a given patient is a clinical decision. If you'd like to read a full overview of how semaglutide works and what the treatment involves before deciding, that's a good place to start, or you can move straight to a free consultation with our prescribers.