This study was designed to investigate the efficacy of a decongestantantihistamine preparation in combination with antibiotic treatment of acute otitis media. The effectiveness of a new Dimetapp ® (DIM) preparation was assessed in comparison with each of its components (brompheniramine maleate [BPM] and phenylephrine hydrochloride [PEH]) as well as a placebo (PL) vehicle in the treatment of acute otitis media. In a randomized double blind study, 98 children were treated in the emergency department or outpatient medical clinics at Children's Hospital of Michigan with amoxicillin and either DIM, BPM, PEH, or PL. They were evaluated at two weeks by clinical examination, pneumatoscopy, and tympanometry. Fifty-eight patients (59%) continued to have evidence of fluid in the middle ear. These patients were continued on the test medications for another two weeks and then reevaluated. There were significant differences between the treatment groups (DIM, BPM, and PEH) and the control PL group; the patients receiving Dimetapp ® or placebo fared better than those receiving BPM or PEH. However, there was no difference in the overall response between Dimetapp ® and placebo. Antihistamine-decongestant therapy does not appear to be necessary in the treatment of acute otitis media in children.