Sensitivity to para-phenylenediamine and intolerance to hydrochlorothiazide

para-Phenylenediamine (PPD) is a contact allergen that cross-reacts with a variety of medications, including thiazide diuretics and sulfonamides. We present the case of a 52-year-old African American atopic woman who came for evaluation of a severe eyelid dermatitis and recurrent outbreaks of acneiform (follicular-based) pruritic papules on her face, chest, and back. These symptoms presented after the patient was started on hydrochlorothiazide for hypertension. The patient also reported a history of eyelid dermatitis associated with "black hair dye." Patch testing revealed a positive reaction to para-phenylenediamine (1+) and Disperse Blue 106 (1+). It was suspected that the patient might be demonstrating cross-reactivity to hydrochlorothiazide and a flare-up reaction of the eyelid dermatitis. After her cardiologist changed her blood pressure medication, the patient's eyelid dermatitis and eruption cleared. This case highlights the impact of PPD sensitization on the medical care of a patient with hypertension and the importance of choosing safer PPD-free alternatives and minimizing PPD exposures.