Tetanus, diphtheria, and pertussis (Tdap) are infectious bacterial diseases. Without treatment, they can lead to severe complications and may be fatal. The Tdap vaccine protects against all three diseases. Tdap side effects are usually mild.

The Tdap vaccine is highly effective. Since the introduction of vaccines, cases of diphtheria and tetanus have dropped by 99%, while cases of pertussis have dropped by 80%.

Doctors can give Tdap as a primary immunization or as a booster vaccine, meaning it “tops up” the immunity a person already has to an illness.

In this article, we will discuss what the Tdap vaccine is, how safe it is, who should get it, and possible side effects.

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Tdap is a booster vaccine. It protects people from the following illnesses.


Tetanus is an infectious disease due to bacteria in soil and feces. These microbes can enter the body through cuts and wounds. When they begin to multiply, they produce a toxin that causes painful muscle contractions and spasms.

These contractions cause lockjaw, a condition that makes it hard to open the mouth or to swallow. It can also block the airways, making it difficult to breathe.

Other symptoms include:

Tetanus is fatal in 10–20% of cases.


Diphtheria is a contagious bacterial disease that spreads through contact with droplets from coughing or sneezing. It can also spread through contact with skin lesions, mucus, or saliva.

The symptoms can include:

  • a thick, gray coating at the back of the throat
  • sore throat
  • weakness
  • fever
  • swollen glands
  • difficulty breathing
  • heart failure
  • nerve damage
  • paralysis

Diphtheria can be fatal.


Pertussis, or whooping cough, is a highly contagious respiratory disease that often starts with mild, cold-like symptoms. After 1–2 weeks, the symptoms become more distinctive and include:

  • uncontrollable, intense coughing fits, followed by a “whoop” noise as a person inhales
  • vomiting after coughing fits
  • exhaustion

The symptoms can make it difficult to breathe, eat and drink. They can last up to 10 weeks and take a long time to go away fully.

Pertussis is particularly serious in babies and young children under 12 months of age. It can lead to complications, such as brain damage, convulsions, and pneumonia. And while the risk is lower for teenagers and adults, it can still cause serious complications.

The Tdap vaccine is different from the (diphtheria, tetanus, and pertussis) DTaP vaccine. They both protect against the same three diseases, but they have different dosages and uses.

The Tdap and DTaP vaccines both work by exposing the body to a very small amount of inactivated toxins that tetanus, diphtheria, and pertussis bacteria produce. This teaches the immune system how to respond to these infections.

Doctors administer five full-strength doses of the DTaP vaccine to children between the ages of 6 weeks and 6 years old. The ages they typically get the doses are:

  • 2 months old
  • 4 months old
  • 6 months old
  • 15–18 months old
  • 4–6 years old

By contrast, healthcare professionals administer the Tdap vaccine as one shot, usually every 10 years. This vaccine contains lower doses of diphtheria and pertussis and maintains and boosts the immunity that someone has already built up.

Doctors can also use Tdap for adults who have never received any immunizations for these diseases before.

However, the Tdap vaccine does not guarantee that someone will not get any of the illnesses it protects against. However, it reduces the chances of contracting them. It also reduces the length of these illnesses and the severity of the symptoms.

Learn which vaccines children need and at what ages.

The Tdap vaccine is suitable for adults, teenagers, and almost all children aged over 7 years. Getting it can protect 95 out of 100 individuals from pertussis, diphtheria, and tetanus for 10 years, although its protection decreases over time.

Doctors advise that adolescents have their first dose of Tdap between the ages of 11 and 12 years. An adult who has never had the Tdap vaccine before can get it at any time. In certain situations, doctors can give this vaccine to children as young as 7 years old.

Even if someone has already had one of the three diseases, they should still get regular Tdap shots. Recovering from one of these illnesses does not guarantee lifelong immunity.

