How to apply Wegovy: a plain guide to injecting semaglutide safely

Which site to choose, and why rotating actually matters

The three approved injection sites (abdomen, front thigh, outer upper arm) are interchangeable in terms of how semaglutide is absorbed, so the choice is mostly about what is comfortable for you. The abdomen is the most accessible for most people and the easiest to do alone. The thigh works well if you prefer to sit. The upper arm is fine but usually easier with help, since you need a free hand to press the pen.

What matters more than which site you pick today is varying the exact spot within that site week by week. Injecting repeatedly into the same small area can cause the skin to thicken or develop fatty lumps (a process called lipohypertrophy) and medicine absorbs less predictably through those areas. A practical checking habit that takes under a minute: before you inject, run your fingertips lightly over your usual spot. If it feels firmer or lumpier than the surrounding skin, move two to three centimetres away. That small check can make a real difference to how consistently the treatment works.

Keep at least 5 cm from your navel when using the abdomen, and avoid areas that are bruised, sore, or have broken skin. The full step-by-step application guide on this site covers positioning in more detail, including what to do if you cannot comfortably reach the recommended areas.

The injection itself (what each part of the process is actually doing

Wegovy comes as a pre-filled, pre-set pen) you do not dial a dose or draw up a syringe. Each pen contains four weekly doses delivered via an auto-injector mechanism. The sequence is deliberate and there is a reason for every step.

Removing the pen cap and checking the liquid in the window (it should be clear and colourless) takes seconds but matters, if it looks cloudy, discoloured, or contains particles, do not use that pen and contact your prescriber. Let the pen warm gently to room temperature for about 20–30 minutes before injecting; cold liquid from the fridge tends to sting more.

Press the pen firmly against the skin until the needle inserts, then press and hold the button. The six-second hold ensures the full dose has been delivered before you withdraw the pen, releasing too early is the most common cause of a missed partial dose. When you pull the pen away, a safety shield covers the needle automatically. You can confirm the dose was given by checking the dose indicator in the pen window, your video walkthrough of the injection technique shows exactly what a completed dose looks like in the window. The NHS semaglutide medicines page also gives clear guidance on how to use the pen correctly.

Side effects to expect, and the ones that need medical attention

Most people on Wegovy experience some gastrointestinal effects, particularly in the weeks after starting or moving to a higher dose. Nausea is the most reported, followed by loose stools or constipation, indigestion, and occasionally vomiting. For the majority these settle as the body adjusts, often within a week or two of a dose change.

Eating smaller, lower-fat meals and staying well hydrated helps. Injecting at a time of day when you can rest afterwards also makes the early weeks more comfortable, some people find evening injections mean any nausea passes during sleep.

A smaller number of people experience more significant effects. Seek prompt medical attention for severe stomach pain that does not ease, especially if it radiates towards your back, this can indicate pancreatitis, which the MHRA highlighted in a Drug Safety Update in January 2026 as a known but infrequent risk with GLP-1 medicines. Signs of an allergic reaction (swelling of the face or throat, difficulty breathing) also need urgent assessment. If you are noticing side effects that are affecting your quality of life or making it hard to continue, our guide to Wegovy complications covers the full picture, including when to contact your prescriber and when to go to A&E.

If a dose is late, forgotten, or you are thinking about stopping

Life happens, and a missed dose does not mean starting from scratch. The general guidance is to inject as soon as you remember, provided there are at least 72 hours before your next scheduled weekly dose. If the gap is shorter, skip the missed dose and carry on with your normal day. Never take two doses close together.

The cost of treatment is a practical reality, and it is worth knowing what is included before comparing providers. If you have seen lower prices elsewhere and are wondering what is and is not included, the Wegovy cost overview explains how private pricing is structured in the UK and what a legitimate provider's price should cover.

Thinking about stopping altogether is different. Semaglutide is a long-term medicine for a long-term condition, and weight tends to return when treatment stops, not because the person has failed, but because the biological signals that drove appetite return. If Wegovy does not feel like it is working for you, or the side effects are difficult, speak to your prescriber before stopping. There may be practical adjustments that change the picture. You can also read about what to do when Wegovy feels ineffective before making that call. If you have not yet started and want to know whether semaglutide is clinically right for you, check your eligibility through a free consultation with one of our GPhC-registered prescribers, a real clinician reviews your answers the same day.