Common Vaccine Reactions
The vaccines available today are a lot less likely to cause any side effects than those administered generations ago. Still, it is possible for some reaction to occur in a minority of children. The vast majority of these reactions are minor and brief. It is exceedingly rare for a vaccine-triggered reaction to require medical intervention.
Fever
Fever is by far the most common vaccine-related reaction in children. It can happen with the first set of vaccinations, or it can happen with subsequent booster shots. Children of all ages are susceptible to this reaction. It is estimated that less than 10 percent of children receiving vaccinations will get a fever. The number may be higher or lower, depending on the vaccine.
Alert!
Many infants become irritable after certain vaccines, particularly with the combination vaccine that protects against tetanus and the whooping cough (DTaP). This reaction is not expected to be prolonged. If your child remains irritable for more than three hours after the vaccination or cries continuously for more than an hour, contact your doctor immediately.
Regardless of how high the temperature, the fever usually doesn't last for more than three days. If it does, call your doctor for an appointment to have your child evaluated. There might be another cause for the fever.
If your child's temperature is less than 104ºF and transient (or changing), you can administer acetaminophen (Tylenol) to your child to make him more comfortable. Please refer to Chapter 5 for additional advice on fever management.
Local Skin Reaction
Skin redness at the site of injection and rash are common vaccine reactions. They generally do not cause any discomfort for the child, and most of them disappear in less than three days.
However, the vaccine that protects against tetanus and whooping cough (DTaP) is notorious for its tendency to cause a large, red bump under the skin at the injection site. This reaction is especially common after the fourth or fifth vaccination in the DTaP series (which is usually given at the time your child enters kindergarten).
If your child develops a mildly tender bump at the site of a vaccination, don't panic. The vast majority of cases are not caused by infection or a serious allergic reaction. The area of redness may be quite large (larger than an inch is not unusual), but the pain is generally minor. The discomfort should not prevent your child from using the arm or the leg. If the pain is intense or if it prevents your child from walking or using his arm, you should seek medical attention.
