Antihistamines are used as a treatment for allergies but cause sedation as a side effect. This sedation can be so severe that it interferes with patients daily functioning such as driving a vehicle. This chapter gives an overview of the effects of numerous antihistamines on driving performance as assessed in a standard highway driving test. When investigating the effects of an acute administration of the therapeutic dose, many antihistamines cause driving impairment comparable or larger than the effect of 0,5 mg/ml alcohol (i.e. Hydroxizine, emedastine, diphenhydramine, clemastine, triprolidine, mizolastine, mequitazine, dexchlorpheniramine cr). However this does not mean that the other antihistamines are free of sedating effects. Driving i...