Diphtheria: Symptoms, Causes, Treatment & Vaccine Guide
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
TL;DR
Diphtheria is a rare but serious bacterial infection of the nose and throat caused by Corynebacterium diphtheriae. It typically starts with a sore throat, fever, and a thick gray membrane covering the tonsils within 2 to 5 days of infection. It is treated immediately with antibiotics and an antitoxin, usually in the hospital. The diphtheria vaccine (given as part of DTaP and Tdap) prevents it, but immunity fades, so booster shots are recommended every 10 years.
Quick Answer
What is diphtheria? A serious bacterial infection that usually affects the mucous membranes of the nose and throat, caused by the bacterium Corynebacterium diphtheriae.
How does it spread? Through airborne droplets from a cough or sneeze, and by touching contaminated items such as used tissues or hand towels.
What are the key symptoms? A thick gray membrane on the throat and tonsils, sore throat, hoarseness, swollen neck glands, fever, and trouble breathing, typically starting 2 to 5 days after infection.
How is it treated? Doctors treat it right away with antibiotics (such as penicillin or erythromycin) and an antitoxin that neutralizes the diphtheria toxin, often in the hospital with airway support.
How can you prevent it? The diphtheria-tetanus-pertussis vaccine protects against it. Children receive five shots starting at 2 months of age, and boosters are recommended at age 11 to 12 and then every 10 years.
What is diphtheria?
Diphtheria (dif-THEER-e-uh) is a serious bacterial infection that usually affects the mucous membranes of the nose and throat. It is extremely rare in the United States and other developed countries thanks to widespread vaccination. But many countries with limited health care or vaccination options still see high rates of the disease.
The infection can be treated with medications. However, in advanced stages it can damage the heart, kidneys, and nervous system. Even with treatment, diphtheria can be deadly, especially in children.
Diphtheria symptoms: what to watch for
Signs and symptoms usually begin 2 to 5 days after a person becomes infected. The list below summarizes what the infection typically looks like.
Gray throat membrane: A thick, gray membrane covering the throat and tonsils
Sore throat and hoarseness: Pain when swallowing and a rough or weak voice
Swollen neck glands: Enlarged lymph nodes visible or felt in the neck
Breathing difficulty: Trouble breathing or rapid breathing
Nasal discharge: Runny or blocked nose
Fever and chills: Elevated body temperature with shivering
Tiredness: Unusual fatigue and low energy
Some people infected with the bacteria develop only a mild illness or no obvious symptoms at all. These people are known as carriers. They are called carriers because they can spread the infection without being sick themselves, including to people who have not had the diphtheria vaccine.
A second form attacks the skin
A second type, called skin (cutaneous) diphtheria, affects the skin. It causes pain, redness, and swelling similar to other bacterial skin infections. Ulcers covered by a gray membrane can also be a sign of skin diphtheria.
This form is more common in tropical climates, but it also occurs in the United States. It tends to happen especially among people with poor hygiene who live in crowded conditions.
How diphtheria spreads
The infection is caused by the bacterium Corynebacterium diphtheriae, which usually multiplies on or near the surface of the throat or skin. It spreads in two main ways.
The first is through airborne droplets. When an infected person sneezes or coughs, a mist of contaminated droplets is released, and people nearby may inhale the bacteria. Diphtheria spreads easily this way, especially in crowded conditions.
The second route is through contaminated personal or household items. People sometimes catch diphtheria by handling an infected person's belongings, such as used tissues or hand towels that may carry the bacteria. Touching an infected wound can also transfer the bacteria.
Untreated people who have been infected can pass the bacteria to anyone who has not had the diphtheria vaccine, even if they show no symptoms.
Airborne droplets — How it happens: Coughing or sneezing releases contaminated mist that others inhale; Highest risk setting: Crowded conditions
Contaminated items — How it happens: Handling used tissues, hand towels, or other belongings of an infected person; Highest risk setting: Shared households
Infected wounds — How it happens: Direct contact with an infected skin wound (skin diphtheria); Highest risk setting: Poor hygiene, crowded living
Who is at risk?
