What Is Diphtheria? Everything You Need to Know
Learn about diphtheria—what it is, how it spreads, symptoms to watch for, complications, treatment, and vaccine prevention—in this complete, easy-to-understand guide.
DISEASES AND CONDITIONS
Dr. S. Ali
6/8/20253 min read


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