How to use a Wegovy 4-dose pen: step-by-step instructions

Your pen has arrived, what you're actually looking at

Picture this: you've just opened a plain, unbranded box from the courier. Inside is a Wegovy pen, a small package of needles, and a Patient Information Leaflet. The pen itself looks a little like a thick marker, a coloured label showing your dose strength, a dose counter window on the side, and a grey needle cap at the top. That counter is your four-week tracker; it steps down from 4 to 1 each time you inject, then shows a final symbol when the pen is empty.

Before anything else, check the medicine through the window in the pen body. It should be clear, colourless, and free from visible particles. If it looks cloudy, discoloured, or you can see floating material, do not inject, contact your prescribing team or the support team at our pharmacy. Also check the expiry date printed on the label. Store your pen in the fridge at 2–8°C; exact guidance on the room-temperature window you are allowed before injection is in your Patient Information Leaflet, and it is worth reading that section carefully before your first use.

A question our prescribers hear most weeks: "Can I use any needle, or does it have to be specific ones?" The pen is designed for compatible pen needles, check the Patient Information Leaflet for the gauge and length recommended for this device, and change to a fresh needle before every injection. Reusing a needle risks a blocked tip, inaccurate dosing, and unnecessary discomfort.

Injecting: the sequence that makes it reliable

Choose your injection site first. The abdomen (keeping clear of the navel by a few centimetres), the front of the thigh, and the outer upper arm all work well. Pick a spot you have not used recently, and clean it with an alcohol swab if your clinical team has advised this. Let the skin dry before injecting.

Attach a new needle to the pen, remove both needle caps, and carry out the flow check your Patient Information Leaflet describes before your very first injection from a new pen, this confirms the device is primed and working. If you are on your starting strength, our Wegovy 0.25 instructions page walks through this flow check and the full first-use sequence in detail. Hold the pen firmly, press the needle against the skin at a 90-degree angle, press the injection button, and keep holding it there. The full dose takes a few seconds to deliver; releasing too early can mean a partial dose. When you lift the pen away, the needle retracts automatically.

You can read more about the full Wegovy dosage and injection guidance on a dedicated page if you want a broader overview of the titration schedule alongside technique. After injecting, place the outer needle cap back on, unscrew the needle, and dispose of it in a sharps container, not your kitchen bin. The pen itself goes in the sharps bin once it is empty.

Managing the four weeks: what changes and what doesn't

Each dose in the pen is fixed at the strength your prescriber has set, 0.25mg, 0.5mg, 1.0mg, 1.7mg, or 2.4mg depending on where you are in the titration schedule. Nothing inside the pen changes between doses; you simply repeat the injection on the same day each week. Choosing a consistent day (Sunday evening, say, or Monday morning) helps build the habit.

If a dose is late by a day or two, your missed-dose guidance page walks through what to do depending on how much time has passed. A straightforward rule: if the next scheduled dose is fewer than two days away, skip the missed one and continue as normal; if it is further away, take it as soon as you remember. These are general pointers, not a substitute for your prescriber's advice.

The full range of Wegovy dose strengths is explained elsewhere if you want context on where your current pen sits in the overall journey. Side effects, particularly nausea, are most noticeable after starting or moving to a higher strength, and they tend to settle within a week or two for most people. The NHS semaglutide medicines page lists common and less common effects clearly and is worth bookmarking.

When to pause, call for help, or speak to your prescriber

Most people get through their first four-week pen without anything beyond mild nausea or a little redness at the injection site. Occasionally something more significant happens, and knowing which symptoms need prompt attention matters.

Contact a GP or go to urgent care if you develop severe stomach pain that spreads to your back, with or without vomiting, this can be a sign of pancreatitis, which the MHRA flagged as an infrequent but serious risk in its January 2026 Drug Safety Update on GLP-1 medicines. Signs of a serious allergic reaction (swelling of the face, lips or throat, difficulty breathing, rapid heartbeat) also need immediate attention.

For questions about how your pen is behaving (unexpected leakage, a stuck button, a counter that hasn't moved) reach out to your prescribing pharmacy rather than trying to investigate the device yourself. You can explore the broader Wegovy pen and dose format topic if you are unsure whether your pen type matches your current strength, and the general FAQs cover a range of practical questions our patients ask regularly. If you are considering starting treatment and would like a clinical assessment, checking your eligibility through our free consultation is the natural next step.