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Tonsillitis is a common throat infection that affects both children and adults. It is usually caused by viruses, but can sometimes be due to bacteria such as Group A Streptococcus (Strep A). This guide explains what tonsillitis is, the key symptoms to watch for, how it is diagnosed, and the most appropriate treatment options, including when surgery may be considered.

What is tonsillitis?

The tonsils are two small pads of lymphoid tissue located on either side at the back of the throat. They form part of the immune system and help protect the body by producing antibodies against germs that enter through the mouth or nose. When the tonsils themselves become infected, they swell and become inflamed, resulting in tonsillitis.

Tonsillitis is typically divided into two main types:

• Acute tonsillitis: a sudden, occasional infection.
• Recurrent tonsillitis: repeated infections that keep returning over time.

Causes of tonsillitis

Viral infections are by far the most common cause of tonsillitis. Many people assume that a sore throat with white patches must mean a bacterial infection, but viruses can cause equally significant symptoms. Bacterial tonsillitis is less common but important to identify; it is most often caused by Group A Streptococcus (Streptococcus pyogenes), commonly known as strep throat.

Distinguishing between viral and bacterial causes is crucial because they are managed differently.

Common symptoms of tonsillitis

Symptoms vary depending on age and the cause, but typical features include:

• sore throat
• pain or difficulty swallowing
• high temperature (fever) and chills
• headache
• earache
• hoarseness or loss of voice
• swollen and tender lymph nodes in the neck
• white patches or pus on the tonsils

In children, additional symptoms such as abdominal pain, nausea or refusal to eat may occur. Symptoms usually develop over 1–2 days and most cases improve within a week.



Diagnosis: why a throat swab may be needed

A clinician will usually start with a clinical assessment based on symptoms and a careful examination of the throat and neck. To help decide whether antibiotics are likely to help, they may use scoring tools such as the FeverPAIN or Centor criteria. Where indicated, a throat swab will be taken to test for streptococcal bacteria. A blood test is occasionally performed if glandular fever (infectious mononucleosis) or another condition is suspected.

These assessments help avoid unnecessary antibiotic use while ensuring bacterial infections are treated promptly.

Treatment options

Treatment depends on the cause and severity of symptoms.

• Viral tonsillitis (the majority of cases): This usually improves with supportive care at home: rest, plenty of fluids, pain relief with paracetamol or ibuprofen (following age-appropriate dosing), and soft or cool foods and drinks to ease swallowing. Throat lozenges or sprays may provide additional comfort.
  
  
• Bacterial tonsillitis: If Group A Streptococcus is confirmed or strongly suspected, a course of antibiotics (usually penicillin V for 10 days) will be prescribed. In rare severe cases where swallowing is extremely difficult, antibiotics may need to be given by injection or intravenously in hospital.

For children or adults with frequent recurrent tonsillitis that significantly affects quality of life, surgery to remove the tonsils (tonsillectomy) may be considered. This is usually discussed if there have been:

• 7 or more well-documented episodes in one year, or
• 5 or more episodes per year for two consecutive years, or
• 3 or more episodes per year for three consecutive years (known as the Paradise criteria).

When to seek medical advice

Contact a GP promptly if you or your child experiences:

• persistent high fever that does not respond to paracetamol or ibuprofen
• severe difficulty swallowing, drooling or inability to drink fluids
• breathing difficulties or noisy breathing
• severe one-sided throat pain or neck swelling
• inability to open the mouth fully
• a rash (which may suggest scarlet fever)
• symptoms not improving after 3–4 days or getting worse

Early assessment ensures the correct cause is identified and appropriate support is given, helping to speed up recovery and prevent complications.