Can Wegovy injections cause skin changes at the injection site?

Yes — mild redness, itching, or small lumps can occur and usually settle. Rotate sites weekly to prevent lipohypertrophy (fatty thickening) and avoid injecting into scars, moles, or irritated skin. If you see persistent nodules, colour changes, warmth, or pain, switch location and ask your clinician to review technique and needle size.

Why skin reactions happen

Wegovy (semaglutide) is injected into the fatty layer under the skin (the subcutaneous tissue), where small local reactions can occur. NICE TA875, MHRA product information, and NHS training materials all describe redness, mild swelling, or itching as common, short-lived effects. These responses reflect the body’s normal reaction to the needle and fluid rather than an allergy to the medicine. Most settle within a few hours or days without treatment. Occasionally, a small raised area or firmness under the skin develops after repeated injections in the same spot — known as lipohypertrophy. Rotating sites each week prevents this by giving the tissue time to recover.

Typical minor reactions

According to MHRA data and NHS experience, the most frequent skin changes are:

• Redness or slight warmth immediately after injection.

• Mild itching or tenderness that fades within 24–48 hours.

• Tiny bumps or firm spots at the site, which soften naturally.

These effects are harmless and don’t affect how Wegovy works. NICE and NHS clinicians advise keeping the area clean, avoiding tight clothing over the site, and not rubbing or scratching after injection. Some people find a cool compress for a few seconds after injecting helps calm the skin.

Lipohypertrophy and lipoatrophy

Injecting repeatedly into the same area can lead to two opposite issues: lipohypertrophy (thickened fatty tissue) or, rarely, lipoatrophy (fat loss creating small dips). Both result from repeated local tissue stimulation rather than the medicine itself. NICE TA875 and MHRA summaries recommend rotating between abdomen, thigh, and upper arm, spacing injections at least 2–3 cm from the previous spot. NHS training nurses often teach patients to move in a circular pattern across the abdomen or alternate thighs weekly. Using a new needle every time also helps by reducing microtrauma and infection risk.

Recognising when to seek review

Most site reactions resolve quickly, but certain changes require professional review:

• Persistent redness or swelling lasting more than three days.

• Pain, warmth, or visible streaking away from the site (possible infection).

• Hard nodules that don’t shrink over several weeks.

• Noticeable skin colour changes or pitting.

If these occur, switch injection location and contact your clinic or pharmacist. Clinicians may check your needle length or technique and occasionally prescribe a mild topical treatment if inflammation persists. NICE and MHRA guidance advise against injecting into damaged or inflamed skin until it heals.

Preventing irritation and infection

Good preparation and hygiene greatly reduce problems. NHS injection guides recommend:

• Wash hands and clean the site before injection.

• Use a new sterile needle each time.

• Let any alcohol wipe dry fully before injecting to avoid stinging.

• Hold the pen flat and still until the indicator completes.

• Apply gentle pressure afterward instead of rubbing.

Store pens correctly — cold before first use, below 30 °C afterward — to keep the solution clear and stable. If a pen appears cloudy or discoloured, don’t use it; return it to the pharmacy for advice.

When allergic reactions are suspected

True allergic responses to semaglutide are rare. MHRA safety reports note that most “rash” complaints are local irritation, not systemic allergy. However, widespread hives, facial or tongue swelling, or breathing difficulty require urgent medical attention. If only the injection site is affected but the area becomes increasingly sore or hot, clinicians may check for infection or sterile inflammation. It’s safe to pause injections temporarily while symptoms are evaluated.

Needle size and technique

Occasionally, discomfort stems from using an unsuitable needle length or poor technique. NHS nurses confirm that standard Wegovy pen needles (usually 4–6 mm) work for most adults, but those with very little subcutaneous fat may benefit from gently pinching up the skin to avoid intramuscular injection. Conversely, those with thicker abdominal tissue may need to ensure the pen is pressed flat for consistent delivery. Technique refreshers are offered in many NHS weight-management clinics to review alignment, pressure, and site rotation.

Practical comfort tips

A few practical habits can improve comfort and skin condition:

• Keep injections on the same weekday to establish routine.

• Warm the pen gently in your hands before use if it feels cold.

• Choose the abdomen for the smoothest absorption and least irritation.

• Avoid areas bruised from previous injections.

• Apply a clean, cool flannel for a few seconds afterward if irritation occurs.

Some users find rotating between left and right sides of the abdomen easiest to track. Others mark previous spots lightly on a body diagram or note them in their injection log. NHS clinicians encourage using whichever system makes consistency easiest.

Evidence from research and practice

Clinical data from STEP trials and post-marketing surveillance reviewed by Nature Medicine (2024) and Lancet Diabetes & Endocrinology (2024) confirm that local skin reactions are among the most common but least serious side effects of semaglutide. They occur in a small percentage of users and rarely lead to discontinuation. NICE TA875 and MHRA reports classify them as mild-to-moderate events that typically improve as users gain experience with self-injection and site rotation.

The essential point

Mild redness, itching, or small bumps at Wegovy injection sites are common and temporary. Rotating sites, using new needles, and keeping skin clean prevent irritation and fatty thickening. Persistent or painful reactions should be reviewed by your clinician to check technique or needle fit. NICE, NHS, MHRA, and SMC guidance all agree: correct injection habits make skin reactions rare, brief, and easily managed while keeping treatment safe and effective.