Pronounced: Dif-THEER-e-uh


Diphtheria is a life-threatening bacterial infection that requires immediate care.


Certain bacteria cause diphtheria. The infection spreads between people through contact. This can happen by:

  • Inhaling the bacteria after a person coughs or sneezes
  • Using personal items such as tissues or drinking glasses
  • Having contact with their skin

Risk Factors

Your risk is higher if you:

  • Haven’t had the diphtheria vaccine
  • Haven't had a booster dose in the past 10 years
  • Have problems with immunity


People without symptoms can spread diphtheria to others. Symptoms usually appear within 2-5 days after infection.

The clearest sign of infection is a gray covering on the back of your throat. This covering can come off and block your airway.

Other common symptoms:

  • Sore throat
  • Painful swallowing
  • High fever (up to 103°F)
  • Cough—may have a barking sound
  • Swollen lymph glands in the neck
  • Breathing problems
  • Swallowing problems
  • Weakness
  • Skin infection

Left untreated, the bacteria can produce a poison that spreads throughout your body. This may cause heart, nerve, and kidney damage.

Swollen Glands in the Neck

Swollen lymph node
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Your doctor will ask about your symptoms and health history. Your doctor may suspect diphtheria based on your symptoms and a physical exam. A test swab from your throat can confirm it.


Diphtheria is a medical emergency. Care will start right away, even if your test results aren’t ready.

Care involves:

  • An antitoxin
  • Antibiotics
  • Isolation and bed rest


A vaccine will prevent the disease. Almost all children should get the series. It will also protect against tetanus and pertussis. If your child missed their vaccines, there are catch-up schedules. Talk to your child’s doctor for specifics.


Centers for Disease Control and Prevention
National Institute of Allergy and Infectious Diseases


Caring for Kids—Canadian Paediatric Society
Public Health Agency of Canada


Diphtheria. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/pubs/pinkbook/dip.html. Updated November 9, 2015. Accessed May 14, 2018.
Diphtheria. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T114762/Diphtheria . Updated January 4, 2018. Accessed May 14, 2018.
Immunization schedules. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/schedules/index.html. Updated February 6, 2018. Accessed May 22, 2017.
Td (tetanus, diphtheria) VIS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/td.html. Updated April 11, 2017. Accessed May 14, 2018.
Tdap (tetanus, diphtheria, pertussis) VIS. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/tdap.html. Updated October 18, 2016. Accessed May 14, 2018.
Last reviewed May 2018 by David L. Horn, MD, FACP
Last Updated: 5/14/2018

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