[Skin irritation caused by propylene glycols]

Area of Science:

• Dermatology
• Toxicology
• Cosmetic Science

Context:

• Propylene glycol (PG) is a common ingredient in food, medicine, and cosmetics due to its solvent, humectant, antiseptic, and preservative properties.
• Skin reactions, including eczematous responses, can occur with PG exposure, presenting as either irritant or allergic contact dermatitis.
• Interpreting positive patch test reactions to PG can be challenging, necessitating further investigation to confirm allergic sensitization.

Purpose:

• To evaluate the diagnostic utility of patch testing for propylene glycol.
• To differentiate between irritant and allergic contact dermatitis reactions to propylene glycol.
• To assess the clinical relevance of positive patch tests through provocation tests.

Summary:

• Patch testing with 100% propylene glycol identified both irritant and allergic reactions in patients.
• Oral provocation tests confirmed allergic contact dermatitis in a subset of patients with positive patch tests.
• Skin reactions to propylene glycol are infrequent, but dermatologists should consider PG allergy, especially given its use in topical medications.

Impact:

• Highlights the importance of careful interpretation of patch test results for propylene glycol.
• Provides evidence for confirming propylene glycol allergy through provocation testing.
• Informs dermatologists about the potential for propylene glycol allergy in patients using topical preparations containing this ingredient.