Using the back of the arm as a Wegovy injection site

Step 1, choose the right spot on your arm

The target area is the back of the upper arm, roughly midway between the shoulder and the elbow, in the soft tissue over the triceps. Avoid the bony tip of the shoulder, the elbow crease, and any areas that feel firm or knotted. The skin there needs to pinch into a fold roughly 2–3 cm wide; if it does not, the area may be too lean for a comfortable subcutaneous injection and the abdomen or thigh would be a better choice that day.

Rotate within the upper arm itself (slightly left, slightly right, slightly higher or lower from the previous shot) so you are never placing one injection directly on top of a recent one. Scar tissue and skin thickening from repeated same-spot dosing can slow absorption and cause unnecessary discomfort. Your Patient Information Leaflet maps this out; if anything is unclear, the clinical team is there to help.

It is worth acknowledging that if you are new to self-injecting, the back of the arm can feel intimidating. That is entirely normal. Most people find the abdomen the easiest starting point while they build confidence, then try the arm when a friend or partner is around to assist.

Step 2, prepare cleanly and position carefully

Wash your hands thoroughly. Let the pen reach roughly room temperature if you have taken it straight from the fridge, injecting cold semaglutide is not dangerous but can sting more than necessary. Check the pen window shows the correct fill and colour before you begin.

For a solo attempt, sitting in front of a mirror at an angle is the most practical approach: it lets you see the site and line up the pen without twisting sharply. A wall-mirror works, as does propping a phone to use the camera. Remove the cap, pinch the skin gently if needed, and place the pen flat against the skin at a 90-degree angle. Press firmly and hold for the full count the leaflet specifies (typically around 10 seconds) to ensure the full dose is delivered before you withdraw.

If someone else is administering the injection, the process is considerably simpler: you sit or stand comfortably with the arm relaxed at your side, and they position the pen on the pinched skin just as they would for a thigh injection. The broader guidance on arm injection technique for Wegovy covers the anatomical landmarks in more detail.

Step 3 (aftercare and what to watch for

Once the pen is withdrawn, press lightly with a clean finger or gauze) do not rub, as rubbing can irritate the site. A small red mark or mild bruising is common and settles within a day or two. If the site becomes swollen, warm and tender beyond 48 hours, or if you notice any lump that persists for more than a week, mention it to your prescriber at the next contact point.

Injection-site reactions are among the more frequently reported side effects with semaglutide, per the NHS medicines information for semaglutide. They are usually mild and resolve on their own. Rotating consistently is the most effective preventive measure. If you are injecting into the arm regularly and notice persistent lumps or thickened skin, move to the abdomen or thigh for a few weeks to let the tissue recover.

Dispose of the used pen in a sharps container immediately after use, never in household waste. Keep spare pens refrigerated at 2–8°C and consult the leaflet for the exact period a pen may be kept at room temperature once removed from the fridge.

How site choice fits into the bigger clinical picture

The injection site you use does not change the dose, but absorption rates can differ slightly between sites, studies with other subcutaneous medicines suggest the abdomen tends to give the most consistent uptake. This is not unique to Wegovy and is rarely clinically significant at weekly dosing intervals, but it is a reason not to arbitrarily switch sites immediately before a clinical review if you want a consistent baseline.

For a broader look at how Wegovy works and what the trial data show, the Wegovy treatment overview sets out the evidence clearly. If you are wondering about weight returning after stopping Wegovy, that is a separate question with its own clinical reasoning worth reading before any changes. And if back discomfort has been on your mind since starting treatment, it is worth reading about whether Wegovy can cause back pain before drawing conclusions, including the more specific question of how back pain and Wegovy interact for people already mid-treatment.

Wegovy is a prescription-only medicine; a prescriber reviews the full picture (your medical history, current dose, any side effects) before every supply. If you are considering starting treatment or have questions about your current site technique, speaking to our prescribers is the natural next step. There is no obligation and no charge for the consultation itself.

For context on the cost of private treatment, the Wegovy cost and access guide explains what a legitimate prescription price covers and what to be cautious of.