The people at increased risk of catching diphtheria include children and adults who do not have up-to-date vaccinations, people living in crowded or unsanitary conditions, and anyone who travels to areas where diphtheria infections are more common.
The disease rarely occurs in the United States and Western Europe, where children have been vaccinated for decades. It is still common in developing countries where vaccination rates are low. In areas where vaccination is standard, diphtheria is mainly a threat to unvaccinated or inadequately vaccinated people who travel internationally or have contact with people from less developed countries.
When to see a doctor
Call your family doctor immediately if you or your child has been exposed to someone with diphtheria. If you are not sure whether your child has been vaccinated, schedule an appointment. Make sure your own vaccinations are current as well.
Possible complications
Left untreated, diphtheria can lead to several serious complications, because the bacteria produce a toxin that damages tissue beyond the infection site.
Breathing problems — What happens: The toxin damages tissue in the nose and throat, forming a tough gray membrane of dead cells and bacteria that can block the airway; Possible outcome: Obstructed breathing
Heart damage — What happens: The toxin spreads through the bloodstream and can inflame the heart muscle (myocarditis); Possible outcome: Slight to severe damage; at worst, heart failure and sudden death
Nerve damage — What happens: The toxin inflames nerves to the throat, arms, and legs; it can paralyze the muscles used for breathing; Possible outcome: Difficulty swallowing, muscle weakness, need for mechanical breathing support
With treatment, most people survive these complications, but recovery is often slow. Diphtheria is fatal about 5% to 10% of the time. Death rates are higher in children under age 5 and adults older than age 40.
How diphtheria is diagnosed
Doctors may suspect diphtheria in a sick child who has a sore throat with a gray membrane covering the tonsils and throat. The diagnosis is confirmed when the bacteria grow in a lab culture of material taken from the throat membrane.
For skin diphtheria, doctors can take a tissue sample from an infected wound and have it tested in a lab. Importantly, if a doctor suspects diphtheria, treatment begins immediately, even before the results of the bacterial tests are available.
Diphtheria treatment: what to expect
Diphtheria is treated as a serious illness, immediately and aggressively. Doctors first make sure the airway is not blocked or reduced. In some cases, they may place a breathing tube in the throat to keep the airway open until the inflammation goes down.
Antibiotics such as penicillin or erythromycin help kill the bacteria in the body and clear up the infection. They also shorten the time that someone with diphtheria is contagious.
An antitoxin counteracts the diphtheria toxin in the body. Before giving it, doctors may perform skin allergy tests to make sure the patient is not allergic to the antitoxin. If an allergy is found, the doctor will likely recommend not receiving it.
Children and adults with diphtheria often need to be in the hospital. They may be isolated in an intensive care unit because the disease can spread easily to anyone not vaccinated against it.
Treatment for people who were exposed
If you have been exposed to someone infected with diphtheria, see a doctor for testing and possible treatment. The doctor may prescribe antibiotics to help prevent the disease from developing. You may also need a booster dose of the diphtheria vaccine. People found to be carriers of diphtheria are treated with antibiotics to clear the bacteria from their systems as well.
Recovery and self-care
Recovering from diphtheria requires a lot of bed rest. Avoiding physical exertion is particularly important if the 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 are contagious helps prevent the spread of the infection. Careful hand-washing by everyone in your home is important for limiting it.
One point many people find surprising: having diphtheria does not guarantee lifetime immunity. Unlike some other infections, you can get diphtheria more than once if you are not fully vaccinated. Once you recover, you will need a full course of the diphtheria vaccine to prevent a recurrence.
Prevention: the diphtheria vaccine
Before antibiotics existed, diphtheria was a common illness in young children. Today, it 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 shot is known as the diphtheria-tetanus-pertussis vaccine. The latest version is called the DTaP vaccine for children and the Tdap vaccine for adolescents and adults.
In the United States, doctors recommend this vaccine during infancy as one of the standard childhood vaccinations. The series consists of five shots, typically given in the arm or thigh at 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years of age.
Side effects and who may not be able to receive it
The vaccine is effective at preventing diphtheria, but some side effects can occur. Some children may have a mild fever, fussiness, drowsiness, or tenderness at the injection site after a DTaP shot. Ask your doctor what you can do to minimize or relieve these effects.
