Rash from Wegovy: Causes, Management and When to Seek Help

Wegovy (semaglutide 2.4 mg) is a GLP-1 receptor agonist licensed for weight management in adults with obesity or overweight with comorbidities. Whilst gastrointestinal side effects are most common, skin reactions including injection site reactions and rashes can occur. Understanding the types of rash associated with Wegovy, when to seek medical attention, and how to manage these reactions is essential for safe treatment. This article provides comprehensive guidance on identifying, managing, and preventing rash from Wegovy, aligned with UK clinical practice and MHRA guidance.

Understanding Wegovy and Skin Reactions

Wegovy (semaglutide 2.4 mg) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed by the MHRA for weight management in adults with obesity or overweight with weight-related comorbidities. It works by mimicking the action of the naturally occurring hormone GLP-1, which regulates appetite, slows gastric emptying, and enhances insulin secretion. Administered as a once-weekly subcutaneous injection, Wegovy has demonstrated significant efficacy in clinical trials for sustained weight loss when combined with lifestyle modifications.

Whilst gastrointestinal adverse effects such as nausea, vomiting, and diarrhoea are the most commonly reported side effects, skin reactions can occur in some patients. According to the Wegovy Summary of Product Characteristics (SmPC), injection site reactions are reported as 'common' (affecting between 1 in 10 and 1 in 100 people), while hypersensitivity reactions including urticaria are classified as 'uncommon' (affecting between 1 in 100 and 1 in 1,000 people).

Injection site reactions are relatively common with subcutaneous biologics and typically manifest as erythema, swelling, pruritus, or mild discomfort at the injection site. These reactions are usually self-limiting and resolve within a few days. However, more widespread or persistent rashes warrant clinical evaluation to exclude allergic reactions or other dermatological conditions. Serious hypersensitivity reactions, including anaphylaxis and angioedema, have been reported with semaglutide and require immediate discontinuation and emergency medical care.

Types of Rash Associated with Wegovy

Skin reactions associated with Wegovy can be broadly categorised into localised injection site reactions and generalised cutaneous manifestations. Understanding these distinctions helps patients and clinicians identify the nature and potential severity of the reaction.

Localised injection site reactions are the most frequently reported dermatological adverse effects. These typically include:

• Erythema (redness) at the injection site

• Pruritus (itching) localised to the area

• Swelling or induration (hardening of tissue)

• Mild pain or tenderness

• Bruising (ecchymosis) in some cases

These reactions usually appear within hours to days following injection and typically resolve spontaneously within 2–5 days without specific intervention. They are generally considered mild and do not necessitate treatment discontinuation.

Generalised rashes are less common but may indicate a systemic hypersensitivity reaction. These can present as:

• Urticaria (hives) — raised, itchy wheals that may appear anywhere on the body

• Maculopapular rash — flat or slightly raised red spots, sometimes with small bumps

• Generalised pruritus without visible rash

In rare instances, patients may develop angioedema (swelling of deeper skin layers, particularly around the face, lips, or throat) or anaphylaxis, which requires immediate medical attention and discontinuation of treatment. Any extensive blistering or mucosal involvement should prompt urgent assessment.

It's important to note that painful, warm, or enlarging lesions at injection sites may indicate infection or cellulitis rather than a simple reaction, requiring different management.

When to Seek Medical Attention for a Wegovy Rash

Most injection site reactions are mild and self-limiting, requiring only observation and basic symptomatic management. However, certain features warrant prompt medical evaluation to exclude serious allergic reactions or complications.

Seek urgent medical attention (call 999 or attend A&E) if you experience:

• Difficulty breathing or swallowing

• Swelling of the face, lips, tongue, or throat (angioedema)

• Widespread urticaria accompanied by dizziness, rapid pulse, or feeling faint

• Severe chest tightness or wheezing

• Blistering, peeling skin, or mucosal involvement (mouth, eyes, genitals)

These symptoms may indicate anaphylaxis or a severe hypersensitivity reaction requiring immediate emergency treatment with adrenaline and supportive care. If you suspect a hypersensitivity reaction, stop using Wegovy immediately and do not take further doses.

Contact your GP or prescribing clinician within 24–48 hours if:

• The rash spreads beyond the injection site or worsens progressively

• Injection site reactions persist beyond one week or become increasingly painful

• You develop fever, malaise, or other systemic symptoms alongside the rash

• The rash is accompanied by joint pain or swelling

• You experience recurrent or worsening reactions with each injection

• The injection site becomes increasingly warm, painful, or shows signs of infection

For urgent but non-emergency concerns, you can also contact NHS 111 for advice.

