Antihistamines (H1 receptor antagonists) are commonly found in over-the-counter and prescription medications used for motion sickness, control of allergy-related itching, and cough and cold palliation and used as sleep aids (Table II–9). Acute intoxication with antihistamines results in symptoms very similar to those of anticholinergic poisoning. H2 receptor blockers (cimetidine, ranitidine, and famotidine) inhibit gastric acid secretion but otherwise share no effects with H1 agents, do not produce significant intoxication, and are not discussed here. Common combination products containing antihistamines include Actifed, Allerest, Contac, Coricidin, Dimetapp, Dristan, Drixoral, Excedrin PM, Nyquil, Nytol, Pamprin, PediaCare, Tavist, Triaminic, Triaminicol, Unisom Dual Relief Formula, and Vicks Pediatric Formula 44.