• To determine the efficacy of acetaminophen prophylaxis for prevention of post-vaccination fever (temperature 38ºC) following routine childhood immunizations.
  

• To determine whether use of prophylactic acetaminophen reduces the infant’s medical utilization, parents’ time lost from work, and sleep lost by parents and infant within a day of vaccination.
  

Post-vaccination fever occurs in up to 40% of infants receiving routinely recommended childhood vaccinations. Although serious events are rare, post-vaccination fever causes discomfort for the child, can lead to medical utilization, can rarely result in febrile seizure, and can cause a working parent to miss time from their job to care for a febrile infant who cannot attend day care. The benefits of acetaminophen prophylaxis for infants receiving current vaccinations, in terms of reduction of discomfort for the child, improvement of quality-of-life indicators for the parent, or reduction of medical utilization, have not been measured. This randomized, blinded, placebo-controlled trial will assess the efficacy of prophylaxis with acetaminophen in prevention of fever following routine childhood immunizations.

Inclusion Criteria:

1. Child is a current Group Health enrollee.
2. Child will be seen at a Group Health clinic for a Well Child visit that is expected to include 2 or more vaccines after 6 wks and before 10 months of age.

Exclusion Criteria:

1. If child was born at less than 36 weeks of gestation, the child is not eligible until 4 months of age or older.
2. If the child’s birth weight was less than 5.5 pounds (2500 grams), the child is not eligible until 4 months of age or older.