Where should semaglutide be injected — and does site choice matter?

Which three sites are approved, and where exactly on each one?

The abdomen, front-to-outer thigh, and outer upper arm are the sites stated in the Wegovy licensed prescribing information. Within each area there are boundaries worth knowing. On the abdomen, stay at least 5 cm clear of the navel in any direction; the flanks and lower belly are fine, but the area directly above the belly button is not. On the thigh, aim for the outer-to-front portion of the upper half, roughly the area that faces forward when you stand. The outer upper arm (the deltoid region, not the inner arm) is the third option, though it is the trickiest to reach on your own; many people reserve it for days when a partner or carer can assist.

A quick habit worth building: before each injection, run two fingers across the site you plan to use. If you feel a firm lump, a bruise, or notice redness from a previous injection, move to a different spot or a different site entirely. That 10-second check takes less effort than managing a localised reaction. The NHS medicines page for semaglutide confirms these three sites and recommends checking the skin before each use.

The outer thigh and abdomen tend to be the easiest for self-injection, and if you want a full walkthrough of technique and placement, the guide on where to inject semaglutide covers each approved area in practical detail. The abdomen, in particular, is where most people start, there is usually enough subcutaneous tissue to work with, and you can see exactly what you are doing.

Why does rotating injection sites actually matter?

Injecting repeatedly into exactly the same spot causes a condition called lipohypertrophy, a thickening and scarring of fatty tissue that develops gradually and without much pain, which is part of why people miss it. Once a patch of skin becomes fibrous, the medicine absorbs inconsistently from that area. You may be injecting the full dose yet getting less predictable results, not because the medicine has changed but because the tissue has.

Rotation solves this. A practical way to manage it: divide each site into a rough grid and move systematically around it, never returning to the same small patch within a few weeks. Some people keep a simple note on their phone, left thigh this week, right thigh next, abdomen the week after. It does not need to be elaborate; it just needs to be deliberate. If you are wondering about timing and routine as well as site, the page on when to inject semaglutide covers the day-of-week rules in more detail.

Injection-site reactions (temporary redness, mild itching, a small bump) are listed as common side effects. They generally fade within a day or two. A lump that persists for more than two weeks, or skin that becomes markedly discoloured or hard, is worth raising with your prescriber.

Does the injection site affect how much semaglutide you absorb?

Studies on subcutaneous GLP-1 medicines show that absorption varies somewhat by site, with the abdomen typically producing the most consistent uptake. That said, the prescribing information for Wegovy states that site rotation among the three approved areas is acceptable, the clinical trials were conducted with all three sites used, so the licensed efficacy data already accounts for that variation. The practical message: stick to the three approved areas, rotate consistently, and do not inject into muscle or into fatty tissue that has already become scarred from repeated use.

Temperature is a related variable. Injecting a pen that has just come from the fridge can increase local discomfort. Letting the pen sit at room temperature for 15 to 30 minutes before use (without warming it artificially) can make the injection more comfortable, and there is a specific page on whether Wegovy should be injected cold if that is something you are thinking through. Storage and handling rules are also covered in detail in the Wegovy Patient Information Leaflet, which is the definitive reference for your specific pen.

If you are still deciding whether Wegovy is the right option for your situation, or if you are already on treatment and want clinical support with technique questions, the Wegovy overview sets out the full picture, and our prescribers are available for aftercare seven days a week. For a broader look at what is available, weight-loss treatments lays out the options side by side. Separately, if cost is on your mind, the Wegovy cost page covers what private treatment typically involves.

What should you do if you notice a problem at the injection site?

Mild, transient reactions are expected and not a reason to stop. A small red mark, brief itching, or minor swelling at the point of injection usually resolves within 48 hours. Rotating sites properly is the main prevention strategy, and if you are unsure whether your pen is functioning correctly between uses, the page on the brown Wegovy pen explains what that discolouration means and when to be concerned.

Seek prompt medical advice if you notice: a reaction that spreads or worsens rather than settling; significant swelling, warmth or pain suggesting possible infection; a firm nodule that does not disappear after several weeks; or signs of a wider allergic response (rash away from the injection site, difficulty breathing, swelling of the face or throat). The last scenario is rare but constitutes a medical emergency, call 999 or go to A&E.

You can report any suspected side effect (whether at the injection site or elsewhere) through the MHRA's Yellow Card reporting scheme. That scheme also allows you to flag suspect medicines or packaging if you have any concerns about the product you received. Keeping your used pens in an approved sharps container is the correct disposal method and is required by law.