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Diphtheria-Tetanus-Pertussis Vaccine

By William D. Surkis, MD, Clinical Associate Professor of Medicine; Director, Internal Medicine Residency Program, Jefferson Medical College; Lankenau Medical Center ; Jerome Santoro, MD, Clinical Professor of Medicine; Chief, Department of Medicine, Jefferson Medical College; Lankenau Medical Center

The diphtheria, tetanus, and pertussis vaccine is a combination vaccine that protects against these three diseases:

  • Diphtheria usually causes inflammation of the throat and mucous membranes of the mouth. However, the bacteria that cause diphtheria produce a toxin that can damage the heart, kidneys, and nervous system. Diphtheria was once a leading cause of death in children.

  • Tetanus (lockjaw) causes severe muscle spasms, which result from a toxin produced by bacteria. The bacteria usually enter the body through a wound.

  • Pertussis (whooping cough) is a very contagious respiratory infection that is particularly dangerous to children younger than 2 years old and to people who have a weakened immune system.

The vaccine has two forms: DTaP for children under 7 years and Tdap for adolescents and adults. Tdap has lower doses of diphtheria and pertussis vaccine, indicated by the lower case d and p. There is also a vaccine that contains only the tetanus and diphtheria components (tetanus-diphtheria vaccine).


The diphtheria-tetanus-pertussis vaccine is given as an injection into a muscle. Five injections are given: typically at age 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years.

Because pertussis is becoming more common among adults, a booster is recommended at age 11 to 12 years to be followed by a tetanus-diphtheria booster every 10 years.

Adults who missed the series of vaccinations given during childhood should get it as adults. If adults did not receive Tdap at age 11 to 12 years or are unsure about whether they were vaccinated, doctors give them one dose of Tdap. Pregnant women are given a dose of Tdap during each pregnancy.

Side Effects

The injection site may become sore, swollen, and red. Serious side effects are rare. They include high fever, inconsolable crying, seizures, and a severe allergic reaction.

Serious side effects usually result from the pertussis part of the vaccine. If they occur, the pertussis vaccine is not used again. A vaccine against diphtheria and tetanus may be used instead to complete the vaccination series. The vaccine is not repeated if seizures or other signs of brain malfunction occur within 7 days after the vaccine is given.