The tonsils are two small glands that sit on either side of the throat. In young children they help fight germs and act as a barrier against infection.

Tonsillitis is inflammation of the tonsils. It's usually caused by a viral infection or, less commonly, a bacterial infection.

It's a common type of infection in children, although it can sometimes affect adults.

The symptoms of tonsillitis include:

• sore throat that can feel worse when swallowing
• high temperature (fever) over 38C (100.4F)
• coughing
• headache
• Symptoms usually pass within three to four days.

When the tonsils become infected they isolate the infection and stop it spreading further into the body. As a child's immune system develops and gets stronger, the tonsils become less important and usually shrink. In most people, the body is able to fight infection without the tonsils.

Removal of the tonsils will usually only be recommended if they're causing problems such as severe or repeated episodes of tonsillitis (see below).

What causes tonsillitis?

Most cases of tonsillitis are caused by a viral infection, such as the viruses that cause the common cold or flu virus (influenza).

Some cases can also be caused by a bacterial infection, typically a strain of bacteria called group A streptococcus bacteria.

These types of infections spread easily, so it's important to try to avoid passing the infection on to others by:

• staying away from public places, such as work, school or nursery until your GP says it's safe to return (this will usually be after the symptoms have passed)
• coughing and sneezing into a tissue and disposing of the tissue
• washing hands before eating, after going to the toilet and, if possible, after coughing and sneezing

When to see your Doctor ?

Tonsillitis isn't usually a serious condition. You only need to see your GP if symptoms:

• last longer than four days and don't show any signs of improvement
• are severe – for example, if you're unable to eat or drink due to the pain, or you have difficulty breathing

Your GP will examine your throat and ask you some questions about your symptoms.

There are four main signs that tonsillitis is caused by a bacterial infection rather than a viral infection. They are:

• a high temperature
• white pus-filled spots on the tonsils
• no cough
• swollen and tender lymph nodes (glands)

Further testing may be recommended if you have at least two of the above signs. If you have three, it's highly likely that you have bacterial tonsillitis

In most cases, tonsillitis gets better within a week. However, a small number of children and adults have tonsillitis for longer or it keeps returning. This is known as chronic tonsillitis and surgical treatment may be needed.

Surgery to remove the tonsils (a tonsillectomy) is usually only recommended in cases where there have been several severe episodes of tonsillitis over a long period of time, or if repeated episodes disrupt normal activities.

Complications of tonsillitis Complications of tonsillitis are rare and usually only occur if it's caused by a bacterial infection. They're usually the result of the infection spreading to another part of the body, such as the middle ear (otitis media).