Tonsillitis refers to the acute inflammation of the palatine tonsils secondary to infection.

Acute tonsilitis is very common, especially in children. It is most frequently viral and associated with an upper respiratory tract infection (URTI). It may also be caused by bacteria (e.g. Group A Streptococci).

Management typically involves reassurance, fluids and analgaesia. Where a bacterial cause is suspected, antibiotics +/- steroids are given. The most common complication of acute tonsillitis is peritonsillar abscess (see Quinsy). Recurrent severe tonsillitis results in considerable morbidity, particularly time lost from school or work.


Clinical features

Clinical examination typicaly demonstrates enlarged and erythematous tonsils.

Exudate is more uncommon and typically suggests a bacterial pathogen, with Group A beta-haemolytic streptococcus (GABHS) being the most common bacterial cause.

However, care should be taken to exclude infectious mononucleosis (Epstein-Barr virus), which can also result in an exudative tonsilitis. These may be distinguished by lymphadenopathy which should be limited to the anterior chain in a simple bacterial tonsilitis, whilst is more generalised with infectious mononucleosis.


  • Fevers
  • Sore throat
  • Dysphagia
  • Trismus (difficulty opening the mouth)
  • Malaise


  • Enlarged and inflammed tonsils
  • White exudate on tonsils
  • Lymphadenopathy

Tonsillitis clinical features

Centor criteria

The Centor criteria is used to guide antibiotic use in those presenting with sore throat and tonsillitis. 

Evaluate the patient for the following:

  • Tonsillar exudate
  • Tender anterior cervical lymphadenopathy or lymphadenitis 
  • History of fever (over 38°C)
  • Absence of cough

Each is worth one point, the higher the score the greater the chance the illness is caused by GABHS. 


Management depends on the severity of the tonsillitis and any underlying conditions that may impact the conditions clinical course.

Simple tonsillitis

A common cause of presentation in primary care. Most patients can be managed with antipyretic analgesia.

Those with a Centor score of 0-2 should not routinely be offered antibiotics. Those with a score of 3-4 may be offered antibiotics though the evidence shows minimal overall benefit from antibiotics. 

Many offer a ‘back-up’ prescription that can be used if symptoms persist for longer than 3-5 days. Phenoxymethylpenicillin is the first-choice antibiotic, clarithromycin or erythromycin may be used in those with penicillin allergy. Consider a lower threshold for antibiotics in patients at increased risk of rheumatic fever.

Severe tonsillitis

Symptoms may be severe with dysphagia and high fevers. Some patients benefit from IV fluid, antibiotics and a dose of IV steroids. If severe they may be admitted overnight for observation and reassessed after 12-24 hours of IV therapy. 

Note: In patients presenting with any of a severe sore throat, drooling, stridor or trismus – epiglottitis – a rare but potentially life-threatening condition should be considered. 

Special cases

Additional care is required in certain patient groups at increased risk of severe infections.

  • At risk of agranulocytosis (e.g. taking carbimazole): hold medication, send FBC and seek specialist advice.
  • Immunosuppressed patients: may be due to an illness (e.g. haematological malignancy, HIV/AIDS) or due to medications (e.g. chemotherapy, immunosuppressants post-transplant). Complete a clinical review and seek specialist advice.


Complications are rare but may be seen in bacterial tonsillitis.

Rarely GABHS is associated with complications, these may be suppurative or non-suppurative.

Complications of bacterial tonsillitis


  • Quinsy (peri-tonsillar abscess)
  • Acute sinusitis
  • Acute otitis media


  • Acute rheumatic fever
  • Acute glomerulonephritis


The NHS sets specific criteria that should be met for tonsillectomy to be considered.

The NHS will normally fund tonsillectomy where:

  • Malignancy is suspected
  • More than one episode of quinsy or airway obstruction
  • Recurrent sore throat with disabling episodes preventing normal function, due to tonsillitis (seven or more eligible episodes in the last year or five or more in each of the last two years or three or more in each of the preceding three years)
  • Obstructive sleep apnea

As always these criteria do not overrule clinical judgment and a holistic view of each patient and their presentation must be considered.

Note: Eligible episodes must score 3 or 4 in the Centor criteria.

Additionally, in children tonsillectomy (+/- adenoidectomy) may be considered where:

  • Failure to thrive
  • Sleep apnoea 
  • Significant impact on quality of life


Updated: May 2020 by Benjamin Smeeton

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