Tonsillitis - Causes 

It is estimated that around 8 out of 10 cases of tonsillitis are caused by a viral infection.

Viruses known to cause tonsillitis include:

• rhinoviruses – which are viruses that cause the common cold
• the influenza virus
• parainfluenza virus – which causes laryngitis and croup
• enteroviruses – which cause hand, foot and mouth disease
• adenovirus – which is a common cause of diarrhoea
• the measles virus

In rare cases, tonsillitis can be caused by the Epstein-Barr virus, which is the virus that causes glandular fever. If this is the case, you will probably feel very ill. You may have swollen lymph nodes (glands) throughout your body and an enlarged spleen.

Bacterial tonsillitis

Bacterial tonsillitis may be caused by a number of different bacteria, but is usually caused by group A streptococcus bacteria.

In the past, serious bacterial infections, such as diphtheria and rheumatic fever, have been associated with tonsillitis, but this is now very rare due to vaccination and improved treatment of these diseases.

How you catch tonsillitis

Tonsillitis is spread in the same ways as colds and flu. It's contained in the millions of tiny droplets that come out of the nose and mouth when an infected person sneezes or coughs. You can then become infected with the virus by breathing in these droplets from the air.

You can also become infected by handling a surface or object that these droplets have landed on and then touching your face.