Are there any known injection site reactions to Wegovy?

Yes, common local reactions include redness, mild swelling, or itching at the injection site. These are usually short-lived and improve with rotation of injection areas. Applying a cool pack after injecting may help settle irritation. Serious reactions are very rare, but patients are advised to seek medical help if swelling spreads or becomes painful.

Common local reactions

Like many injectable medicines, Wegovy (semaglutide) can cause minor site reactions. The most frequently reported are redness, itching, mild swelling, or tenderness where the needle enters the skin. These effects usually appear within the first 24 hours and settle within a few days. NHS patient guidance notes that such reactions are more likely during the first months of treatment while patients are still adjusting. In clinical practice, nurses often reassure patients that these effects are not unusual and can often be prevented by good technique.

Evidence from clinical trials

The STEP trials, which formed the basis of NICE TA875 approval, tracked side effects closely. In STEP-1 and STEP-5, injection site reactions were reported in a small percentage of participants, but they were mostly mild and rarely led to treatment withdrawal. SELECT, the cardiovascular outcomes study, also confirmed a similar safety profile: gastrointestinal issues were the main side effects, with injection site reactions uncommon and non-serious. This evidence reassures patients that local skin reactions are usually temporary and manageable.

The role of site rotation

NICE and NHS guidance strongly recommend rotating injection sites each week. This prevents irritation and reduces the risk of lipohypertrophy — a thickening or lumpiness of the fatty layer caused by repeated injections in the same spot. Rotation can be within the same general area (abdomen, thigh, or upper arm), but injections should be at least a finger-width or two from the previous one. NHS weight management teams often provide site maps or checklists to help patients keep track. This advice, borrowed from decades of experience in insulin care, is key to protecting skin health.

Self-care measures for irritation

Minor irritation can usually be managed with simple steps. Applying a cool pack for a few minutes after the injection may ease swelling or itching. Gentle cleansing of the site with mild soap and water before injection also lowers the risk of reactions. NHS nurses advise patients not to rub or scratch the site, as this can worsen irritation. Wearing loose clothing around the injection area for a few hours afterwards may also help. These strategies are based on both clinical experience and patient feedback from weight management services.

When to seek medical advice

While most reactions are mild, patients are advised to contact their clinician if symptoms worsen or fail to improve after several days. Spreading redness, increasing pain, or swelling accompanied by fever may suggest infection and require prompt review. The MHRA Yellow Card scheme encourages patients and professionals to report unusual or severe reactions, helping regulators monitor safety at a national level. Although very rare, serious allergic reactions — such as widespread rash, difficulty breathing, or severe swelling — require urgent medical attention via NHS 111 or emergency services.

Lessons from NHS practice

In NHS weight management clinics, staff monitor injection technique closely during early visits. Many minor reactions are linked to issues such as using the same site too often, injecting too shallow or too deep, or not holding the pen in place for the recommended time. Once these points are corrected, most patients report fewer problems. Pharmacists also play a role by advising on needle use and providing sharps bins for safe disposal, which reduces the risk of contamination or accidental skin injury.

Reassurance from long-term data

Longer-term data from the STEP-5 trial, which followed patients for two years, showed that injection site reactions did not increase with time. In fact, most participants experienced fewer issues once injection technique became routine. NICE TA875 draws on this evidence, emphasising that education and support reduce the likelihood of ongoing irritation. NHS guidance reassures patients that while injection site reactions are possible, they are rarely serious and should not discourage continued treatment when managed properly.

The main message

Mild injection site reactions such as redness, swelling, or itching are common with Wegovy, especially early in treatment, but they usually settle quickly and are easy to manage with simple measures like site rotation and cool packs. Evidence from NICE, NHS guidance, MHRA monitoring, and the STEP and SELECT trials confirms that serious reactions are very rare. The main message is clear: safe technique, regular site rotation, and prompt reporting of anything unusual keep treatment on track and protect both comfort and confidence in long-term Wegovy use.