What causes swollen tonsils?

What causes swollen tonsils?

Viral and bacterial infections can cause swollen tonsils, such as tonsilitis and strep throat. Most infections go away on their own but serious bacterial infections can need to be treated with antibiotics.

Within this article we address the common causes of enlarged tonsils and their care. They explain when to see a physician, too.

Swollen tonsils pictures


Some viral and bacterial infections can cause swollen tonsils. Including:

Acute tonsilitis

Viruses and bacteria can invade the tonsils, causing swelling and exudation — a gray covering that covers the tonsils. Many signs can include headache , fever, tiredness, weak breath, and lack of appetite. When only one tonsil is contaminated, a person can experience swelling only on one side of the throat.

People may be taking antibiotics to treat serious infections with bacterial tonsilitis. Nonetheless, a doctor may prescribe surgery to remove the tonsils if they develop tonsillitis more than five times a year.

Over-the-counter ( OTC) medications, such as acetaminophen or ibuprofen, can help relieve symptoms, including headache, sore throat and fever, until the infection is gone.

Strep throat

Streptococcus pyogenes can infect the throat and cause inflammation and swelling of the tonsils. Some people may have other effects, such as headaches and stomach pain, too.

Doctors treat serious cases of strep throat with antibiotics — usually penicillin or amoxicillin — but people who are resistant to such antibiotics will get alternative therapies.

Viruses may also cause strep throat with very different associated symptoms, including cough, runny nose and ulcers in the mouth.


The Centers for Disease Control and Prevention (CDC) states that many types of adenoviruses, including colds, pneumonia and bronchitis, cause respiratory infections.

Adenoviruses may also cause chronic tonsil infections in people with a compromised immune system, although symptoms do not always appear in such infections. Because most adenoviruses are mild, people usually don’t need medication, and the virus will go away on its own.

Epstein-Barr virus

The signs of an infection with the Epstein-Barr virus, such as mononucleosis, include swollen tonsils, cough, weakness and skin rashes. Adults and adolescents typically recover within 2–4 weeks, although symptoms such as fatigue can continue for several weeks or months in some instances.

There is no Epstein-Barr Virus Vaccine. Nevertheless, because the virus can spread through the exchange of body fluids, particularly saliva, it can also be prevented by people keeping a distance from people who have the virus and not sharing toothbrushes and drinks.

When a person has the virus it will stay in an inactive state in the body but can reactivate throughout their life at certain times.


Flu may cause swollen tonsils and other symptoms, such as cough, a sore throat, body aches and, in some cases, fever. The symptoms may unexpectedly come on. Flu complications can include pneumonia, so if their symptoms do not improve after a week, it is important that people get in contact with their doctor.


The measles virus can cause swollen tonsils on the inside of the mouth, high fever , cough, and small white spots, typically 2–3 days after symptoms start.

Other symptoms include facial rash and upper neck rash. Children who did not have a measles vaccine are at greatest risk of catching it and developing complications. When a parent or caregiver believes their child has measles, they should talk to a doctor at the earliest opportunity.


A tonsil infection — for instance, acute tonsilitis — may have severe complications. Therefore it is important to urgently contact a doctor for symptoms that include:

  • difficulty speaking and swallowing
  • trouble breathing
  • an inability to open the mouth
  • a severe and worsening sore throat

Are swollen tonsils a symptom of cancer?

Swollen tonsils can in rare cases be a symptom of cancer. Oropharyngeal cancers are the ones found in the head and neck.

Cancerous lumps on the tonsils do not have fever but cancer-related symptoms include:

  • a sore throat
  • difficulty swallowing, chewing, or breathing
  • earache
  • unexplained weight loss
  • a lump in the neck or throat

Cancer, however, is a fairly rare cause of swollen tonsils. About 53,260 people in the United States will develop oral or oropharyngeal cancer by 2020, according to the American Cancer Society.

Why do tonsils get infected?

The tonsils are masses of soft tissue at the back of the throat, and are exposed to germs that enter the mouth. They have the job of filtering out pathogens before they get into the body.

The high exposure to germs from outside the body presents an elevated risk of infection for the tonsils.


Swollen tonsils treatment will depend on cause.

Usually a doctor will prescribe antibiotics for severe bacterial infections. Viral diseases are more difficult to treat. Some antiviral drugs can function but their efficacy will depend on the infection type and severity.

Viral infections can get better themselves in most cases. OTC drugs might help relieve other accompanying symptoms such as headache, sore throat, and fever.

A doctor may prescribe removal of the tonsils for recurrent tonsil infections, usually more than five a year.

Home remedies

People can try using home remedies to ease the symptoms. These include:

  • drinking cold drinks or sucking on ice cubes
  • staying hydrated
  • resting
  • gargling warm salt water
  • sucking on lozenges
  • avoiding smoking and limiting exposure to other substances that irritate the throat
  • using a humidifier to keep the air moist
  • breathing in steam from hot water

When to see a doctor
After a few days, most cases of swollen tonsils will go away all by themselves. OTC medications and home remedies can help relieve some of the symptoms.

If the swollen tonsils worsen or don’t get better after a few days, a person should see a doctor. If the patient is unable to breathe, emergency medical treatment is necessary.


Swollen tonsils are typically the result of a viral or bacterial infection. Depending on the cause of the infection a person can expect to recover to several weeks within a few days.

Many individuals can experience tonsil infections and swelling on a regular basis. For such cases a doctor might recommend that the tonsils be removed.


Preventing swollen tonsils isn’t always easy, but some measures to lower the risk of infection include:

  • maintaining good personal hygiene
  • avoiding close contact with people who are sick
  • avoiding smoking
  • washing the hands regularly
  • staying up to date with any vaccinations that a doctor recommends


The primary causes of swollen tonsils are bacteria and viruses, but in some cases swollen tonsils can be a sign of cancer.

Tonsil infections usually go away after a couple of days, and OTC medications and home remedies can help alleviate some of the symptoms.

Doctors may consider treating more serious antibiotic or antiviral infections.