What Is Diphtheria? Everything You Need to Know

What Is Diphtheria?

Diphtheria is a highly contagious bacterial infection that affects the throat and upper airways—and sometimes the skin. Though it's rare in countries with strong vaccination programs, it can still occur and cause serious complications, especially in places where vaccination coverage is low.

It’s caused by a bacterium called Corynebacterium diphtheriae, which produces a dangerous toxin that can damage tissues in the body. This isn’t just a sore throat—it’s potentially life-threatening.

How Does Diphtheria Spread?

Diphtheria spreads from person to person through respiratory droplets—think coughing, sneezing, or even talking up close. You can also get infected by:

• Touching objects contaminated with the bacteria (like toys or towels)

• Close contact with skin sores of an infected person

• Sharing personal items like drinking glasses or utensils

And here's the tricky part: people can carry and spread diphtheria even if they don’t show symptoms.

Symptoms of Diphtheria

Diphtheria usually starts out like a regular sore throat, but it can quickly turn dangerous. Watch out for:

• A thick gray or white coating in the throat or nose

• Sore throat, difficulty swallowing, and hoarseness

• Swollen glands in the neck (a "bull neck" appearance)

• Fever, chills, and feeling tired or weak

• Fast or irregular heartbeat

• Shortness of breath if the airway is blocked

In some cases, diphtheria affects the skin, causing painful ulcers or sores. These cutaneous forms of diphtheria are more commonly seen in tropical or subtropical climates.

Complications: Why Diphtheria Is So Dangerous

The diphtheria toxin doesn’t just stay in the throat—it can spread through the bloodstream and damage organs like:

• The heart (causing myocarditis, which can lead to heart failure)

• The nerves (leading to paralysis)

• The kidneys

• In severe cases, diphtheria can cause death, especially if left untreated 

Children under 5 and adults over 60 are at the highest risk of severe complications.

Who’s Most at Risk?

You’re most at risk if:

• You haven’t been vaccinated or missed booster shots

• You live or travel to areas with low vaccination rates

• You have weakened immunity

• You’re exposed to someone with diphtheria or a carrier 

Outbreaks are still reported in parts of Asia, Africa, and Eastern Europe.

Diagnosis and Testing

If diphtheria is suspected, doctors may:

• Take a swab from your throat or wound to test for the bacteria

• Order blood tests to check for signs of infection or organ damage

• Monitor breathing and heart function 

Because diphtheria can progress quickly, doctors usually start treatment immediately, even before lab confirmation.

How Diphtheria Is Treated

Early treatment is crucial. Doctors use:

• Antitoxin injections to neutralize the diphtheria toxin

• Antibiotics (like penicillin or erythromycin) to kill the bacteria

• Isolation to prevent spreading the infection to others

• Supportive care (like IV fluids, oxygen, or breathing assistance if needed)

Hospitalization is usually required, especially for severe cases. Even with treatment, complications can happen, so prevention through vaccination is key.

Prevention: The Vaccine Works

Diphtheria is vaccine-preventable, and that’s great news.

For children:

• The DTaP vaccine protects against diphtheria, tetanus, and pertussis (whooping cough)

• It’s given in a series of doses starting at 2 months of age

For teens and adults:

• A Tdap booster is recommended around age 11–12

• Adults should get a Td booster every 10 years

Note: Vaccination schedules may vary slightly depending on your country’s national immunization program. Always check with your local health authority or doctor to stay on track.

Vaccination is your best defense—even if you’ve had diphtheria before, you’ll still need the vaccine to protect against future infections.

Travel Advice

If you're traveling to a country where diphtheria is still common, check your vaccination status well ahead of time. The CDC and WHO recommend being fully vaccinated before traveling.

Sources:

Centers for Disease Control and Prevention (CDC)
https://www.cdc.gov/diphtheria/index.html

World Health Organization (WHO)
https://www.who.int/news-room/fact-sheets/detail/diphtheria

National Health Service (NHS), UK
https://www.nhs.uk/conditions/diphtheria/

Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/diphtheria/symptoms-causes/syc-20351734

Johns Hopkins Medicine
https://www.hopkinsmedicine.org/health/conditions-and-diseases/diphtheria