Understanding the Reasons: Why Not to Get the Tdap Vaccine?

October 12, 2025 •

3 min read

While the Tdap vaccine is highly effective, preventing an estimated 84% of pertussis cases shortly after vaccination, there are specific medical reasons why a person might delay or forego the shot. Understanding these valid concerns is crucial, so this article explores why not to get the Tdap vaccine in certain situations.

Quick Summary

This article details the specific medical contraindications and precautions for the Tdap vaccine. It covers severe allergies, neurological history, and other health conditions that may be reasons to avoid or postpone vaccination.

Key Points

Absolute Contraindications: A history of a life-threatening allergic reaction (anaphylaxis) or encephalopathy within 7 days of a previous dose are primary reasons not to get the Tdap vaccine.
Neurological Precautions: A history of Guillain-Barré Syndrome (GBS) within six weeks of a prior tetanus vaccine is a precaution, requiring a doctor's consultation.
Severe Reaction History: Those who have experienced a severe Arthus-type reaction to a previous tetanus or diphtheria vaccine should also consult a provider before another dose.
Acute Illness: People with moderate to severe acute illnesses are typically advised to postpone vaccination until they have recovered.
Risk vs. Benefit: For most people, the benefit of protection from tetanus, diphtheria, and pertussis significantly outweighs the very small risks associated with the vaccine.
Pregnancy Recommendation: The Tdap vaccine is recommended during each pregnancy, optimally between 27 and 36 weeks, to protect the newborn from pertussis.
Common Side Effects: Most side effects are mild and temporary, such as soreness at the injection site, headache, and fatigue.

Understanding the Tdap Vaccine

The Tdap vaccine is a combination booster shot that protects against three serious bacterial diseases: tetanus, diphtheria, and pertussis (whooping cough).

Tetanus (Lockjaw): Caused by bacteria found in soil and dust, tetanus enters the body through wounds. It produces a toxin that leads to painful muscle stiffness, spasms, and can be fatal in up to 1 in 5 cases.
Diphtheria: This highly contagious infection can cause a thick coating to form in the back of the throat, leading to breathing difficulties, heart failure, paralysis, or death.
Pertussis (Whooping Cough): A very contagious respiratory illness that causes uncontrollable, violent coughing fits. It is especially dangerous for infants, potentially causing pneumonia, brain damage, or death.

Healthcare providers recommend Tdap for adolescents, typically at age 11 or 12, and a booster every 10 years for adults. It is also recommended during each pregnancy to protect the newborn.

Absolute Contraindications: Who Should NOT Get the Tdap Vaccine?

A contraindication is a specific situation where a medical treatment should not be used because it could be harmful. For the Tdap vaccine, there are two primary reasons not to vaccinate:

1. Severe Allergic Reaction (Anaphylaxis)

A history of a life-threatening allergic reaction to a previous dose of any vaccine containing tetanus, diphtheria, or pertussis, or to any vaccine component, is a contraindication for the Tdap vaccine. Symptoms of anaphylaxis include hives, swelling, difficulty breathing, fast heartbeat, dizziness, or weakness.

2. Encephalopathy Following a Previous Dose

Experiencing encephalopathy (a brain disorder) within 7 days of a prior pertussis-containing vaccine dose, if not due to another cause, is a reason to avoid the pertussis component of Tdap. A Td vaccine may be an alternative. This reaction is very rare.

Precautions: Who Should Discuss the Tdap Vaccine with a Doctor?

A precaution is a condition that might increase the risk of an adverse reaction or affect the vaccine's effectiveness. In these situations, a healthcare provider should be consulted.

1. History of Guillain-Barré Syndrome (GBS)

If a person developed GBS, a rare nerve disorder, within 6 weeks of a previous tetanus toxoid-containing vaccine, this is a precaution. Any link between tetanus vaccines and GBS is considered extremely rare.

2. History of Arthus-type Hypersensitivity Reaction

A severe local reaction (Arthus reaction) involving significant pain and swelling after a prior tetanus or diphtheria toxoid-containing vaccine is a precaution. Vaccination may be deferred for at least 10 years.

3. Progressive or Unstable Neurologic Disorder

Having a progressive or unstable neurologic condition, such as uncontrolled seizures, is a precaution for the pertussis component of Tdap. Vaccination should typically be deferred until the condition is stable.

4. Moderate or Severe Acute Illness

Individuals with moderate or severe illness should generally postpone Tdap vaccination until they recover. Minor illnesses like a cold are usually not a reason to delay.

Vaccine Risks vs. Disease Risks

The risks from tetanus, diphtheria, and pertussis are generally more severe than the risks associated with the Tdap vaccine.


Feature	Risk from Tdap Vaccine	Risk from Diseases (Tetanus, Diphtheria, Pertussis)
Common Effects	Pain, redness, or swelling at injection site; mild fever; headache; fatigue.	Tetanus: Painful muscle spasms. Diphtheria: Sore throat, thick coating. Pertussis: Severe coughing fits.
Severe Effects	Extremely rare; may include severe allergic reaction (anaphylaxis).	Tetanus: Lockjaw, breathing trouble, death (1 in 5 cases). Diphtheria: Heart failure, paralysis, death. Pertussis: Pneumonia, convulsions, brain damage, death (especially in infants).
Neurological	Very rare; precaution for those with a history of GBS within 6 weeks of a prior dose.	Tetanus: Affects the nervous system. Diphtheria: Can cause paralysis. Pertussis: Can cause seizures and brain damage.

Conclusion

Making informed health decisions about vaccines requires accurate information and medical guidance. While the Tdap vaccine is safe and effective for most individuals, specific medical reasons do exist for not receiving it. These include a history of severe allergic reaction or certain neurological events after a previous dose. Other conditions, like a history of GBS or a severe Arthus reaction, necessitate discussion with a healthcare provider to assess individual risks and benefits. For the majority, the protection offered by the Tdap vaccine against potentially fatal diseases outweighs its minimal risks.

Authoritative Resource: For comprehensive information, consult the Centers for Disease Control and Prevention (CDC) page on the Tdap vaccine.

Frequently Asked Questions

Individuals who have had a severe, life-threatening allergic reaction (anaphylaxis) to a previous dose of a tetanus, diphtheria, or pertussis vaccine, or who developed encephalopathy within 7 days of a prior dose, should not get the Tdap vaccine.

The most common side effects are typically mild and go away on their own. They include pain, redness, or swelling where the shot was given, mild fever, headache, fatigue, and sometimes nausea, vomiting, or diarrhea.

Yes, people with minor illnesses, such as a cold, can usually be vaccinated. However, if you are moderately or severely ill, you should wait until you recover.

Yes, the Tdap vaccine is recommended as safe and effective during each pregnancy, preferably between 27 and 36 weeks gestation. This passes protective antibodies to the baby, offering protection against whooping cough in early life.

GBS is a rare autoimmune disorder. Having a history of GBS within 6 weeks of a previous tetanus-containing vaccine is a precaution, not a contraindication. A healthcare provider should be consulted to weigh the risks and benefits before vaccination.

An Arthus reaction is a severe local reaction at the injection site, involving pain and swelling. A history of this type of reaction after a previous tetanus or diphtheria-containing vaccine is a precaution for future doses.

If you have a contraindication to the pertussis component (e.g., prior encephalopathy), you may be able to receive the Td vaccine, which protects against only tetanus and diphtheria.