Table 1.

Chemicals that cross-react with PPD

Chemical	Product
Para-aminobenzoic acid	Sunscreens
Sulfonamides, sulfonylureas	Medications
Para-toluenediamine sulfate	Semipermanent hair dyes
Azo dyes	Clothes, ballpoint pen ink, shoes
Benzocaine, tetracaine, procaine	Local anesthetics
Para-aminosalicylic acid	Antibiotics

Abbreviation: PPD, para-phenylenediamine.