CONCOMITANT USE OF ANTIHISTAMINES WITH ALCOHOL, TRICYCLIC ANTIDEPRESSANTS, BARBITURATES, OR OTHER CNS DEPRESSANTS MAY HAVE AN ADDITIVE EFFECTS. MAO INHIBITORS PROLONG AND INTENSIFY THE EFFECTS OF ANTIHISTAMINES & MAY CAUSE HYPERTENSIVE REACTIONS, INCLUDING HYPERTENSIVE CRISES. THE ANTIHYPERTENSIVE EFFECTS OF METHYLDOPA, MECAMYLAMINE, RESERPINE, AND
VERATRUM ALKALOIDS MAY BE REDUCED. BETA-ADRENERGIC BLOCKING AGENTS MAY ALSO INTERACT.