Tonsillitis is an infection or inflammation of the tonsils. The tonsils are part of the immune system and appear as balls of tissue located on either side of the back of the throat, above and behind the tongue.

Tonsillitis is most often caused by a virus. However, it also can be caused by the same bacteria that cause strep throat. The most common symptom of tonsillitis is a sore throat. When examined, the throat may look red and swollen. Additional symptoms such as fever, nasal congestion, and swollen lymph nodes are not uncommon.

Tonsillitis will usually go away on its own. Home treatment measures such as gargling with salt water, drinking warm tea, and taking nonprescription pain medication can help relieve discomfort. Bacterial tonsillitis is often treated with antibiotics to prevent complications, such as rheumatic fever. Surgical removal of the tonsils (tonsillectomy) is sometimes considered as treatment for tonsillitis.