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Tonsillitis refers to the inflammation of the tonsils in the throat. Tonsillitis may either be acute or chronic. A general practitioner (GP) typically sees around 120 people in a 2,000-patient population with an acute sore throat every year.1 Often presenting first as a sore throat to GPs, chronic tonsillitis generally has an incidence of 100 per 1,000-patient population in the UK.2 Among these patients, children and young adults, aged 5 to 24 years old, have the highest incidence, representing 50% of total cases.3 Annually, there are approximately 37,000 childhood tonsillectomy operations in the UK, costing the NHS approximately £42 million.4,5
Anatomy of the oral cavity
The tonsils are part of the ring-shaped lymphoid tissue in the oropharynx, known as Waldeyer’s ring. Waldeyer’s ring consists of four main groups of tonsils: adenoid, tubal, palatine and lingual. In clinical practice, tonsillitis usually refers to the inflammation of the palatine tonsils, which are located in the lateral walls of the oropharynx.6 Irrespective of size, the palatine tonsils should be visible on examination, unlike the others.
Causes of tonsillitis
Tonsillitis may be acute or chronic (repeated acute infections). An episode of acute tonsillitis can be caused by either a viral (more common) or bacterial infection.7 There are also non-infectious causes of tonsillitis.
Common viral causes include:8
Rhinovirus (most common)
Epstein Barr Virus (EBV)
Common bacterial causes include:
Group A beta-haemolytic Streptococcus (GABHS; most common)
Non-infectious causes include:
Gastro-oesophageal reflux disease
Physical irritation (e.g. from nasogastric tubes)
Ask questions relating to symptoms outlined in CENTOR and FeverPAIN criteria (Tables 2 & 3).
Typical symptoms of tonsilitis include:
Pain and malaise
Lesscommon symptoms include:
Typical clinical findings:
Swollen, erythematous palatine tonsils
Tonsils covered with exudate
Less common clinical findings:
Peritonsillar abscess (usually a complication of acute tonsillitis) – unilateral bulge above tonsils, accompanied by symptoms such as a sore throat, dysphagia, trismus and a classical hot potato voice.
The clinical presentation of tonsillitis may mimic several other conditions. The key differentiating features between these diagnoses are presented in Table 1.
Table 1. Differential diagnoses of tonsillitis, and their distinguishing features
Features differentiating from tonsillitis
Acute and severe onset
Infection mononucleosis (glandular fever) due to Epstein Barr Virus
Pharyngitis of longer duration
FBC – raised WBC count with lymphocytosis
Positive Monospot test (in patients > 4 years old)
Squamous cell carcinoma
Unilateral tonsillar enlargement
An acute episode of tonsillitis is traditionally diagnosed using clinical features alone. During this process, it is key for clinicians to identify whether tonsillitis is of viral or bacterial aetiology. This will allow for the appropriate prescription of antibiotics. This may be done with the help of the CENTOR (Table 1) and FeverPAIN criteria (Table 2).
Table 2. CENTOR criteria, indicating the likelihood of a bacterial (GABHS) tonsillitis. Scores are totalled from 0-49
Symptoms of tonsillitis
Tender anterior cervical lymphadenopathy
History of fever (>38°C)
Absence of cough
A score of 0-2 has a low probability of a GABHS infection and should be managed conservatively.
A score of 3-4 has a higher probability of a GABHS infection and should be treated with an antibiotic prescription.
Table 3. The FeverPAIN criteria consist of five symptoms of acute tonsillitis, each scoring 1 point, indicating the likelihood of a bacterial (GABHS) tonsillitis, scoring 0-5.9
Symptoms of tonsillitis
Fever (during previous 24 hours)
Purulence (pus on tonsils)
Attend rapidly (within 3 days after symptoms’ onset)
Severely inflamed tonsils
No cough or coryza (inflammation of mucous membranes in the nose)
A score of 0-1 indicates a low possibility of GABHS infection and should be managed conservatively.
A score of 2-3 indicates a moderate possibility of GABHS infection. These patients can be either managed conservatively or given a delayed antibiotic prescription to use if symptoms do not resolve within three to five days or if they deteriorate.
A score of 4-5 suggests a high possibility of GABHS infection and should be managed with antibiotics.
Laboratory testing is not routinely performed as tests have no role in the diagnosis or management of tonsillitis. However, lab investigations may be useful in confirming a history of GABHS infection in patients with other conditions linked to GABHS, such as rheumatic fever and heart disease.
Examples of such investigations include:
Throat swab for culture (to detect the presence of bacteria)
Rapid streptococcal antigen test (to identify the presence of GABHS)
Monospot test for EBV
The overall management of tonsillitis can be broken down into acute and chronic management.
Supportive: hydration, fluids, ibuprofen ± paracetamol and rest
Phenoxymethylpenicillin (Penicillin V) for 10 days.
If allergic to penicillin, clarithromycin or erythromycin for 5 days. Consult your local BNF for appropriate doses.
It is important to note that amoxicillin should be avoided as it can cause a generalised rash in patients who have EBV.
NICE advises that certain patients with recurrent episodes of tonsillitis, who meet any of the following criteria,9 can be referred for tonsillectomy (surgical removal of the tonsillar glands8):
More than 7 documented, adequately treated, sore throat episodes in 1 year
More than 5 episodes in 2 years
More than 3 episodes in 3 years
For whom there is no other explanation for recurrent symptoms
There are multiple problems that can arise if tonsillitis is not appropriately identified and treated, including:
Otitis media (most common)
Peritonsillar abscess (quinsy) – presents with difficulty swallowing, trismus (difficulty in opening the mouth due to spasm or pain), and airway compromise
Scarlet fever – caused by Streptococcus pyogenes (a form of GABHS), causing a rash on the chest or axillae following a sore throat and fever. Scarlet fever is traditionally known for its’ ‘strawberry tongue’ sign (Figure 3).
Tonsillar haemorrhage is an ENT emergency, requiring immediate from an ENT surgeon and anaesthetist.
Primary haemorrhage (within 24 hours)
Secondary haemorrhage (after 24 hours, usually 5-10 days post-operatively) – due to infection of the tonsillar fossa
Tonsillitis refers to inflammation of the tonsillar glands, mainly the palatine tonsils.
It is usually caused by a viral infection.
Clinically, the CENTOR and FeverPAIN criteria can be used by clinicians to distinguish between a viral and bacterial source of infection.
Most common reported symptoms include sore throat, cough and a coryzal prodrome.
Most common examination findings include fever, swollen, erythematous palatine tonsils, cervical lymphadenopathy and tonsillar exudate.
Medical management includes pain relief if viral, and phenoxymethylpenicillin (Penicillin V) if bacterial (depending on patient allergies).
Complications of tonsillitis include otitis media, peritonsillar abscess and scarlet fever.
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Color Atlas of Oral and Maxillofacial Diseases – Bacterial Infections. Published in 2019. Available from: [LINK]
New England Journal of Medicine (NEJM) Acute pharyngitis. Published in 2001. Available from: [LINK]
Oxford Handbook of Clinical Specialties 10th Ear, Nose and Throat. Published in 2016. Available from: [LINK]
National Institute for Health and Care Excellence (NICE). Sore throat – acute. Published in 2018. Available from: [LINK]
British Medical Journal (BMJ) Best Practice. Tonsillitis. Published in 2019. Available from: [LINK]