Between 1962 and 1965, 78 cases of allergy to topically administered medicaments were documented in the author's private practice. In 60 of the 78 patients the allergy had been responsible for causing or aggravating a dermatitis. Antimicrobials, antihistamines, and anesthetics were the most prominent allergens with neomycin being the single most frequent sensitizer. Topically administered medicaments that commonly sensitize should be avoided unless their use provides clear-cut therapeutic benefits.
Epstein E. Allergy to Dermatologic Agents. JAMA. 1966;198(5):517-520. doi:10.1001/jama.1966.03110180061019