What Causes Swollen Tonsils?


Woman having pain with a sore throat.
Swollen Tonsils. Stockbyte/Getty Images

To understand what causes swollen tonsils, or tonsillitis, you must first understand what tonsils are. The tonsils are part of the lymphatic system, which is responsible for ridding the body of toxins and other substances the body wants to get rid of. This system is also responsible for helping to protect your body 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.

Causes of Tonsillitis

While the tonsils serve as a front line defense from respiratory infections, occasionally the tonsils will actually become infected by the bacteria and viruses. Common infections that cause tonsillitis include:

Non-infectious causes of swollen tonsils are more rare, but may include:

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

Symptoms of Tonsillitis

The most common symptom, and the biggest reason for seeking medical attention, related to swollen tonsils is a sore throat. Other common symptoms include:

  • odynophagia (painful swallowing)
  • dysphagia (difficulty swallowing)
  • redness at the site of your tonsils
  • pockets or patches of white on the tonsils (known as exudates)
  • other lymph node enlargement
  • fever
  • headache
  • fatigue
  • petechiae, or small red or purple spots on the roof of your mouth.

While there are many symptoms that can be related to tonsillitis, you are not likely to experience all of them.

In fact the set of symptoms you experience will actually help your doctor to identify what is causing your swollen tonsils.

Complications Related to Tonsillitis

Typically the symptoms related to tonsillitis are just annoying, requiring no intervention. If you have a viral infection, which is often the case, no treatment is required. If your symptoms are bad enough, your doctor may prescribe you medications to treat your symptoms but will not provide you with an antibiotic if a virus is suspected.

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. Occasionally strep infections can become chronic and difficult to cure. Chronic strep infections sometimes make surgical removal of the tonsils necessary.

In some cases, tonsils may become so swollen that it may interfere with breathing or swallowing or cause obstructive sleep apnea. Sleep apnea is a serious condition that causes a person to stop breathing for a brief period of time while sleeping. Studies have shown that sleep apnea can lead to daytime fatigue, depression, mood swings and more serious health conditions including high blood pressure and heart disease.

Obstructive sleep apnea is also a leading indication for tonsillectomies in the United States.

Treatment for Tonsillitis

Swollen tonsils caused by bacterial infections can be treated with antibiotics. Symptoms usually go away within a few 24 hours after starting medication. Antiviral medications are not typically prescribed for most cases of swollen tonsils. Antivirals unlike antibiotics  do not actually kill a viral infection but slow down the spreading of the virus. This allows your body to fight the viral infection.

In some cases it may be possible to reduce your swollen tonsils using steroid medications.

However, since steroid medications have many side-effects most doctors are hesitant to prescribe these medications unless the tonsils are extremely swollen and bothersome.


American Academy of Otolaryngology - Head and Neck Surgery. Fact Sheet: Tonsillitis. Accessed: January 22, 2011 from http://www.entnet.org/HealthInformation/tonsillitis.cfm

Medscape. Tonsillitis and Peritonsillar Abscess. Accessed: April 30, 2016 from http://emedicine.medscape.com/article/871977-overview#a6

Medline Plus. Tonsillitis. Accessed: January 22, 2011 from http://www.nlm.nih.gov/medlineplus/ency/article/001043.htm

National Sleep Foundation. Sleep Apnea. Accessed: April 30, 2016 from https://sleepfoundation.org/sleep-disorders-problems/sleep-apnea

Yellon, RF & Chi, DH. (2012). Atlas of Pediatric Physical Diagnosis: Otolaryngology. Philadelphia, PA: Saunders/Elsevier.

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