The athlete who suffers from atopic diseases such as seasonal allergic rhinitis has an arsenal of antihistamines from which to choose for relief of symptoms. The decision to select a particular medication involves consideration of its efficacy and its side effects. Many of the standard antihistamines have sedative side effects which render them undesirable for use by athletes during competition. For example, a survey of studies suggests that some of these medications may compromise the performance of psychomotor skills important to the athlete (e.g. reaction time and visual discrimination). The newer, nonsedating antihistamines are equal to the standard agents in efficacy and comparable with placebo in central nervous system effects. Thus, psychomotor performance is not adversely affected by the newer antihistamines. Despite their widespread use, the effects of treatment with antihistamines on exercise performance (e.g. metabolic responses and time to exhaustion) have scarcely been addressed. The few studies available indicate that single oral administrations of antihistamines neither compromise nor enhance exercise performance or tolerance in asymptomatic individuals. Yet the research conducted has not examined the effects of antihistamine ingestion on exercise performance in symptomatic individuals. Whether treatment with an antihistamine would improve exercise performance relative to nontreatment in symptomatic, atopic athletes remains to be determined. Whereas there is a dearth of information on the effects of antihistamine medications on exercise performance, there is growing evidence that pretreatment with antihistamines may prevent or attenuate some exercise-induced histamine-mediated disorders such as urticaria, pruritus, anaphylaxis and gastrointestinal bleeding. A survey of studies suggests that prophylactic treatment with antihistamines may increase tolerance to exercise in individuals susceptible to these disorders.