Since the majority of children do not experience any fever after vaccination, the use of fever reducers such as acetaminophen (Tylenol) or ibuprofen (Motrin) are not routinely recommended for everyone after shots. If fever reducers are used for all children every time they get their shots, the majority of children would be taking these medications unnecessarily because they would not have fever reaction anyway.

On the other hand, it is always a good idea to have these medications at home if your child has received vaccination recently. You don't want to be in the position of having a child with a fever in the middle of the night and having to drive all over town to find a twenty-four-hour pharmacy, looking for that one precious bottle of acetaminophen.

While the fever triggered by vaccination is never harmful, you can certainly give your child fever reducers to make him more comfortable. It is very important to administer the correct dosage of the fever reducer. Calculate the dosage using your child's weight, because children come in all sizes. Using the age alone to calculate the dose can result in underdosing or overdosing. Follow the instruction on the medication packaging carefully, and do not give the medication more often than recommended. Typically acetaminophen (Tylenol) can be given every four hours, and ibuprofen (Motrin) can be given every six hours. It is not a good idea to use both acetaminophen and ibuprofen at the same time. While both medications can be administered safely together, giving both can make it more difficult to keep track of dosing and makes the possibility of overdosing more likely. Call your doctor or a nurse if you are unsure of how much fever reducer to administer.

Developing a relatively high fever is not unusual after vaccination, but a persistent fever should not occur with immunization. A temperature of up to 102°F is not worrisome, but if the fever lasts for more than two days, there might be another reason why your child is having a high temperature. While vaccines are designed to protect your child, they do not protect her from all types of infections. It is entirely possible to get sick from another type of germ (such as croup or a bladder infection) around the time that the vaccines are given. A fever that lasts more than forty-eight hours is the most likely indicator that your child may be sick from something else. Call your doctor if a fever does not go away two days after immunization. For more information on fever and how to manage it, please refer to Chapter 3, on vaccine reaction.