This 15 year old boy has just returned from a holiday in Thailand. He had a beach tattoo undertaken 10 days ago – he has had persisting itchy red areas where the tattoo had been applied.
The likely cause of his reaction to the beach “henna tattoo” is an allergic contact dermatitis to the black dye chemical paraphenylene diamine. Although the tattoo solution does contain some henna, this is much less likely to be the sensitiser.
The reaction will settle with the use of a topical steroid, he is now sensitised to PPD, and should he use a PPD containing hair dye in the future he will have a reaction to this. PPD allergic individual may also react to some azo clothing dyes, PABA containing sunscreens, amine local anaesthetics (benzocaine and procaine) sulphonamides and sulphone drugs.