Wegovy is subcutaneous, not intramuscular — here's what that means in practice

Step 1, understand the two injection layers and why Wegovy uses the shallower one

Subcutaneous tissue sits between the skin and the muscle. It is made up largely of fat, which is well supplied with small blood vessels. Medicines injected here are absorbed slowly and consistently into the bloodstream, avoiding the faster, more variable absorption that comes with an intramuscular injection.

For semaglutide, that slow uptake is an advantage. Wegovy is designed to act over a full week, and a steady release from subcutaneous tissue supports that long-acting profile. If you are curious about why the pharmacokinetics work this way, the detail on semaglutide's subcutaneous absorption goes into the mechanism thoroughly.

Intramuscular injections, by contrast, deliver medicine directly into muscle tissue, where blood flow is higher and absorption is quicker. Vaccines and some antibiotics use that route on purpose. Wegovy does not, and the pen is not designed for it. The needle is not long enough to reach muscle reliably at the licensed sites, and attempting an intramuscular injection would change the drug's absorption in unpredictable ways. The subcutaneous semaglutide page covers the pharmacological rationale if you want the fuller picture.

Step 2, choose the right site and prepare it correctly

The licensed sites for Wegovy are the abdomen (avoiding the two inches directly around the navel), the front of the thigh, and the outer upper arm. Each works because it has enough subcutaneous fat to accept the injection comfortably and absorb the medicine consistently.

Rotating sites each week matters. Injecting the same spot repeatedly can cause lipohypertrophy (a build-up of fatty tissue at the injection point) which alters absorption and can make the area lumpy and tender. A simple habit that takes under a minute: before each injection, run a finger lightly over the last site you used. If it feels firmer or bumpier than surrounding skin, choose a different location this week.

The skin should be clean and dry. Pinching the skin slightly before inserting the needle helps ensure the needle stays in subcutaneous tissue rather than slipping into muscle at lean sites such as the thigh. The Wegovy injection technique guide walks through the full process. The Patient Information Leaflet included with every pen is the definitive reference for angle, pinching and needle insertion, always read it.

Step 3, know what subcutaneous delivery means for common side effects

Most of Wegovy's side effects relate to semaglutide's action on the gut rather than to the injection route itself. Nausea, loose stools, indigestion and reduced appetite are GI effects that arise because GLP-1 receptors slow gastric emptying and influence appetite signalling centrally. These are common when starting treatment or moving to a higher dose, and they typically ease within the first couple of weeks as your body adjusts. The Wegovy overview page covers the full side-effect profile in plain terms.

Injection-site reactions (mild redness, itching or bruising) are local responses to subcutaneous delivery and are generally short-lived. They are less common with Wegovy than with older subcutaneous medicines largely because the pen's needle is fine and short. Persistent site reactions, or anything resembling an allergic response, should be reported to your prescriber. You can also report suspected side effects directly through the MHRA's Yellow Card scheme.

People who are particularly lean sometimes worry they lack enough subcutaneous tissue. This is worth raising with your prescriber; the abdomen usually provides adequate depth even when body fat is low, and your clinical team can advise on technique adjustments if needed.

Step 4, subcutaneous route, cardiovascular research and broader licensed uses

The subcutaneous semaglutide in Wegovy is the same formulation studied in the SELECT trial, which led to a UK licence extension covering cardiovascular risk reduction in eligible adults. Semaglutide's cardiovascular evidence is explained separately, but it is worth noting that the delivery route remained subcutaneous throughout that research. Nothing about the injection method changes when the indication does.

Oral semaglutide exists as a separate formulation with an absorption enhancer and a very different dosing schedule, it is not interchangeable with the subcutaneous pen. The NHS patient-level guidance on semaglutide on the NHS website covers both forms clearly and is worth bookmarking alongside your Patient Information Leaflet.

If you have been using Wegovy and want to explore how it compares with other treatment options, or if you are considering starting, a free consultation with our prescribers is the right first step. A GPhC-registered Independent Prescriber reviews every consultation the same day and will discuss injection technique, suitability and the clinical programme alongside your application.