Motion sickness drugs often make a person drowsy and less alert. In fact, one motion sickness drug, the antihistamine diphenhydramine Some Trade Names
BENADRYL
NYTOL
SOMINEX
, is the active ingredient in most OTC sleep aids. Anyone who performs an activity that requires alertness or concentration, including driving, should not take a motion sickness drug. A motion sickness drug should not be taken with alcohol, sleep aids, tranquilizers, or other drugs that also cause drowsiness and decrease alertness.
Other side effects of antihistamines are less common (see Over-the-Counter (OTC) Drugs: Antihistamines). Infants and very young children may become agitated and should not be given a motion sickness drug except under a doctor's supervision. Too high a dose in a young child could lead to hallucinations or even seizures, which may be fatal.