The intervention group had better knowledge of precautions related to taking additional acetaminophen ( usual care @ % , @ % confidence interval -LSB- CI -RSB- = @ % to @ % vs. intervention @ % , @ % CI = @ % to @ % ; difference = @ , @ % CI of difference = @ to @ ) and knowledge of side effects ( usual care median = @ , interquartile range -LSB- IQR -RSB- @ to @ vs. intervention median = @ , IQR = @ to @ ; p < @ ) .