OBJECTIVETo determine whether an antihistamine-decongestant combination (ADC) is superior to placebo in temporarily relieving symptoms of upper respiratory tract infection (URI) in preschool children.DESIGNRandomized, double-blind, placebo-controlled trial.SETTINGFour pediatric offices in the Seattle, Wash, area.PARTICIPANTSChildren 6 months through 5 years of age with a URI of less than 7 days' duration.METHODSChildren were randomly assigned to receive an ADC (brompheniramine maleate-phenylpropanolamine hydrochloride) or placebo as needed for URI symptoms. Two hours after each dose of study medication, changes in the child's runny nose, nasal congestion, cough, and sleep status were assessed by means of a standardized questionnaire.RESULTSA total of 175 responses were recorded for 59 patients. There were no statistically significant differences in symptom improvement between the ADC and the placebo group (runny nose, p = 0.48; nasal congestion, p = 0.94; cough, p = 0.66). However, the proportion of children asleep 2 hours after receiving the ADC was significantly higher than the proportion receiving placebo (46.6% vs 26.5%; p = 0.01). Results were unchanged after control for the correlated nature of repeated responses, age, symptom duration, use of acetaminophen, time that the medication was given, and parental desire for medication.CONCLUSIONSThe ADC was equivalent to placebo in providing temporary relief of URI symptoms in preschool children. However, the ADC did have significantly greater sedative effects than did placebo.