Topical diphenhydramine toxicity.

This paper will review an acute onset of mental confusion associated with hallucinations secondary to vigorous administration of topical Caladryl lotion and Benadryl spray in an 8-year-old boy with chickenpox. The article discusses the toxicity of both oral and topical diphenhydramine use, along with the differentiation of varicella encephalitis from diphenhydramine toxicity. Delirium can be described as an acute clouding of consciousness associated with visual and tactile hallucinations, disorientation, and misperceptions. In a child who is already suffering from an infectious illness, encephalitis must be high on the list of the physician's differential diagnosis. The physician, however, must never overlook ingestions, even from topical, over-the-counter medications. The case described illustrates this point. Although this appears to be the fourth case report on this subject, the diagnosis was partially obscured by the fact that the local pharmacist could not find any documented cases despite a computer search of diphenhydramine toxicity at the time of admission and the report of only one or two cases by the Parke-Davis pharmacist.