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Overview

What Is Diphtheria?

Diphtheria is a serious bacterial infection caused by toxin-producing Corynebacterium diphtheriae. The toxin can damage the throat, airways, heart, nerves, and other organs. Respiratory diphtheria affects the nose, throat, or airways, while cutaneous diphtheria affects the skin. Anyone can be affected, but unvaccinated people and those living in or traveling to areas with ongoing transmission have greater risk.

RESPIRATORY FORM

Infection affecting the nose, throat, or airways. It may cause a thick coating in the throat and can interfere with breathing.

SKIN FORM

Infection affecting the skin, often around an existing wound or break in the skin. Its symptoms and severity may differ from respiratory disease.

Symptoms

Diphtheria Symptoms

Diphtheria symptoms may begin several days after exposure. Respiratory disease can worsen quickly, especially when swelling or a membrane narrows the airway. Symptoms such as difficulty breathing, inability to swallow, or rapidly increasing neck swelling require emergency care rather than watchful waiting.

  • Sore throat
  • Fever
  • Swollen neck
  • Weakness
  • Difficulty swallowing
  • Difficulty breathing
  • Thick gray or white coating in the throat (pseudomembrane)
  • Painful skin sores
  • Open skin ulcers
  • Gray coating over a sore
  • Redness around a sore

How It Spreads

How Diphtheria Spreads

Respiratory diphtheria can spread through droplets released during coughing or sneezing and through close contact with an infected person. Cutaneous diphtheria can spread through contact with infected skin sores or items contaminated with wound secretions. People may be more likely to encounter the infection in crowded settings or in areas with ongoing transmission.

  • Diphtheria can spread through respiratory droplets during close contact.
  • Contact with infected skin sores can spread cutaneous diphtheria.
  • Shared items contaminated with respiratory or wound secretions may contribute to spread.
  • Crowded living conditions can increase exposure opportunities.
  • Travel to areas with ongoing transmission can increase exposure risk.

Reduce spread

Act promptly after exposure

After close contact with someone who may have diphtheria, contact a healthcare professional and follow public-health instructions. Close contacts may need evaluation, preventive antibiotics, testing, or a vaccination review; avoid close contact with others while infectious or while awaiting guidance.

Risk Factors

Risk Factors for Diphtheria

Risk categoryExamples
Addressable risksBeing unvaccinated or behind on boosters, close contact with an infected person, and delayed evaluation after exposure.
Situational risksTravel or residence in an area with ongoing transmission, crowded living conditions, and limited access to healthcare.
Health and age considerationsYoung children, older adults, and people with weakened immune systems may be more vulnerable to severe infection.

Complications

Diphtheria Complications

Complications are more likely when treatment is delayed. They may result from the toxin damaging organs or from swelling and a membrane blocking the airway. Prompt medical care can help clinicians manage the infection and monitor for these problems.

  • Blocked airway
  • Heart inflammation (myocarditis)
  • Abnormal heart rhythms
  • Nerve damage (neuropathy)
  • Kidney injury
  • Death

Diagnosis

How Diphtheria Is Diagnosed

Clinicians consider symptoms, examination findings, vaccination history, travel, and possible exposure when evaluating diphtheria. Suspected respiratory diphtheria requires urgent medical and public-health evaluation. Treatment and infection-control measures may begin before laboratory results are final.

  • A clinician examines the throat, neck, skin, or wounds.
  • A swab may be collected from the throat, nose, or skin lesion.
  • Laboratory testing can identify Corynebacterium diphtheriae.
  • Additional testing may determine whether the bacterium produces diphtheria toxin.
  • Heart and other organ tests may be used to look for complications.

Do not delay care

Get prompt evaluation

Contact a healthcare professional urgently if diphtheria is suspected, and avoid close contact with others while awaiting instructions. Treatment and infection-control precautions may begin before final laboratory confirmation.

Treatment & Management

Diphtheria Treatment and Management

Suspected respiratory diphtheria is a medical emergency requiring hospital or specialist care. Clinicians choose treatment based on where the infection is located and how severe it is. Diphtheria treatment commonly combines antitoxin, antibiotics, supportive care, isolation, and monitoring.

  • Diphtheria antitoxin neutralizes toxin that is still circulating in the body.
  • Antibiotics treat the bacteria and help reduce contagiousness.
  • Airway support may be needed when swelling or a membrane interferes with breathing.
  • Isolation and infection-control precautions help prevent transmission.
  • Monitoring checks for heart, nerve, kidney, and other complications.

Prevention

Diphtheria Prevention

Routine vaccination and recommended booster doses are the most effective way to prevent diphtheria. Check your local immunization schedule or ask a clinician for recommendations tailored to your age, health, vaccination history, and travel plans.

  • Keep routine diphtheria vaccination and booster doses up to date.
  • Ask a healthcare professional about vaccination before travel to an area with ongoing transmission.
  • Wash hands regularly and avoid sharing items contaminated with respiratory or wound secretions.
  • Cover coughs and sneezes and limit close contact when ill.
  • Clean and cover skin wounds and seek care for sores that do not improve.
  • Contact a healthcare professional promptly after a known exposure.

Outlook and Prognosis

Outlook and Prognosis for Diphtheria

Outcomes are generally better when vaccination is up to date and treatment begins promptly. Delayed treatment, respiratory involvement, toxin effects, and underlying health conditions can worsen the prognosis. Recovery may require continued monitoring even after the initial symptoms improve.

  • Respiratory disease may require hospital monitoring even when symptoms begin to improve.
  • Heart or nerve complications can appear during recovery and require follow-up.
  • Follow-up testing may be needed to confirm that the bacteria have been cleared.
  • A person who has had diphtheria may still need vaccination because infection does not reliably provide lasting protection.

When Should You See a Doctor

When Should You See a Doctor for Diphtheria?

Seek care promptly

Get urgent medical advice

Seek urgent medical advice for a sore throat with a gray or white throat coating, neck swelling, painful skin sores with a gray coating, or known close contact with someone who has diphtheria. Call ahead so the healthcare setting can provide infection-control instructions.

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