The CDC recommends that adults get a Tdap shot every 10 years. If someone has had a severe wound or burn, and it has been at least 5 years since their last Tdap, they should receive a Tdap shot. This is because there is a higher risk of bacteria entering the wound.

Mild illnesses, such as colds, do not require a person to delay getting the Tdap vaccine. However, people with moderate to severe illnesses should wait until they recover.

The Tdap vaccine is very safe. This vaccine has undergone years of rigorous testing by the Food and Drug Administration (FDA). This agency and the Centers for Disease Control and Prevention (CDC) continuously monitor its safety and effectiveness.

The Tdap vaccine is also safe for people taking prescription medication. However, there are some individuals who may not be suitable for the vaccine. This includes those who:

  • are prone to seizures or have a nervous system condition, such as epilepsy
  • have Guillain-Barré syndrome
  • have experienced an allergic reaction after a previous dose
  • are allergic to any of the vaccine’s ingredients
  • have been in a coma or experienced decreased consciousness, 7 days after a previous dose

People undergoing chemotherapy or radiation treatment also should not get Tdap until their treatment is complete.

To deliver the Tdap vaccination, a healthcare professional will inject the vaccine into a muscle, usually in the arm or thigh. They will do this using a hypodermic needle. An individual may experience a quick, sharp pinching sensation during the procedure.

Health professionals administer the Tdap vaccine at the same time as other vaccines.

The side effects of Tdap are usually mild. Not everyone experiences them. If they occur, they may include:

  • tenderness or swelling at the location of the shot
  • swollen glands
  • headache
  • tiredness
  • stomachache
  • mild fever
  • nausea
  • vomiting
  • diarrhea
  • chills
  • irritability

Side effects can last for 1–3 days, and it is not common to have a severe reaction to the Tdap vaccine.

In rare cases, some people have an allergic reaction to Tdap. The most severe type is known as anaphylaxis.

Anaphylaxis: Symptoms and what to do

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

  • hives
  • swelling of the face or mouth
  • wheezing
  • fast, shallow breathing
  • a fast heart rate
  • clammy skin
  • anxiety or confusion
  • dizziness
  • vomiting
  • blue or white lips
  • fainting or loss of consciousness

If someone has these symptoms:

  1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
  2. Dial 911 or the number of the nearest emergency department.
  3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
  4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

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A 2017 review of 21 previous studies found no evidence that the Tdap vaccine poses any risk during pregnancy.

Another 2016 study of 403 newborns whose birthing parent received the Tdap vaccine during pregnancy also found no safety concerns for the parent or child.

The CDC recommends that most pregnant people have a Tdap shot early in the third trimester of every pregnancy, usually around 27–36 weeks. This is because it helps protect babies from the moment they are born.

Infants under 2 months are very vulnerable to severe pertussis because they have no immunity of their own. If it a newborn develops pertussis, it can be fatal. Getting the Tdap vaccine during pregnancy protects more than 3 out of 4 newborn babies from this disease.

People may have questions about the Tdap vaccine, and they can ask them for information, advice, and reassurance. Here are some prompts:

  • Have I had a DTaP vaccine?
  • When was my last Tdap vaccine?
  • When will I need to get my next Tdap shot?
  • Could I have an allergic reaction to this, based on my medical history?
  • Are there alternative options if I have previously had an allergic reaction to Tdap?
  • What is in the Tdap vaccine? Is it safe?
  • Does my health condition mean I cannot get a Tdap vaccine?
  • What should I do if I am anxious about the procedure?

The Tdap vaccine helps protect against tetanus, diphtheria, and pertussis. These can be life threatening illnesses. Getting the Tdap vaccine every 10 years helps protect people against these diseases.

The Tdap vaccine works by exposing the body to a small amount of inactivated proteins from each disease. Another vaccine, DTaP, protects against the same diseases in the same way. However, doctors use the DTaP vaccine for young children, whereas the Tdap vaccine is for adolescents and adults.

Most people over 7 should get a Tdap shot, including pregnant people. However, some people should not get it due to certain health conditions.