Twenty individuals who had suffered from allergic contact dermatitis from p-phenylenediamine and had had strongly positive patch test reactions to this dye were recalled for patch testing with hair that had been dyed 24 hours previously with p-phenylenediamine. The patch test procedure was repeated in three weeks.
None of the 20 p-phenylenediamine-sensitive individuals showed any reaction to the dyed hair, either after 48 hours or at the end of three weeks.
p-Phenylenediamine-sensitive individuals can come in intimate contact with hair and furs colored with this dye without risking dermatitis since the oxidized p-phenylenediamine is not allergenic. This fact is of importance top-phenylenediamine-sensitive individuals who are hair dressers and beauticians who may be exposed to hair colored with this dye.
Reiss F, Fisher AA. Is Hair Dyed With Para-phenylenediamine Allergenic?. Arch Dermatol. 1974;109(2):221-222. doi:10.1001/archderm.1974.01630020037009