What causes a throat infection?

A sore throat (throat infection, pharyngitis) is caused when a virus (or bacteria) infects the area at the back of your throat (pharynx). This causes redness and swelling (inflammation), and can be painful, especially when you swallow.

Most throat infections are caused by viruses, including the same viruses that cause:

Bacteria can also cause a throat infection. This is sometimes called a ‘strep’ throat, after the name of the bacteria that cause it — Streptococcus pyogenes. Bacterial infections or ‘strep’ throat is rare in children younger than 3 years old. About 1 in 3 children aged 3–14 years will have a sore throat caused by S. pyogenes, compared with about 1 in 10 adults.

You can catch a throat infection when someone infected with the virus or bacteria sneezes or coughs, releasing droplets that contain the virus into the air. These droplets can be breathed in by others, or picked up by anyone who touches a contaminated surface.

Find out more about the symptoms, and treatment of sore throats as well as how to prevent infections.

  • Antibiotic Expert Group. Therapeutic guidelines: Antibiotic; Pharyngitis and/or tonsillitis. Melbourne: Therapeutic Guidelines Ltd; 2012.
  • NHS Choices. Sore throat — causes. London: NHS, 2010.
    www.nhs.uk/Conditions/Sore-throat/Pages/Causes.aspx (accessed 4 May 2012).