To understand what causes swollen tonsils you must first understand what tonsils are. It is believed that the tonsils are part of the lymphatic system and help to protect against viruses and bacteria. After being trapped by the tonsils, inhaled particles are then transported to the lymphatic system and disposed of by the immune system. However, occasionally there is a glitch in the system. Sometimes, the tonsils become infected by the bacteria and viruses. This causes swelling, redness, pain, and in some cases white or red spots on the tonsils. Common infections that cause swollen tonsils include:
Because complications of strep throat can be serious, you should see a doctor to have a strep test if you have swollen tonsils, especially if they are accompanied by redness and throat pain. It is also interesting to note that a condition called cryptic tonsils can make it appear as though there are white spots of pus on the tonsils even though the tonsils are not really infected.
Swollen tonsils caused by bacterial infections can be treated with antibiotics. Symptoms usually go away within a few days after starting medication. There is no medication that can kill a viral infection but it may be possible to reduce your swollen tonsils using steroid medications. However, there are side effects.
In some cases tonsils may become so swollen that it may interfere with breathing or swallowing. If this does not go away, or in cases or recurrent strep throat or sleep apnea, the tonsils may have to be surgically removed.
American Academy of Otolaryngology - Head and Neck Surgery. Fact Sheet: Tonsillitis. Accessed: January 22, 2011 from http://www.entnet.org/HealthInformation/tonsillitis.cfm
Medline Plus. Tonsillitis. Accessed: January 22, 2011 from http://www.nlm.nih.gov/medlineplus/ency/article/001043.htm