Serious complications are very rare. In rare cases, the DTaP vaccine causes serious but treatable complications, such as an allergic reaction where hives or a rash develop 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.
Why booster shots matter
After the childhood series, you need booster shots to maintain your immunity, because protection against diphtheria fades with time. Children who received all recommended vaccinations before age 7 should get their first booster at around age 11 or 12. The next booster is recommended 10 years later, then repeated at 10-year intervals.
Boosters are particularly important if you travel to an area where diphtheria is common. The booster is given as a Tdap vaccine or as a tetanus-diphtheria (Td) combination, injected into the arm or thigh. Tdap is also recommended once during pregnancy, regardless of previous vaccinations.
DTaP — Given to: Children; Key timing: Five shots at 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years
Tdap — Given to: Adolescents and adults; Key timing: First booster around age 11 to 12; once during pregnancy
Td — Given to: Booster for diphtheria and tetanus; Key timing: Every 10 years after the initial series
Talk to your doctor about vaccines and booster shots if you are 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 are not up to date with the vaccine schedule.
Preparing for a doctor's appointment
If you have symptoms of diphtheria or have been in contact with someone who has it, call your doctor right away. Depending on your symptoms and vaccination history, you may be told to go to the emergency room or to call 911 or your local emergency number.
Before the visit, gather your symptom history, vaccination record, and a list of current medications. Your doctor will want to know about recent travel abroad, any exposure to diphtheria cases, and whether close contacts have similar symptoms.
Useful questions to ask include what is causing your symptoms, what tests you need, what treatments are available, and whether there are long-term complications. Your doctor will likely ask when your symptoms started, whether you have had trouble breathing or swallowing, and whether all your vaccinations are current.
Bottom line
Diphtheria remains a rare disease in vaccinated countries, but it has not disappeared. The bacteria still circulate in parts of the world with low vaccination rates, and the risk mainly reaches unvaccinated or under-vaccinated people through travel or contact with travelers.
The good news is that the disease is both treatable and preventable. Doctors act fast: if diphtheria is suspected, antibiotics and an antitoxin begin right away, even before lab results confirm the diagnosis. Most patients who receive treatment survive, although recovery from complications can take time.
The vaccine is the strongest protection available. A five-shot childhood series plus boosters every 10 years keeps immunity current. If you are unsure of your vaccination status, or planning to travel to a region where diphtheria is common, talk to your doctor about getting up to date.
Check your family's vaccination records today. If it has been more than 10 years since your last diphtheria-tetanus-pertussis booster, or if you are traveling abroad soon, call your doctor or pharmacist to schedule a booster shot.
FAQ
What are the first signs of diphtheria?
Diphtheria usually begins 2 to 5 days after infection with a sore throat, fever, chills, and tiredness. The most distinctive sign is a thick, gray membrane covering the throat and tonsils, often with swollen glands in the neck.
Is diphtheria contagious, and how does it spread?
Yes. It spreads easily through airborne droplets when an infected person coughs or sneezes, and by touching contaminated items like used tissues or hand towels. People without symptoms can still spread it if they have not been treated.
Can diphtheria be cured?
Yes, diphtheria is treatable. Doctors use antibiotics to kill the bacteria and an antitoxin to neutralize the toxin, usually in a hospital setting. Most treated patients survive, though recovery from complications such as heart or nerve damage can be slow.
Is diphtheria still around today?
Diphtheria is extremely rare in the United States and Western Europe thanks to decades of vaccination, but it is still common in developing countries with low vaccination rates. In vaccinated regions, the main risk is for unvaccinated people who travel internationally.
Do I need a diphtheria booster as an adult?
Yes. Immunity to diphtheria fades over time, so boosters are recommended about 10 years after the initial series and repeated every 10 years. Boosters are especially important before traveling to areas where diphtheria is common, and one Tdap dose is recommended during pregnancy.
References
Health information, not medical advice. This article is for general education and is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider about your own health, and seek emergency care for urgent symptoms.
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