Do GLP-1 Receptor Agonists Cause Fever Blisters?
No, GLP-1 receptor agonists do not cause fever blisters (herpes simplex labialis). There is no evidence in the medical literature linking GLP-1 receptor agonists to herpes simplex virus reactivation or the development of fever blisters.
Evidence Review
Dermatologic Effects of GLP-1 Receptor Agonists
The available evidence demonstrates that GLP-1 receptor agonists have beneficial anti-inflammatory effects on skin conditions, not adverse effects like fever blisters:
GLP-1 agonists improve inflammatory skin diseases including psoriasis, hidradenitis suppurativa, acanthosis nigricans, and Hailey-Hailey disease through their anti-inflammatory mechanisms 1, 2.
The anti-inflammatory pathways affected by GLP-1 receptor agonists include downregulation of TNF-α, IL-23, IL-17, IL-22, and NF-κB—cytokines critical to inflammatory skin conditions 1, 3.
Clinical case series have documented improvement in refractory dermatologic conditions following GLP-1 therapy initiation, not worsening or new skin lesions 1.
Known Adverse Effects
The documented adverse effects of GLP-1 receptor agonists are well-characterized and do not include fever blisters:
Gastrointestinal effects are the most common adverse events: nausea, vomiting, diarrhea, abdominal pain, and delayed gastric emptying 4, 5.
Injection site reactions may occur with subcutaneous formulations, including local hypersensitivity, but these are distinct from viral-mediated fever blisters 5.
Other documented adverse effects include pancreatitis, biliary disease, renal complications from severe GI losses, and hypoglycemia when combined with sulfonylureas or insulin 5.
Important Clinical Context
Fever blisters are caused by herpes simplex virus (HSV) reactivation, typically triggered by:
- Fever or systemic illness
- Stress
- Immunosuppression
- Sun exposure
- Local trauma
GLP-1 receptor agonists do not cause immunosuppression—in fact, they modulate immune function in an anti-inflammatory direction without compromising antiviral immunity 6, 2.
Clinical Recommendation
If a patient on GLP-1 therapy develops fever blisters, investigate alternative causes:
- Recent viral illness or fever (the most common trigger) 7
- Psychological or physiologic stress
- Sun exposure or local trauma to the lips
- Concurrent immunosuppressive medications
The fever blisters should be managed according to standard HSV treatment protocols and are not an indication to discontinue GLP-1 therapy.