Tetanus, Diphtheria, Pertussis Vaccine (Tdap)

Medically Reviewed by Poonam Sachdev on February 20, 2024
7 min read

Tdap is a common vaccine that protects you against three serious bacterial infections: tetanus, diphtheria, and pertussis (whooping cough).

Tetanus affects your brain and nervous system and causes painful muscle spasms. Jaw spasms can make it impossible for you to open your mouth. This condition is often called "lockjaw."

Diphtheria is a very contagious infection that makes it difficult to breathe. In severe cases, it can cause heart and nerve damage and death.

Pertussis, or whooping cough, is a respiratory infection that can lead to severe breathing problems, especially in infants. Pertussis first appears like an ordinary cold, but then causes intense coughing spells. A "whoop" noise is heard when you try to take a breath after coughing.

Tdap vs DTaP

Tdap and DTaP are two vaccines that prevent the same diseases, but you get them at different times.

The DTaP vaccine is for children aged 2 months to 6 years.

The Tdap vaccine is a booster shot given at age 11 or 12 and then after every 10 years. Booster shots are extra doses you get after you have had your primary shots as a child. These make sure that you continue to be protected in adulthood. 

Other times when you may need the Tdap vaccine are:

  • If you are pregnant. You should get the vaccine near the end of each pregnancy.
  • If you are an older teen or adult who missed the booster at age 11 or 12.

You should get either the Tdap or another vaccine called Td (tetanus and diphtheria) if you get a bad burn or deep cut.

The FDA has approved two Tdap booster vaccines for teens, adults, and pregnant people: Adacel and Boostrix. Both vaccines contain antigens, which are forms of the bacteria that cause tetanus, diphtheria, and pertussis. Antigens are inactive, so they can't cause you to become sick. But they stimulate your immune system to create antibodies. These are proteins that can kill the active forms of these bacteria if you are exposed to them in the future.

Other ingredients include formaldehyde, something that naturally occurs in your body. A very small amount of formaldehyde (even less than what your own body naturally creates) is used in many vaccines to make the viruses inactive. Formaldehyde is toxic in large doses, but the amount in vaccines is too small to cause any harm.

Both vaccines have other ingredients, such as aluminum salts. These are used as adjuvants, which are substances that help you create antibodies. These have been used in vaccines since the 1930s and pose no risk to your health.



For adults and older children, the Tdap vaccine is given as a shot in the upper arm muscle. For babies and young children, the shot is usually given in the muscle on the outer thigh. You'll get the shot in your doctor's office, at a clinic, or in a pharmacy.

The doctor or nurse will clean your skin with an alcohol wipe to kill any bacteria. They'll insert the needle into your skin and press a plunger, which will deliver the vaccine solution into your muscle. Then, they'll quickly take the needle out and apply pressure to the site just in case there's any bleeding. They'll put a bandage over the area, and you'll be done.

The CDC says everyone should be vaccinated for tetanus, diphtheria, and pertussis. The Tdap vaccine is for children aged at least 7, teens, and adults.

  • Teens should get a Tdap vaccine when they are 10 or 11 years old.
  • Adults who haven't gotten a Tdap vaccine before should get one.
  • You should get a booster every 10 years. You'll either have the Tdap or a different shot called Td, which is a form of the vaccine that protects you from tetanus and diphtheria but not pertussis.
  • Your doctor may also recommend that you be vaccinated again if you get a deep cut, severe wound, or burn.




If you are pregnant, your health care provider will likely recommend you to get the Tdap vaccine sometime between the 27th and 36th weeks of your pregnancy. This allows your body to pass the antibodies on to your newborn, protecting them until they can get their first vaccine at 2 months old. This vaccine is particularly important because whooping cough is very serious for newborns and can be fatal.

If you received a booster just before your pregnancy, you will still need the vaccine in the last few weeks. This is because the pertussis vaccine won’t be as effective many months later, and your baby may not be protected.

The Tdap vaccine should not be given to children younger than 7.

You should not receive the vaccine if you have had:

  • A serious allergic reaction to any of the vaccine ingredients in the past
  • A coma or any seizures within a week of receiving a previous dose of any pertussis vaccine (such as DTaP), unless the vaccine was not the cause; Td can be used in these cases.

If you have had any of the following, talk to your doctor about whether the Tdap or Td vaccine is right for you:

  • Epilepsy or another nervous system problem
  • Guillain-Barré syndrome (GBS)
  • A history of severe swelling or pain after receiving a pertussis, tetanus, or diphtheria vaccination in the past
  • If you are moderately to severely ill (your doctor may recommend waiting to get the shot until after you recover)

What happens if you accidentally get two Tdap shots?

For most people, getting two Tdap shots close together won’t cause any harm, although they could develop more severe local reactions, such as pain, redness, or swelling at the injection site.

Like all medicines, vaccines can have side effects. However, the chance of a life-threatening reaction is small. The CDC says the dangers of developing pertussis, tetanus, or diphtheria far outweigh the risks of vaccination.

Mild side effects of Tdap may include:

  • Pain, redness, or swelling in the arm where the shot was given
  • Mild fever
  • Headache
  • Tiredness
  • Stomach upset, including nausea, vomiting, or diarrhea
  • Muscle aches

In some people, these side effects may be more intense. They may temporarily interfere with daily activities. Severe swelling of the arm has been reported in 3 out of 100 people receiving either Tdap or Td. About 1 in 250 adults who receive the Tdap vaccine develop a fever of 102 F or higher.

Although it's rare, you could have a severe allergic reaction after any type of vaccine. But the chances of this are less than one in a million doses. Signs you are having an allergic reaction include:

Seek immediate medical care if you notice any of these signs after receiving the Tdap.

Most people get their Tdap vaccine at their doctor’s office or clinic. If you’re in an emergency department or urgent care clinic because you’ve had a deep cut or bad burn, you may get the vaccine there.

Other places you can get the vaccine include:

  • Pharmacies
  • Community health clinics
  • Public health departments

Tdap vaccine cost
Under the Affordable Care Act, marketplace health plans and insurances must cover some preventative care, including the Tdap vaccine. Call your insurance company for more information.

If you are on Medicaid or you have Medicare with prescription coverage, the Tdap vaccine is covered.

Where can I get the Tdap vaccine for free?
If you are not insured and cannot afford to pay for a Tdap vaccine, there are some possible options to help you get the vaccination for free. The U.S. Department of Health and Human Services website lists federally funded centers and each state’s health department, where you can find information for free and low-cost vaccines in your area.

Being vaccinated against tetanus, diphtheria, and pertussis is vital to prevent serious illness. Tell your doctor if you didn't receive a series of vaccines as a child. Once you are up to date with those, you'll need regular follow-up boosters at least every 10 years. You might need extra doses if you have a serious cut or burn. You should also get boosters within the last few weeks of each pregnancy to protect your newborn baby.

How long after the Tdap vaccine can side effects occur?

The Tdap vaccine has few side effects. If you do have a side effect, it will usually occur within 1 day of getting the shot.

Do I need a Tdap booster to be around a baby?

If it has been more than 10 years since your last Tdap booster, you should have another dose at least 2 weeks before being in contact with a baby that has not had its first vaccine.

Does the Tdap vaccine hurt?

Vaccines don't normally cause pain during the injection. You'll probably feel a short, sharp sting as the needle enters your arm. But everyone has different pain sensations, so you might feel less or more pain than someone else.