Medically reviewed by Carina Fung, PharmD, BCPPS

What is tonsillitis?

Tonsillitis1 is an inflammation of the tonsils, two oval-shaped pads of tissue at either side of the back of the throat. Signs and symptoms of tonsillitis include swollen tonsils, sore throat, difficulty swallowing, fever, and tender lymph nodes on the sides of the neck.

Most cases of tonsillitis are caused by infection with a common virus, but bacterial infections may also cause tonsillitis. Children and teenagers2 are much more likely to get tonsillitis than adults are.

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Tonsillitis starts suddenly and usually goes away within one to two weeks. The fever typically goes away before the sore throat does. Tonsillitis may also return several times over the course of a year. It rarely results in complications.

The right treatment for tonsillitis depends on the cause. It's important to get a prompt and accurate diagnosis. Acute tonsillitis is caused by viral infection in 70%–95% of all cases.

Surgery to remove tonsils is rare and usually performed only when bacterial tonsillitis occurs frequently, doesn't respond to other treatments, or causes serious complications3.

Because it is an infection of the tonsils, tonsillitis is different from pharyngitis, which is an infection of the pharynx (back of the throat). Tonsillitis is also different from strep throat, which is an infection specifically caused by Group A Streptococcus (GAS).

Why do swollen tonsils happen?

As viruses and bacteria enter the body through the nose and mouth, they are filtered in the tonsils. Tonsils are the immune system’s first line of defense in preventing infection. This function may make the tonsils particularly vulnerable to infection and inflammation.

Swelling occurs as a sign of infection. Cells in the tonsils release inflammatory mediators4, including bradykinin and prostaglandins that increase blood flow and increase the permeability of blood vessels. It is this permeability that allows white blood cells into the tissue to fight the infection and cause tissue swelling in the process.

The tonsil's role in immunity declines after puberty—a factor that may account for rarer cases of tonsillitis in adults.

What are tonsil stones?

Tonsil stones, also known as tonsilloliths5, are hard white or yellow build ups of bacterial and cellular debris that form in the crevices of the tonsils. These crevices, also known as tonsil crypts6, are pockets in your tonsils where dead cells, mucus, saliva, and food can get trapped.

Tonsil stones may produce no symptoms. They may be associated with bad breath, since bacteria and fungi can feed on this build up. Most tonsil stones are no larger than a grain of rice. Larger tonsil stones, which are rare, may cause a sore throat or trouble swallowing. Most tonsil stones are harmless and rarely cause larger health complications.

Tonsil stones are fairly common and are not contagious. Poor dental hygiene and large tonsils may be potential causes of tonsil stones. Recurring cases of tonsillitis may also cause tonsils stones.

Tonsillitis causes

Tonsillitis is most often caused by common viruses, but bacterial infections can also be the cause.

The viruses7 that can cause tonsillitis include rhinovirus, coronavirus, and parainfluenza viruses. In addition, approximately 1–10% of cases are caused by the Epstein-Barr virus (EBV), the same virus that often causes mononucleosis (or “mono”).

The most common bacterial strain that causes tonsillitis is Streptococcus pyogenes (group A streptococcus), the same bacteria that causes strep throat. Other strains of bacteria that may also cause tonsillitis include Chlamydia pneumonia, Mycoplasma pneumonia, and Hemophilus influenzae.

A virus or bacteria is spread8 through the air in droplets when an infected person breathes, coughs, or sneezes. You may then become infected after breathing in these droplets or getting them on your skin or on objects that come in contact with your mouth, nose, or eyes. You can also pick up the virus or bacteria from a doorknob or other surface.

Risk factors for tonsillitis include:

  • Young age: Tonsillitis most often occurs in children. Tonsillitis caused by bacteria is most common in children ages 5 to 15, while viral tonsillitis is more common in younger children.
  • 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.

Tonsillitis symptoms

Tonsillitis most commonly affects children between preschool ages and the mid-teenage years. Common signs and symptoms of tonsillitis include:

  • Sore throat
  • Red, swollen tonsils
  • White or yellow coating on the tonsils
  • Difficult or painful swallowing
  • Fever 38°C (100.4°F)
  • Swollen, painful glands (lymph nodes) in the neck
  • A scratchy, muffled or throaty voice
  • Bad breath
  • Stiff neck
  • Headache
  • Loss of appetite

If your tonsillitis is from a viral infection, typical cold symptoms such as a cough or a stuffy nose are also likely.

In young children who are unable to describe how they feel, signs of tonsillitis may include:

  • Drooling due to difficult or painful swallowing
  • Stomachache
  • Refusal to eat
  • Unusual fussiness

Tonsillitis is a different condition from tonsil hypertrophy or chronically enlarged tonsils. It's important to get an accurate diagnosis if your child has symptoms that may indicate tonsillitis.

Call your healthcare provider if your child is experiencing:

  • A sore throat that doesn't go away within 24 to 48 hours
  • Painful or difficulty swallowing
  • Extreme weakness, fatigue or fussiness

Get immediate care if your child has any of these symptoms:

  • Difficulty breathing
  • Extreme difficulty swallowing
  • Drooling

Disclaimer: The information on this site is generalized and is not medical advice. It is intended to supplement, not substitute for, the expertise and judgment of your healthcare professional. Always seek the advice of your healthcare professional with any questions you may have regarding a medical condition. Never disregard seeking advice or delay in seeking treatment because of something you have read on our site. RxSaver makes no warranty as to the accuracy, reliability or completeness of this information.

If you are in crisis or you think you may have a medical emergency, call your doctor or 911 immediately.