 [ Symptoms ] i am very concerned i noticed today my urine if very dark and red or brown maybe blood  the only recent change i have epericenced would be a hep b vaccine shot last week i have no injuries and this is a very sudden change [ Disease ] i have to ask why you want to do this if we are treating an infant for pain or fever i would recommend the tylenol infant drops only due to the fact that aspirin can increase the risk of reye is syndrome i would not consider chewable 81 milligram baby aspirin infants and children are not little adults  so you need to be very careful when it comes to medication