Getting diphtheria, tetanus, or pertussis disease is much riskier than getting DTaP vaccine. However, a vaccine, like any medicine, is capable of causing serious problems, such as severe allergic reactions. The risk of DTaP vaccine causing serious harm, or death, is extremely small.

Mild Problems (Common)

• Fever (up to about 1 child in 4)
  
• Redness or swelling where the shot was given (up to about 1 child in 4)
  
• Soreness or tenderness where the shot was given (up to about 1 child in 4)
  

These problems occur more often after the 4th and 5th doses of the DTaP series than after earlier doses. Sometimes the 4th or 5th dose of DTaP vaccine is followed by swelling of the entire arm or leg in which the shot was given, lasting 1-7 days (up to about 1 child in 30).

Other mild problems include:

• Fussiness (up to about 1 child in 3)
  
• Tiredness or poor appetite (up to about 1 child in 10)
  
• Vomiting (up to about 1 child in 50)
  

These problems generally occur 1-3 days after the shot.

Moderate Problems (Uncommon)

• Seizure (jerking or staring) (about 1 child out of 14,000)
  
• Non-stop crying, for 3 hours or more (up to about 1 child out of 1,000)
  
• High fever, over 105°F (about 1 child out of 16,000)
  

Severe Problems (Very Rare)

• Serious allergic reaction (less than 1 out of a million doses)
  
• Several other severe problems have been reported
  after DTaP vaccine. These include:
  
  • Long-term seizures, coma, or lowered consciousness
    
  • Permanent brain damage.
    These are so rare it is hard to tell if they are caused
    by the vaccine.
    

Controlling fever is especially important for children who have had seizures, for any reason. It is also important if another family member has had seizures. You can reduce fever and pain by giving your child an aspirin-free pain reliever when the shot is given, and for the next 24 hours, following the package instructions.