What causes tonsillitis?

Most cases of tonsillitis are caused by a virus (80%). The viruses that cause colds (rhinovirus), flu (influenza virus), and laryngitis and croup (parainfluenza virus) are some of the viruses that can cause tonsillitis.

The bacteria (Streptococcus pyogenes) that cause a sore throat (or ‘strep’ throat) can also cause tonsillitis. You can have both a throat infection (pharyngitis) and tonsillitis at the same time.

You can catch tonsillitis in the same way as you can catch a cold or the flu. The cold or flu viruses are spread when someone infected with the virus sneezes or coughs, releasing droplets that contain the virus into the air. These droplets can be breathed in by others, or transferred to anyone who touches a surface contaminated with droplets containing the virus.

Find out more about how to prevent infection, and the symptoms, medicines and treatments for tonsillitis.