Routine monitoring is appropriate for mild, localised injection site reactions that improve within a few days. However, maintaining a symptom diary can help identify patterns or escalating severity. If you are uncertain about the significance of your symptoms, it is always advisable to seek professional guidance. The MHRA Yellow Card scheme (www.yellowcard.mhra.gov.uk) allows patients and healthcare professionals to report suspected adverse drug reactions, contributing to ongoing pharmacovigilance and medication safety.

Managing and Treating Rash from Wegovy

Management of rash associated with Wegovy depends on the type, severity, and extent of the skin reaction. Most localised injection site reactions can be managed conservatively with simple measures, whilst more extensive or severe reactions may require pharmacological intervention or treatment modification.

For mild localised injection site reactions:

• Cold compress application — apply a clean, cool (not ice-cold) compress to the affected area for 10–15 minutes to reduce inflammation and discomfort

• Avoid rubbing or scratching the injection site, as this may exacerbate irritation

• Topical emollients — regular application of fragrance-free moisturisers can soothe dry or irritated skin

• Oral antihistamines — non-sedating antihistamines such as cetirizine or loratadine may help relieve itching if troublesome

For more significant or generalised rashes:

• Topical corticosteroids — mild-to-moderate potency topical steroids may be prescribed for inflammatory rashes. Use as directed by your healthcare professional; avoid potent steroids on the face, flexures, or genital areas, and limit duration of use

• Oral antihistamines — may be used regularly rather than as needed for urticarial reactions

• Avoidance of triggers — identify and avoid potential exacerbating factors such as hot showers, tight clothing over injection sites, or known allergens

When treatment modification is necessary:

If reactions are recurrent or troublesome despite symptomatic management, your prescriber may consider:

• Delaying dose escalation by 4 weeks until symptoms improve

• Maintenance at a lower dose (1.7 mg) if 2.4 mg is not tolerated

• Switching injection sites systematically (abdomen, thigh, upper arm) to minimise localised reactions

Important safety note: If you experience signs of hypersensitivity or a serious allergic reaction, stop Wegovy immediately and seek urgent medical care. Do not restart the medication without medical advice. For non-serious reactions, consult your prescriber before making any changes to your treatment regimen.

If your injection site becomes increasingly painful, warm, or shows signs of infection (redness spreading, pus, fever), seek prompt medical review as antibiotics may be required.

Prevention and Risk Reduction Strategies

Whilst not all skin reactions can be prevented, several evidence-based strategies can minimise the risk and severity of injection site reactions and dermatological adverse effects associated with Wegovy.

Optimal injection technique:

• Rotate injection sites systematically — avoid injecting into the same area repeatedly. Use different sites within the recommended areas (abdomen, thigh, upper arm) and maintain at least 2–3 cm distance from previous injection sites

• Ensure proper needle insertion — inject at a 90-degree angle into subcutaneous tissue, not intramuscularly or intradermally

• Allow the medication to reach room temperature — remove the pen from the refrigerator approximately 30 minutes before injection, but follow the storage instructions in the Patient Information Leaflet (PIL) and do not exceed recommended storage temperatures

• Clean the injection site with an alcohol wipe and allow it to dry completely before injecting

• Do not inject into areas with active skin conditions — avoid sites with rashes, bruises, scars, or inflammation

Skin preparation and aftercare:

• Maintain good skin hydration — regular use of emollients can improve skin barrier function and potentially reduce irritation

• Avoid tight clothing over fresh injection sites for several hours

• Do not massage the injection site immediately after administration, as this may increase local irritation

Patient education and monitoring:

• Keep a symptom diary noting injection sites, any reactions, and their duration

• Report persistent or worsening reactions to your healthcare provider promptly

• Ensure you have received proper training in injection technique from a healthcare professional

• Be aware of the signs of serious allergic reactions and have an action plan

If you have previously experienced a serious hypersensitivity reaction to semaglutide, you should not be re-exposed to the medication. If you have a history of allergic reactions to medications, discuss this with your prescriber before starting Wegovy, as they may recommend additional monitoring or precautions.

Always refer to the Wegovy Patient Information Leaflet for device-specific instructions on administration, storage, and permitted injection sites.

Scientific References

1. Wegovy | European Medicines Agency (EMA).
2. Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen - Summary of Product Characteristics (SmPC).
3. Semaglutide for managing overweight and obesity | Guidance | NICE.
4. GLP-1 receptor agonists: reminder of the potential side effects and to be aware of the potential for misuse.

Frequently Asked Questions