Choosing the right Wegovy injection site

What the STEP 1 trial data tell us about subcutaneous delivery

Wegovy's effectiveness figures (roughly 15% average body-weight reduction over 68 weeks in the STEP 1 trial, published in the New England Journal of Medicine) were produced using subcutaneous injection into exactly these three sites under standardised rotation. The trial design matters here: it tells us that the results rely on correct, consistent technique, not just on the medicine itself. Absorption into subcutaneous fat is the intended route; an injection placed too shallow (into the skin layer) or too deep (into muscle) changes the pharmacokinetics and may cause avoidable discomfort.

Novo Nordisk's Summary of Product Characteristics, listed on the eMC, specifies that the injection should go into the subcutaneous tissue of the abdomen, thigh, or upper arm, and that sites should be rotated with each dose. Those are the boundaries the licensing data were built around. Everything else on this page unpacks what that means in practice.

If you are researching how the injection itself works (the pen mechanism, priming steps and needle attachment) that guidance covers the full administration sequence.

The abdomen, thigh and upper arm: what makes each site work

The abdomen is generally regarded as the most straightforward site, and many people starting treatment find it easiest to use. The area to target is roughly two to five centimetres away from the navel in any direction; avoiding the navel itself and the bony midline keeps the injection within good subcutaneous tissue. Absorption from the abdomen tends to be consistent, which is why clinical teams often suggest it for the first few injections while you are still getting used to the routine.

The front of the thigh (the outer, flatter surface rather than the inner) is a practical alternative, particularly if the abdomen is not accessible or comfortable. It is a site many people use when injecting alone at home, because it is easy to see and reach without assistance. The upper part of the thigh rather than the knee area gives the most reliable tissue depth.

The outer upper arm is the third option. Most people find this site easier with help from another person, though it is possible to reach it alone. It is worth knowing that the arm as a Wegovy injection site is fully licensed and produces equivalent absorption, it is not a fallback reserved for unusual circumstances. For a closer look at site-specific technique, including how the upper arm compares in practice, our guide to all Wegovy injection sites goes into more detail.

Rotation: the practical rule that protects your skin

Rotating the site each week is one of those instructions that sounds like fine print but has a real purpose. Injecting repeatedly into the same small area causes lipohypertrophy, a localised thickening of the fatty tissue that looks and feels like a soft lump under the skin. Once that tissue is affected, absorption from it becomes unpredictable, and some people notice their medicine seems less effective without realising the injection site is the variable that has changed.

The NHS semaglutide medicines guidance confirms that sites should be rotated and that you should avoid skin that is tender, bruised, red, hard, or affected by scarring. A sensible system is to move between the three areas in a fixed order (abdomen one week, thigh the next, upper arm the week after) and within each area, to vary the exact point slightly each time. Some people mark a small calendar note alongside their injection-day reminder; it takes seconds and keeps the rotation consistent without having to remember.

A fresh needle for every injection matters here too. A used needle tip becomes microscopically blunted, which increases the chance of skin trauma at the injection site. Replacement pen needles are available separately if you need to top up.

Skin preparation and what to do if you have concerns

Before injecting, let the pen reach room temperature if it has been stored in the fridge, this typically takes around 30 minutes and can make the injection more comfortable. Cleaning the skin with an alcohol swab and allowing it to dry fully before injecting is the standard preparation step.

If you notice persistent redness, swelling, or a lump at any injection site that does not settle within a few days, let your prescriber know. These reactions are usually minor and technique-related, but your clinical team can advise on adjustments. For the best site to inject Wegovy when you have a specific concern (skin sensitivity, limited dexterity, or a preference for the arm) speaking to a prescriber gives you a tailored answer rather than a general one.

Side effects from Wegovy are mostly gastrointestinal (nausea, digestive changes) rather than injection-site specific, but any suspected side effect can be reported via the MHRA's Yellow Card scheme. If you are thinking about starting treatment and want to understand how Wegovy fits alongside other options, our weight-loss treatment overview covers the landscape clearly, and our page on weight loss injections including Ozempic explains how semaglutide-based treatments compare. If you plan to use the upper arm and want detailed technique guidance, our page covering the semaglutide arm injection site walks through exactly what to do.