Abstract
Summary The addition of the stimulant, ephedrine hydrochloride (15 mg), to the antihistamine, chlorpheniramine maleate (10 mg) is shown significantly to reduce the adverse drowsy effects of the latter upon various components of human performance. Auditory vigilance — a test of long-term attentiveness — is shown particularly to benefit from the addition of ephedrine. Whilst ephedrine does not aid simple reaction speed, it does reduce the pausing in serialchoice performance, indicative of a drowsy state, which otherwise occurs under chlorpheniramine alone.