Dyes and preservatives in oral antihistamines

Antihistamines are commonly used in the treatment of urticaria. Some antihistamines contain dyes and preservatives which have themselves been shown to produce or exacerbate urticaria; the presence of these substances is not indicated in the usual formularies and a list of commonly prescribed antihistamines is presented, detailing the azo dyes, other dyes and preservatives contained therein.