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The Diphtheria/Tetanus/Pertussis Vaccine

Tdap Vaccination

The Tdap vaccine is used to protect against, tetanus (lockjaw), diphtheria, and pertussis (whooping cough).

According to the Centers for Disease Control and Prevention (CDC), these diseases are caused by bacteria. The number of cases of tetanus and diphtheria has dropped by about 99 percent and pertussis by about 80 percent since the Tdap vaccine started to be administered.

There are actually four separate vaccines used to protect against these diseases:

  • DTaP
  • DT
  • Tdap
  • Td

The names of the vaccines show what they contain. Capital letters mean there is a full dose of the vaccine for that illness. Lower case letters mean there is a reduced dose. Therefore Tdap contains a full dose of tetanus toxoid vaccine. However, it only contains a reduced dose of diphtheria toxoid and pertussis vaccines.

DTap and DT are used for children under 7. Tdap and TD are used for older children and adults.

Getting Vaccinated

The type of Tdap vaccine you will receive depends on your age.

DTaP and DT

DTaP protects against all three diseases. The CDC recommends that all children receive five doses of this vaccine. These are administered at the ages of:

  • 2 months
  • 4 months
  • 6 months
  • 15 to 18 months
  • 4 to 6 years

DTaP is not licensed for older children, adolescents, or adults. DT is used as a substitute when children can’t handle pertussis vaccination.


Tdap is the primary vaccine used for adolescents and adults. All adolescents should get this vaccine – ideally at age 11 or 12. Adults should also get this vaccine if they have never received it.

This vaccine may also be given to children between the ages of 7 and 10 who are not completely immunized against pertussis. 


The Td vaccine is used as a booster. Adults should get this vaccine every 10 years.

Pregnant Women

Pregnant women who have never been vaccinated with Tdap should be vaccinated after 20 weeks gestation. Pertussis can pose a severe risk for infants. Adults who will be around young infants should also get a Tdap vaccine.

Who Should Not Get Vaccinated?

Most people should be getting tetanus vaccines or boosters approximately every 10 years. However, there are certain people who should not get these vaccines. These include:

  • people who had severe allergic reaction to past doses of Tdap, DTaP, DT, or Td
  • people who are allergic to vaccine components
  • people who had a coma or seizures within 7 days of receiving DTP or DTaP vaccines
  • anyone who is currently moderately to severely ill 

There are also additional factors that affect the risk of getting Tdap. Discuss the risks of vaccination with your doctor if you:

  • have epilepsy or other nervous system diseases
  • had severe swelling from past doses of DTP, DTaP, DT, Td, or Tdap
  • have had Guillain-Barre syndrome (GBS)

Potential Side Effects

Severe side effects from the Tdap and Td vaccines are uncommon. However, these vaccines do hold some risk. Possible side effects include:

  • soreness or swelling where the shot was given
  • fever
  • headache
  • body ache
  • fatigue
  • vomiting
  • high fever

In very rare cases these vaccines can cause fainting or seizures. Another rare side effect is severe swelling in the arm. This can limit movement. Severe allergic reactions are possible but extremely rare. 

Content licensed from:

Written by: Amy Boulanger
Medically reviewed on: Nov 24, 2014: George Krucik, MD, MBA

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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