There are several things you can do to protect your child from suffering a reaction to a vaccine. First, make sure he's healthy. Most experts don't recommend vaccinating your child if he has a fever or any illness more serious than a common cold.
If your child has any allergies, he may need to avoid certain vaccines. Allergies to cow's milk or peanuts aren't an issue when it comes to vaccines. But a child who is allergic to gelatin may need to avoid the MMR and chicken pox vaccines, which are made with gelatin. And a child who is allergic to yeast shouldn't receive the hepatitis B shot, which contains yeast.
Tell your doctor if your child has ever had an allergic reaction to an antibiotic. Some vaccines are made with the antibiotics streptomycin, neomycin, and polymyxin B. If your child is allergic to penicillin, there shouldn't be any problem.
Also tell your doctor if your child has an egg allergy. If the egg allergy is serious, your doctor will probably advise against a flu shot, which is made with egg protein. The yellow fever vaccine, given to those traveling to developing countries, also contains egg protein. Kids who have mild reactions after eating eggs (such as stomach upset) may be able to get these vaccines.
Until recently, children with egg allergies were advised against receiving the MMR vaccine, which is made with chick embryo cells. But recent studies have established that kids who are allergic to eggs are not adversely affected by the MMR vaccine. If your child has an egg allergy, talk to your doctor about whether it's safe for your child to get the MMR vaccine.
Unfortunately, doctors can't predict with any accuracy which few children will experience an adverse reaction to a vaccine. If your child has had a severe reaction to a particular vaccine in the past, be sure to bring this to your doctor's attention.
Mild vaccine reactions, such as low fever and soreness or swelling at the injection site, are quite common. If your child has had a mild reaction to a previous vaccine, ask your doctor if it's okay to give him a pain reliever before he gets his shot. Ibuprofen (if he's 6 months or older) or acetaminophen can minimize symptoms and make him more comfortable.