CD13 A case of propylene glycol allergic contact dermatitis associated with Soolantra

Abstract

Propylene glycol (PG) is a common excipient found in numerous topical, oral and injectable medications, as well as in cosmetics and personal care products. Although PG is considered a weak sensitizer, it can elicit clinically significant reactions, and reports of allergic contact dermatitis due to PG in prescription topical therapies remain relatively uncommon. A 48-year-old woman presented to dermatology with a 4-year history of an erythematous, burning facial rash localized predominantly to the central cheeks, chin and perinasal area. She presented with facial erythema, for which her general practitioner had prescribed Soolantra® cream (ivermectin 1%) to treat a presumed diagnosis of rosacea. Over subsequent months, she developed increasing erythema, oedema and pruritus in the treated areas. The patient had a past history of hay fever and a family history of eczema in her brother. She had not recently changed her skincare or cosmetic products, using ‘Kiehl’s face wash’, but reported a previous flare following the application of ‘Kiehl’s calendula cream’. She was a waitress but reported no occupational or hobby exposures to common allergic contact dermatitis precipitants. The patient underwent standardized patch testing. Additional testing with the patient’s own products including Soolantra cream, Kiehl’s calendula cream, and Kiehl’s calendula wash was conducted. She demonstrated a strong (+2 reaction) to propylene glycol and Kiehl’s calendula cream, and a +1 reaction to Soolantra cream. Based on the clinical course and patch test findings, a diagnosis of allergic contact dermatitis to PG in Soolantra cream was made. Of note, Kiehl’s calendula cream and Lancome foundation also contain PG in their listed ingredients. Allergic contact dermatitis to PG can occur following use of Soolantra cream for rosacea. Clinicians should maintain a high index of suspicion for excipient allergy in patients presenting with new-onset dermatitis at application sites, and patch testing remains the gold standard for diagnosis.