Dermatologic Effects of Wegovy (Semaglutide)
Wegovy does not preferentially affect specific anatomical areas of the skin, but when dermatologic reactions occur, they have been documented most commonly on the trunk, legs, and areas surrounding injection sites.
Documented Skin Reaction Patterns
The available evidence shows that dermatologic adverse effects from semaglutide are uncommon but can manifest in distinct patterns when they occur:
Hypersensitivity Reactions
- Trunk and extremity involvement is most frequently reported, with documented cases showing eruptions on the legs, back, chest, bilateral flanks, and lower abdomen 1
- These reactions typically present as subepidermal blisters with eosinophils on histology, consistent with drug hypersensitivity 1
- Symptom onset can occur anywhere from 3 weeks to 10 months after initiating therapy 1
- Resolution typically occurs within 1 month of discontinuing semaglutide 1
Allodynia (Skin Tenderness)
- A more recently recognized adverse effect is generalized allodynia or skin pain to touch, which appears to be dose-dependent and associated with the 2.4 mg weekly dose used in Wegovy 2
- This reaction does not show specific anatomical predilection but rather presents as diffuse skin tenderness 2
- In documented cases, symptoms either resolved after discontinuation or, in patients who continued therapy, improved after approximately 4 months 2
Clinical Implications
Common Gastrointestinal Side Effects Predominate
- The most frequent adverse effects remain gastrointestinal (nausea, vomiting, diarrhea) occurring in 30-40% of patients, not dermatologic 3
- Dermatologic reactions represent rare adverse events compared to the primary side effect profile 1, 2
Management Approach
- If dermatologic reactions develop, consider discontinuation as this leads to resolution within weeks to months 1, 2
- For allodynia specifically, some patients experienced spontaneous improvement with continued therapy after 4 months, though this is not guaranteed 2
- The Naranjo scale scores of 5-6 (probable) indicate a clear temporal and dose-response relationship for these skin reactions 2
Important Caveats
- No specific anatomical distribution pattern has been established that would predict where reactions will occur 1, 2
- These dermatologic adverse effects are sufficiently rare that they do not appear in the primary safety profiles reported by major guideline societies 3
- The mechanism for these skin reactions remains unknown, and it is unclear whether this represents a class effect of all GLP-1 receptor agonists 2