Wegovy injection sites: what the evidence says about the upper arm

What the SmPC and NHS guidance actually say about upper-arm injections

The Wegovy Summary of Product Characteristics, published on the Electronic Medicines Compendium, lists the outer upper arm as a fully approved injection site alongside the abdomen and thigh. There is no hierarchy among the three. The NHS's own medicines information for semaglutide reflects the same three-site approach, and NHS guidance on semaglutide advises rotating the site each week to keep skin tissue healthy over the long course of treatment.

One misconception worth clearing up gently: some people assume the stomach is the "main" site and the arm is a fallback. It isn't. All three sites deliver the medicine into subcutaneous tissue, and clinical data from the STEP 1 trial (which reported an average 15% reduction in body weight over 68 weeks) did not restrict injection site, meaning participants across all three sites contributed to those results.

For anyone exploring all the licensed Wegovy injection sites together, the rotation principle is consistent: each new dose goes to a different site or a clearly different spot within the same site, never the same area twice in a row.

Exactly where on the arm to inject Wegovy

The correct location is the outer, mid-portion of the upper arm, and our dedicated guide to the Wegovy arm injection site covers exactly where to position the pen, what to avoid, and how to get a consistent result each time. Pulling at the outer arm when you're giving yourself an injection is genuinely difficult. That practical problem is why many solo users gravitate to the thigh or abdomen instead, and it is a perfectly legitimate reason to choose a different site on weeks when no one is around to help.

When a partner or carer administers the injection, technique is straightforward. Expose the arm, gently pinch a fold of skin, insert the Wegovy pen needle at the angle described in your Patient Information Leaflet, and hold it in place for the count stated in the instructions before withdrawing. Using alcohol swabs to clean the skin beforehand is standard practice; allow the area to dry before injecting. Injecting into wet skin stings more and can affect comfort.

The full detail on technique (hold time, needle depth, what to do if you see blood) is in your PIL. Your prescriber and the nume FAQs can also point you to the right reference if anything is unclear.

Site reactions and when they need attention

Redness, mild itching or a small lump at an upper-arm injection site are common and usually resolve within a few days. They are typically the result of injecting into the same spot repeatedly, which is why rotation is not optional advice. NHS semaglutide information notes injection-site reactions among the known side effects and describes them as generally mild.

A reaction that spreads beyond the injection area, causes significant swelling, feels warm to the touch, or does not settle within a few days should be reported to your prescriber. Likewise, a hard lump that persists over several injection cycles (a sign of lipohypertrophy) means that spot should be rested completely until it resolves. If you are on treatment through Wegovy via a regulated service, contact your clinical team rather than waiting for the next scheduled review. Aftercare support exists precisely for this kind of question.

On the broader side-effect picture, GI symptoms (nausea, loose stools, reflux) are far more commonly reported than injection-site issues and tend to be most noticeable after a dose increase. They generally ease within days to a couple of weeks as your system adjusts. Any symptom that is severe or persistent (stomach pain that spreads to the back in particular) warrants urgent medical attention; this is one of the key signals flagged by the MHRA in its safety communications on GLP-1 medicines.

Practical decisions: arm, thigh or abdomen?

There is no clinically superior site. The choice comes down to access, comfort and consistency of rotation. Abdomen works well for most people injecting alone. The thigh is easy to see and grip. The arm is ideal when a partner is helping or when you want to spread the weekly injection across all three anatomical zones systematically.

Some people on longer courses find the abdomen becomes their default and skin texture slowly changes; deliberately scheduling the arm and thigh into the rotation prevents that. If you want a full breakdown of all the sites to inject Wegovy, including how to rotate between them and what to watch for at each location, that guide covers the practical detail in one place. If you are also considering how semaglutide injection sites compare across different branded medicines, the anatomical guidance is consistent, the active molecule is the same whether prescribed as Wegovy or another semaglutide product.

For anyone weighing up the broader landscape of weight-loss treatment options, including how injectable and oral GLP-1 treatments differ in practice, a prescriber is the right first call. The cost picture for private treatment is worth understanding too, the Wegovy cost and access page sets out what a private prescription typically involves without hiding the numbers.

At nume, every patient on Wegovy has 7-day aftercare access for exactly these practical questions: which site to use this week, how to manage a local reaction, whether a symptom warrants a GP call. Speak to our prescribers to start a consultation, or if you are already on treatment and have a question that won't wait.