Wegovy skin reactions: what to expect and when to seek help

Step 1: recognising the most common injection-site reactions

The most frequent skin-related complaint with Wegovy is a local reaction right where the pen touches the skin. You might notice a small red patch, some tenderness to press, mild itching or a slight raised area. These are normal immune responses to any subcutaneous injection and are not a sign that something has gone wrong. In clinical trials of semaglutide, local injection-site reactions affected a small but notable proportion of participants and were almost always described as mild to moderate. The NHS semaglutide medicines page lists injection-site reactions explicitly as a common side effect.

The practical fix is straightforward. Rotate the site with each weekly injection: alternate between the stomach, the front of the thigh and the outer upper arm, and avoid injecting into the exact same spot two weeks running. Let the pen reach room temperature for a few minutes before injecting, a cold pen straight from the fridge door can intensify the sting. Inject slowly and wait a couple of seconds before withdrawing. If you notice bruising, that usually reflects a small surface blood vessel being nicked rather than any medicine-related problem, and it resolves on its own.

Persistent redness at one site (lasting more than a few days, spreading, feeling hot, or developing into a firm lump) is worth flagging to your prescriber. Lipohypertrophy, a fat-tissue build-up from repeated injections in the same spot, is a known complication of subcutaneous medicines generally; it can affect how the medicine is absorbed, which is one reason site rotation matters beyond just skin comfort. If you want to understand what reactions at and around the injection site can look like, our page on reactions to Wegovy walks through the most commonly reported experiences in detail. You can find broader guidance on side effects across the treatment through our Wegovy side effects overview.

Step 2: spotting broader skin reactions that need a clinician's view

Beyond the injection site itself, some people report skin changes that appear elsewhere on the body. These are less common but carry more clinical weight. A generalised rash (itchy, blotchy or hive-like) that spreads across the torso, limbs or face after starting Wegovy should prompt a call to your GP or prescriber the same day. It could represent a hypersensitivity reaction, which sits on a spectrum from mild to serious.

Urticaria (hives) and angioedema (a deeper swelling that tends to affect the lips, eyelids, tongue or throat) are classified as uncommon side effects of semaglutide in its prescribing information. Angioedema involving the throat is a medical emergency; if swallowing becomes difficult or you feel your airway tightening, call 999 immediately. Our page on allergic reactions to semaglutide covers the full range of hypersensitivity signs in detail.

Hair thinning is another skin-adjacent concern that comes up regularly. It is not unique to Wegovy; telogen effluvium (a temporary shedding triggered by rapid weight change and calorie reduction) is well documented with most significant weight-loss interventions. It usually peaks around three to six months and self-resolves as weight stabilises. It is not a medicine allergy, though it does feel alarming. Mention it to your prescriber so they can review your nutritional intake alongside it; adequate protein during treatment is one of the factors that can reduce its severity.

Step 3: when to get medical help, and what cannot wait

Most injection-site marks need nothing more than patience and better rotation technique. But certain skin-related symptoms require same-day contact with a clinician, and a smaller set require 999 or A&E without delay. Here is a clear breakdown.

Contact your GP or prescriber the same day if you develop: a spreading rash or hives not confined to the injection site; facial swelling not involving the airway; significant itching across the body after a dose; or a hard, warm, enlarging lump at an injection site (which could indicate a localised infection).

Call 999 or go to A&E immediately if you experience: throat swelling, difficulty swallowing or breathing, a rapid heartbeat alongside a widespread rash, or collapse. These are signs of anaphylaxis, a rare but life-threatening reaction. Do not drive yourself.

Concerns that fall somewhere in the middle (for example, a mild rash you are unsure about) can be raised through our aftercare team, who are available seven days a week. You can also reach us via the contact page. For a broader picture of reactions that go beyond the injection site, the bad reactions to semaglutide page covers a wider range of scenarios.

Whatever the nature of your concern, every suspected adverse effect from a medicine can and should be reported through the MHRA's Yellow Card scheme. You do not need a diagnosis first, suspicion is enough. Reports from patients help build the post-market safety picture for medicines like Wegovy, which carries a Black Triangle (▼) designation indicating it is subject to additional monitoring.

Step 4: how skin reactions are managed within a clinically supervised treatment plan

Good management of skin reactions starts before the first injection, in the consultation. Our prescribers, overseen by our clinical team, ask specifically about skin conditions, allergies and previous reactions to injected medicines as part of a thorough assessment. People with a known history of severe allergic reactions or conditions like eczema that affect injection-site skin may need additional guidance before starting.

If you develop a reaction during treatment, the prescriber's first step is usually to establish whether it is local or systemic, mild or escalating. For mild local reactions, practical advice on technique and rotation is often enough. For generalised reactions, a temporary pause of the medicine may be considered while the cause is investigated, and our page on adverse reactions to Wegovy can help you understand what to expect from that process and when to escalate. Stopping Wegovy without clinical guidance is not recommended either, the decision should be made with your prescriber, who can weigh the reaction against your overall treatment progress.

The skin side effects of Wegovy cover more ground than most people expect before starting, and being prepared makes them far less unsettling when they do occur. A skin reaction is not automatically a reason to stop a medicine that may be providing significant health benefit, it is a reason to talk to someone who can help you decide. Our prescribers discuss suitability, side-effect management and ongoing monitoring as part of every consultation and repeat review. If you are considering starting Wegovy, or you have questions about a reaction you are already experiencing, start your free consultation and a clinician will review your situation the same working day.