The Facts

Tonsillitis is an infection of the tonsils that causes inflammation. It's most common in children aged 3 to 7, who have larger tonsils than adults and older children. The tonsils are made of lymphatic tissue. Their job is to produce antibodies that fight infection. Ironically, such tissue is quite prone to becoming infected itself. Tonsillitis can be caused by viral or bacterial infections.

Many cases of tonsillitis never reach the doctor's office. However, it is estimated that 15% of all visits to family doctors are because of tonsillitis.

Tonsillectomy (tonsil removal) has always been the most common childhood operation, but it is considered a last resort for tonsillitis these days.


There are three common causes of tonsillitis:

Group A streptococcus, which are common bacteria that cause throat infections in 1 in 5 people, including adults. Many people have no symptoms but they can still transmit the bacteria. Group A streptococcus can also cause strep throat. It's also capable under some circumstances of causing more serious illness, such as rheumatic fever.

Various respiratory viruses, especially cold and flu viruses, account for most cases of tonsillitis. These infections can be sometimes milder than bacterial infections, but it is often difficult to tell the difference between a viral and bacterial infection.

Infectious mononucleosis, caused by the Epstein-Barr virus, can also produce symptoms of tonsillitis, especially in children.

Symptoms and Complications

The main symptom of tonsillitis is sore throat, but since the throat and ears share the same nerves, the pain is often felt in the ears. The pain is usually worse when swallowing. Very young children may not complain of a sore throat but may simply refuse to eat.

Other symptoms can include:

  • fever
  • general ill feeling
  • tender lymph nodes in the neck
  • headaches
  • vomiting

All forms of tonsillitis clear up without treatment. It usually takes a few days for bacterial or normal viral tonsillitis to clear, but it can take weeks if mononucleosis is the cause. Because of possible complications associated with bacterial tonsillitis, doctors usually give antibiotics.

One complication of bacterial infection, rheumatic fever, used to be common until doctors started treating bacterial tonsillitis with antibiotics. Your own immune response to Group A streptococcus can cause damage throughout the body, especially to the heart. This can cause permanent damage, resulting in heart disease years later. It's now extremely rare in Canada (only a few cases per year), though it is still a major problem in some countries.

Another possible complication from bacterial tonsillitis is a peritonsillar abscesses (quinsy). This occurs when a clump of bacteria are "walled off" by new tissue growth. The abscess is not in the tonsil itself but on one side of it. Unlike simple tonsillitis, quinsy tends to be felt on only one side of the throat, and people with this condition can often be seen tilting their head to one side to reduce pain. Quinsy is more common in young adults with tonsillitis.

Making the Diagnosis

Open your mouth and say "aaah" – when you do, the tonsils can be seen at the back of the throat and will be clearly red and inflamed.

There's a tendency for viruses and bacteria to cause different types of inflammation. The Epstein-Barr virus, for example, often causes tiny red spots on the soft palate. Bacteria may leave a thin white membrane on the tonsils themselves.

None of these symptoms, however, are reliable enough to diagnose the cause of tonsillitis from appearance alone, so often a throat swab is needed. Traditionally, such swabs are then cultured to see what bacteria are present, but there are also rapid tests that can give results in minutes or hours.

Finding group A streptococcus on the tonsils doesn't prove it's causing the inflammation, since so many people carry this bug with no ill effects. A person could be a healthy group A streptococcus carrier, whose tonsillitis is due to a virus.

Blood tests are usually required to diagnose infectious mononucleosis.

Treatment and Prevention

If you have tonsillitis, you should rest and stay well hydrated. You can take acetaminophen* or ibuprofen to ease symptoms, but acetylsalicylic acid (ASA) should be avoided in children with viral infections, as it can lead to Reye's syndrome, a very dangerous condition that affects many organs, particularly the brain and liver.

When bacteria are causing the infection, your doctor will likely prescribe an antibiotic. Most doctors will not prescribe antibiotics until tests confirm that bacteria are the cause. However, people with 3 out of following 4 characteristic symptoms may be treated with antibiotics "up-front" (before culture results are known): fever, discharge from the tonsils, no cough, and tender lymph nodes.

Few children get chronic or recurring infections. When a child has recurring tonsillitis, family members may be tested to see if they're asymptomatic (without symptoms) carriers of group A streptococcus. If so, they may be given antibiotics to ensure that the whole family is streptococcus-free, and to protect the child from reinfection.

If children don't respond to antibiotics, tonsillectomy may be necessary.

Quinsy is usually treated by draining the abscess and antibiotics. Sometimes removing the tonsils is needed to treat quinsy.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.