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Medically reviewed by Last updated on Jan 26, 2024.


Diphtheria (dif-THEER-e-uh) is a serious bacterial infection that usually affects the mucous membranes of the nose and throat. Diphtheria is extremely rare in the United States and other developed countries thanks to widespread vaccination against the disease. However, many countries with limited health care or vaccination options still experience high rates of diphtheria.

Diphtheria can be treated with medications. But in advanced stages, diphtheria can damage the heart, kidneys and nervous system. Even with treatment, diphtheria can be deadly, especially in children.


One sign of diphtheria is swollen glands (enlarged lymph nodes) in the neck.


Diphtheria signs and symptoms usually begin 2 to 5 days after a person becomes infected. Signs and symptoms may include:

In some people, infection with diphtheria-causing bacteria causes only a mild illness — or no obvious signs and symptoms at all. Infected people who stay unaware of their illness are known as carriers of diphtheria. They're called carriers because they can spread the infection without being sick themselves.

Skin (cutaneous) diphtheria

A second type of diphtheria can affect the skin, causing pain, redness and swelling similar to other bacterial skin infections. Ulcers covered by a gray membrane also may be a sign of skin diphtheria.

Although it's more common in tropical climates, diphtheria on the skin also occurs in the United States. It may happen especially among people with poor hygiene who live in crowded conditions.

When to see a doctor

Call your family doctor immediately if you or your child has been exposed to someone with diphtheria. If you're not sure whether your child has been vaccinated against diphtheria, schedule an appointment. Make sure your own vaccinations are current.


Diphtheria is caused by the bacterium Corynebacterium diphtheriae. The bacterium usually multiplies on or near the surface of the throat or skin. C. diphtheriae spreads through:

People who have been infected by the diphtheria bacteria and who haven't been treated can infect people who haven't had the diphtheria vaccine — even if they don't show any symptoms.

Risk factors

People who are at increased risk of catching diphtheria include:

Diphtheria rarely occurs in the United States and Western Europe, where children have been vaccinated against the condition for decades. However, diphtheria is still common in developing countries where vaccination rates are low.

In areas where diphtheria vaccination is standard, the disease is mainly a threat to unvaccinated or inadequately vaccinated people who travel internationally or have contact with people from less developed countries.


Left untreated, diphtheria can lead to:

With treatment, most people with diphtheria survive these complications, but recovery is often slow. Diphtheria is fatal about 5% to 10% of the time. Rates of death are higher in children under age 5 or adults older than age 40.


Before antibiotics were available, diphtheria was a common illness in young children. Today, the disease is not only treatable but also preventable with a vaccine.

The diphtheria vaccine is usually combined with vaccines for tetanus and whooping cough (pertussis). The three-in-one vaccine is known as the diphtheria, tetanus and pertussis vaccine. The latest version of this vaccine is known as the DTaP vaccine for children and the Tdap vaccine for adolescents and adults.

The diphtheria, tetanus and pertussis vaccine is one of the childhood vaccinations that doctors in the United States recommend during infancy. Vaccination consists of a series of five shots, typically administered in the arm or thigh, given to children at these ages:

The diphtheria vaccine is effective at preventing diphtheria. But there may be some side effects. Some children may experience a mild fever, fussiness, drowsiness or tenderness at the injection site after a DTaP shot. Ask your doctor what you can do for your child to minimize or relieve these effects.

Complications are very rare. In rare cases, the DTaP vaccine causes serious but treatable complications in a child, such as an allergic reaction (hives or a rash develops within minutes of the injection).

Some children — such as those with epilepsy or another nervous system condition — may not be able to get the DTaP vaccine.

Booster shots

After the initial series of vaccinations in childhood, you need booster shots of the diphtheria vaccine to help you maintain your immunity. That's because immunity to diphtheria fades with time.

Children who received all of the recommended vaccinations before age 7 should receive their first booster shot at around age 11 or 12. The next booster shot is recommended 10 years later, then repeated at 10-year intervals. Booster shots are particularly important if you travel to an area where diphtheria is common.

The booster is given as a Tdap vaccine or as a diphtheria booster combined with the tetanus booster — the tetanus-diphtheria (Td) vaccine. This combination vaccine is given by injection, usually into the arm or thigh.

The vaccine for Tdap is an alternative vaccine for adolescents ages 11 through 18 and adults who haven't previously had a booster. It's also recommended once during pregnancy, regardless of previous vaccinations.

Talk to your doctor about vaccines and booster shots if you're unsure of your vaccination status. A Tdap vaccine may also be recommended as part of the Td series for children ages 7 through 10 who aren't up to date with the vaccine schedule.


Doctors may suspect diphtheria in a sick child who has a sore throat with a gray membrane covering the tonsils and throat. Growth of C. diphtheriae in a lab culture of material from the throat membrane confirms the diagnosis. Doctors can also take a tissue sample from an infected wound and have it tested in a lab to check for the type of diphtheria that affects the skin (cutaneous diphtheria).

If a doctor suspects diphtheria, treatment begins immediately, even before the results of bacterial tests are available.


Diphtheria is a serious illness. Doctors treat it immediately and aggressively. Doctors first ensure that the airway isn't blocked or reduced. In some cases, they may need to place a breathing tube in the throat to keep the airway open until the airway is less inflamed. Treatments include:

Children and adults who have diphtheria often need to be in the hospital for treatment. They may be isolated in an intensive care unit because diphtheria can spread easily to anyone not vaccinated against the disease.

Preventive treatments

If you've been exposed to a person infected with diphtheria, see a doctor for testing and possible treatment. Your doctor may give you a prescription for antibiotics to help prevent you from developing the disease. You may also need a booster dose of the diphtheria vaccine.

People found to be carriers of diphtheria are treated with antibiotics to clear their systems of the bacteria as well.

Self care

Recovering from diphtheria requires lots of bed rest. Avoiding any physical exertion is particularly important if your heart has been affected. You may need to get your nutrition through liquids and soft foods for a while because of pain and difficulty swallowing.

Strict isolation while you're contagious helps prevent the spread of the infection. Careful hand-washing by everyone in your home is important for limiting the spread of the infection.

Once you recover from diphtheria, you'll need a full course of diphtheria vaccine to prevent a recurrence. Unlike some other infections, having diphtheria doesn't guarantee lifetime immunity. You can get diphtheria more than once if you're not fully vaccinated against it.

Preparing for your appointment

If you have symptoms of diphtheria or have come into contact with someone who has diphtheria, call your doctor right away. Depending on the severity of your symptoms and on your vaccination history, you may be told to go to the emergency room or call 911 or your local emergency number for medical help.

If your doctor determines that he or she should see you first, try to be well prepared for your appointment. Here's some information to help you get ready and know what to expect from your doctor.

Information to gather in advance

The list below suggests questions to ask your doctor about diphtheria. Don't hesitate to ask more questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, too, such as:

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