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Diphtheria is a serious and life-threatening infectious disease that can be prevented with vaccination. It is very infectious and can be passed on easily between people, and usually affects the upper respiratory tract (nose and throat), but occasionally the skin. 

Before a vaccine was introduced in 1940, diphtheria was a common childhood illness which killed an average of 3,500 children a year in the UK. Cases are no longer seen as frequently in countries like the UK any more because of vaccination, but the disease is still common in some parts of the world. 

Diphtheria causes death in up to 1 in 10 of those who get it, even with treatment.

Travelers to areas with a larger amount of cases can bring diphtheria back to the UK, which may put unvaccinated people at risk.

See the impact of the diphtheria vaccine, sourced from the green book, below:

diphtheria cases 1914 2003

Click here for an accessible text version of this graph. 

Diphtheria usually affects the nose and throat, but sometimes it can affect the skin.

Early symptoms of diphtheria include a temperature (fever), feeling sick, a headache, sore throat and raised heart rate. Once cells start to die in the throat, they build up to form a membrane that looks like a thick grey-white coating at the back of the throat. This can cause breathing difficulties and eventually choking.

The form of diphtheria which affects the skin can cause ulcers.

People can carry diphtheria and pass it on to others without showing any symptoms themselves.


Diphtheria is spread by water droplets that are coughed or sneezed into the air by an infected person, or by contact with someone who has the disease. It can also be caught from items such as clothes, bedding or toys that have been in contact with someone who has diphtheria.

People who have diphtheria are infectious for up to 4 weeks or sometimes even longer.


It is not possible to develop natural immunity to diphtheria without getting the disease itself, which involves a high risk of death. The recommended way to protect your child is through vaccination.

In the UK, babies and children receive five doses of vaccine to protect them from diphtheria:

The repeated doses are needed to give a good immune response.

Adults who are travelling to countries where diphtheria is more common may be advised to have a booster vaccine. The vaccine offered is usually the same as the Teenage Booster vaccine.

Antibiotics are available to kill the diphtheria bacteria, as well as medicines that stop the effects of the harmful toxins produced by the bacteria.  Treatment usually lasts a few weeks. 


Diphtheria is dangerous because the bacteria which cause it produce a powerful toxin (poison). The toxin kills cells in the mouth, nose and throat. The dead cells quickly build up and form a membrane which can attach to the throat and lead to death by choking. Diphtheria can also affect the heart (causing heart failure and death) and the nerves (causing neurological damage including weakness and numbness of limbs).

Three species of diphtheria bacteria produce toxins that are able to cause severe disease.

  1. Corynebacterium diphtheriae is the most infectious of these bacteria, and also the most common globally.
  2. Corynebacterium ulcerans is less common; it can cause classic diphtheria symptoms as well as a form of diphtheria that affects the skin and causes ulcers. This form of diphtheria usually occurs in countries where it is difficult to practise good hygiene.
  3. Corynebacterium pseudotuberculosis is also less common.

The last two species are often associated with farm animal contact and raw dairy products. Some strains of diphtheria bacteria do not produce toxins and cause only mild disease, such as a sore throat.

The graph below shows that before vaccination was introduced in the UK in 1942, there were on average 55,000 cases of diphtheria leading to around 3,500 deaths each year (mostly children). The vaccine has been so effective, diphtheria has caused only four deaths in the UK in the last twenty years. All of these people were unvaccinated. Most cases of diphtheria that have occurred in recent years in the UK have been brought in from the Indian subcontinent or from Africa.

The number of diphtheria cases in the UK is very low at the moment (10-20 confirmed cases a year over the last 20 years). However, because diphtheria is so infectious, there is a risk that an outbreak could occur if vaccination levels fall. An example of this was shown in the countries of the former Soviet Union in the early 1990s. The Soviet Union had a well-established programme of childhood vaccination. However, after it broke up into separate countries, childhood vaccination levels fell, and this led to a diphtheria epidemic.

Between 1990 and 1998 there were 157,000 cases of diphtheria and 5,000 deaths. The outbreak was eventually brought under control by a massive vaccination programme. See Diphtheria in the Former Soviet Union: Reemergence of a Pandemic Disease for more information.


diphtheria 1914 2013

Click here for an accessible text version of this graph

Source: Public Health England


Page last updated Tuesday, January 02, 2024