Triethanolamine allergy inadvertently discovered from a fluorescent marking pen

Triethanolamine is used as an emulsifier in many topical preparations and is an infrequent cause of contact allergy. We report a case of a woman with a contact allergy to triethanolamine inadvertently discovered when she had a reaction to a triethanolamine-containing fluorescent marking pen that was used in patch testing. On further investigation, triethanolamine was found to be in several of her topical products.