The Wegovy 1ml pen: what you're actually injecting and why it matters

Why 1ml, and what that tells you about how the pen is built

The decision the pen's design makes for you is a simple one: inject or don't. There is no dose to select. Each Wegovy pen holds exactly 1ml of solution and is factory-set to deliver that entire volume in one press. What varies across the five steps of the titration schedule is how much semaglutide is dissolved in that millilitre. At 0.25mg the concentration is low; at 2.4mg it is considerably higher. The liquid volume you feel going in is the same every time.

This matters practically. Some people expect the injection to feel different at a higher dose, or worry they have under-injected if it feels no larger. It won't feel larger. The step-by-step injection guide covers exactly what to expect at each stage, including how to confirm a full dose has been delivered by checking the dose window on the pen body.

The pen itself is slim, pre-assembled and has a hidden, auto-retractable needle. You press it against clean skin, hear a click, hold for roughly ten seconds, and the pen does the rest. A question our prescribers hear most weeks: "Did it actually go in?" The answer is almost always yes, the mechanism is designed so that the needle cannot extend without the dose delivering.

Storage is straightforward: keep unused pens refrigerated between 2°C and 8°C. The Patient Information Leaflet on the electronic Medicines Compendium gives the exact room-temperature window for when a pen is out of the fridge, always check there rather than relying on memory or a third-party source.

Choosing injection sites with a 1ml subcutaneous dose in mind

Subcutaneous means the injection goes into fatty tissue just beneath the skin, not into muscle. With 1ml going in at once, site choice and rotation genuinely affect comfort and absorption consistency. The three licensed sites are the abdomen (at least a few centimetres from the navel), the front of the thigh, and the outer upper arm. Rotating between them (and within each site) prevents localised tissue changes that can slow absorption over time.

Pinching the skin slightly before injecting can help at leaner sites, particularly the thigh. Injecting into cold skin straight from the fridge is a common reason for discomfort; leaving the pen at room temperature for thirty minutes or so before use tends to help. Cleaning the skin first with an alcohol swab and letting it dry fully before pressing the pen in is a small step that reduces the risk of irritation.

Injection-site reactions (redness, mild bruising, a small lump) are listed among the common side effects by the NHS medicines page for semaglutide. They usually settle within a day or two. Persistent swelling, hardening, or signs of infection at a site are worth raising with your prescriber promptly.

If you are curious about how the Wegovy 1ml pen compares to what is available at different volume formats, the overview of Wegovy pen volumes sets out the full picture.

Side effects to be aware of at each dose step

Most side effects from semaglutide are gastrointestinal, and they tend to be most noticeable in the days after starting or stepping up. Nausea is the most reported; diarrhoea, constipation, reflux and stomach discomfort follow. For most people these are mild, manageable, and settle within a couple of weeks as the body adjusts to the new concentration in that 1ml dose.

Eating smaller portions, avoiding fatty or very rich foods during the adjustment period, and staying well hydrated all help. These are not rigid rules; they are what people who get through the early weeks more comfortably tend to do.

There are some symptoms that need prompt medical attention rather than watchful waiting. Severe stomach pain that radiates to the back, with or without vomiting, should be assessed urgently, this is the pattern the MHRA flagged in its January 2026 Drug Safety Update on acute pancreatitis in people taking GLP-1 medicines. Gallbladder symptoms, signs of a serious allergic reaction, or significant dehydration from persistent vomiting all warrant the same response: contact a doctor or call 111. Any suspected side effect can be reported at yellowcard.mhra.gov.uk.

Wegovy is not recommended during pregnancy, while breastfeeding, or when trying to conceive. It is not licensed for anyone under 18. Certain conditions (including a personal or family history of medullary thyroid carcinoma) require specific prescriber discussion before treatment starts.

How cost fits into the decision about starting Wegovy

Private Wegovy treatment in the UK is priced per pen, and the cost changes as your dose steps up through the schedule, with options ranging from the standard Wegovy pen through to the Wegovy 3ml pen used at higher maintenance doses. The Wegovy price comparison page sets out how private costs are structured and what they typically include. A legitimate price covers clinical assessment and prescription; services that separate these out or quote only the medicine itself often present an incomplete picture of what you will actually pay.

At nume, one transparent price covers the consultation, prescription, treatment and free next-working-day delivery. Your pen arrives via DPD in plain, unbranded packaging, nothing on the outside to tell a neighbour what is inside. No subscription is set up on your behalf; every repeat order is reviewed by a prescriber before it goes out.

On the NHS, Wegovy is available through specialist weight management services under NICE guidance, though waiting lists are commonly long. Exploring your treatment options is a useful starting point if you are weighing up the routes available to you. When you are ready, checking your eligibility with our clinical team is free and takes only a few minutes.