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Sore throats can have a range of causes. They usually result from an inflammation of the throat caused by cold viruses. This can also affect the palatine tonsils. Often simply referred to as "tonsils," these are the visible lumps of tissue on the left and right sides at the back of the throat. Bacterial infections of the tonsils are less common. But it isn’t easy to tell what kind of germs are responsible for the infection. Children and teenagers are much more susceptible to tonsillitis (inflammation of the tonsils) than adults are.

Tonsillitis starts suddenly and usually goes away again within one to two weeks. But it may also return several times over the course of a year. Although that can be unpleasant, it only rarely results in complications.

It's important to distinguish between tonsillitis and tonsil hypertrophy (chronically enlarged tonsils). These are two separate medical conditions. In tonsil hypertrophy, the adenoids may be affected as well.


Red, swollen tonsils.

White or yellow coating or patches on the tonsils.

Sore throat.

Difficult or painful swallowing.


Enlarged, tender glands (lymph nodes) in the neck.

A scratchy, muffled or throaty voice.

Bad breath.


Tonsillitis is most often caused by common viruses, but bacterial infections also can be the cause. The most common bacterium causing tonsillitis is Streptococcus pyogenes (group A streptococcus), the bacterium that causes strep throat. Other strains of strep and other bacteria also may cause tonsillitis.

Risk factors

Young age. Tonsillitis most often affects children, and tonsillitis caused by bacteria is most common in children ages 5 to 15.

Frequent exposure to germs. School-age children are in close contact with their peers and frequently exposed to viruses or bacteria that can cause tonsillitis.

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If you don’t take a full course of antibiotics or the antibiotics don’t kill off the bacteria, it’s possible that complications could develop from tonsillitis. These include rheumatic fever and poststreptococcal glomerulonephritis, as well as:

Obstructive sleep apnea (OSA). People who experience chronic tonsillitis may start to experience obstructive sleep apnea. This happens when the airways swell and prevent a person from sleeping well, which can lead to other medical issues without treatment.

Tonsillar cellulitis. It’s also possible the infection will worsen and spread to other areas of the body. This is known as tonsillar cellulitis.

Peritonsillar abscess. The infection can also cause a person to develop a buildup of pus behind the tonsils, called a peritonsillar abscess. This can require drainage and surgery.


While you can’t totally prevent tonsillitis, there are things you can do to reduce your risk. For example:

Wash your hands often, especially before touching your nose or mouth.

Avoid sharing food, drink, or utensils with someone who’s sick.

Replace your toothbrush regularly.