Diphtheria bacteria: what to know

Diphtheria is caused by bacteria that can settle in the nose or throat and, in some strains, produce a toxin. The toxin can injure local tissue and may affect the heart, nerves, or kidneys. A thick coating in the throat, sore throat, hoarseness, swollen neck, and weakness can occur, but symptoms vary. A sore throat is a common presentation of several illnesses and does not by itself establish diphtheria. The bacteria can spread through respiratory droplets and close contact, which is why suspected cases require clinical and public-health guidance.

Seek medical advice promptly if diphtheria is suspected or you have had close contact with a confirmed case. Avoid close contact with others until a clinician advises you, and share vaccination and travel details. Treatment may include antitoxin, antibiotics, monitoring, and contact measures; antibiotics are explained in [Antibiotic Treatment](/treatments/medical-management/antibiotic-treatment/). Vaccination is the main preventive tool; see [Childhood Immunisation](/treatments/preventive-care-and-vaccination/childhood-immunisation/).

Call emergency services for trouble breathing or swallowing, drooling, rapidly increasing neck swelling, faintness, severe weakness, or a rapidly worsening throat illness. Do not try to scrape a throat coating away. Even without severe symptoms, possible exposure or an unusual sore throat warrants prompt assessment. More symptom context is available at [Sore Throat](/symptoms/sore-throat/).

Ask whether testing, treatment, temporary separation, or contact tracing is needed. Confirm whether household members need assessment or vaccination, and review your own immunisation record and follow-up plan.