Prophylactic use of acetaminophen in children vaccinated with diphtheria-tetanus-pertussis.

BACKGROUND: The present randomized non-blind trial was conducted to clarify the effect of analgesics on febrile responses of booster diphtheria-tetanus-whole cell pertussis (DTP) vaccine in 15-20 months old infants. METHODS: A total of 270 healthy infants were randomized to receive acetaminophen (10 mg/kg) along with DTP vaccine (group 1), 2 hours after vaccination (group 2), and after the appearance of febrile reactions or irritability following vaccination (group 3, control). In addition to study medication, if the axillary temperature was higher than 38 degrees C or if the infant seemed to be irritable, the parents were told to give acetaminophen (10 mg/kg) and record on a diary card. Vaccinees were monitored for local and systemic reactions. RESULTS: The incidences of local swelling, pain and erythema were not significantly different among the 3 groups. No difference was observed in the incidence of systemic reactions including febrile responses, irritability, anorexia, and vomiting among the 3 groups during the 7 days after vaccination. Of the infants, 45.1%, 46.7% and 51.9% manifested fever (axillary temperature > or =38 degrees C) within 24 hours after the vaccination in groups 1, 2 and 3, respectively (P>0.05). The second dose of acetaminophen was less in the control group than in the prophylactic groups (P=0.009). CONCLUSIONS: Administration of acetaminophen along with DTP vaccine or 2 hours after vaccination does not affect the occurrence of febrile responses following booster vaccination. Unnecessary use of analgesics should be prevented.