Health conditions


  • Diphtheria is a serious disease caused by a toxin (poison) made by bacteria.
  • It causes a thick grey coating in the back of the nose or throat that makes it hard to breathe or swallow.
  • It can be deadly. The dTpa vaccine protects all age groups against diphtheria.

Diphtheria is rarely seen in Australia owing to good hygiene standards and most people being vaccinated against the disease.

Diphtheria is a serious disease – 5 to 10 per cent of all persons with diphtheria die.

Up to 20 per cent of cases lead to death in certain age groups of individuals, in particular children under 5 and adults over 40.

How is diphtheria spread?

The diphtheria bacteria live in the mouth, throat, and nose of an infected person and can be passed to others by coughing or sneezing.

Occasionally, transmission occurs from skin sores or through articles soiled with discharge from sores of infected persons.

What are the signs and symptoms of diphtheria?

The symptoms generally appear 2 to 5 days after exposure, with a range of 1 to 10 days.

Diphtheria starts like a cold, followed by:

  • mild fever
  • chills
  • sore throat, which progresses to difficulty in swallowing.

The coating on the throat can get so thick that it blocks the airway, so the person can’t breathe.


Most complications of diphtheria are due to the release of the toxin, or poison.

The most common complications are inflammation of the:

  • heart, leading to abnormal heart rhythms
  • nerves, which may cause temporary paralysis of some muscles.

If the paralysis affects the diaphragm (the major muscle for breathing), the person may develop pneumonia or respiratory failure.

The thick membrane coating at the back of the throat may cause serious breathing problems, even suffocation.

How do I know if I have diphtheria?

Clinical systemic diphtheria is usually caused by a toxigenic strain of diphtheria – it is a medical emergency.

If you have a severe sore throat along with fever and difficulty breathing, see your doctor immediately.

The diagnosis of diphtheria can only be confirmed after your doctor takes a small sample of the infected material from your:

  • throat
  • other site, such as the skin.

The sample is tested in a laboratory.

If symptoms are severe, and you have recently travelled overseas, contact your local emergency department to seek advice and direction.

How is diphtheria treated?

If there is a suspicion that you have diphtheria your doctor will start you on medication immediately as the disease progresses very quickly.

Antibiotics are used, and an antitoxin injection is given.

While you have diphtheria

You should stay isolated – away from other people – until 2 days after you have started taking antibiotics.

You should not sit among other people in a waiting room.

How can diphtheria be prevented?

Ensure that your vaccinations are up to date.

Adopt good personal hygiene to help protect your health when at:

  • home
  • work
  • school
  • overseas.

You can reduce the risk of getting diphtheria by following this advice:

  • cover your nose and mouth with a tissue when you cough or sneeze
  • throw tissues in the bin after you use them
  • wash your hands often with soap and water, especially after you cough or sneeze. Alcohol based hand cleaners are also effective
  • wash your hands before preparing food
  • avoid touching your eyes, nose or mouth, as germs are spread this way
  • avoid close contact with people who have colds
  • wash your child’s toys frequently to remove traces of the any viruses
  • if you have a cold, stay home from work or school and limit contact with other people to keep from infecting them
  • if you child develops a cold, keep them home for the first few days to stop them infecting others

Notifiable disease

Diphtheria is a notifiable disease so doctors, hospitals and laboratories must inform the Department of Health of you or your child’s diagnosis. Notification is confidential.

Department of Health staff will talk to you or your doctor to find out how the infection occurred, identify other people at risk of infection, and let you know about immunisation and whether you or your child needs to stay away from work, school or group gatherings.

Where to get help

Last reviewed: 23-10-2023

Public Health

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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