 The study team aims to conduct a double-blind, placebo-controlled, pilot study to assess the effect of prophylactic antipyretics on the immune responses and rates of fever after inactivated influenza vaccine IIV in children 12 through 35 months of age. In this pilot, 40 healthy children, 12 through 35 months of age, including some children at risk of febrile seizure, will be randomized to receive prophylactic acetaminophen or oral placebo immediately following and every 4 to 6 hours in the 24 hours after receipt of a dose of IIV. Data derived from the pilot study will be used to assess the feasibility of conducting a larger scale study. Feasibility will include assessments of the speed and ease of study recruitment and adherence to and completion of study assessments. Children will be followed for the occurrence of fever, fussiness, changes in appetite and sleep patterns, and use of medical services on the day of and day following vaccination. Antibody to influenza antigens contained in the 2013-2014 vaccine as measured by hemagglutination inhibition HAI antibody will be assessed at baseline and four weeks following vaccination. The proportions of children experiencing fever, having solicited reactions, using medical services, demonstrating a serologic response corresponding to seroprotection and seroconversion to each of the IIV antigens will be determined for groups of children receiving acetaminophen and placebo. Likewise geometric mean HAI titers GMT and corresponding 95 confidence intervals for each IIV antigen will be calculated for both vaccine groups. 