ENT

Tonsillitis

Acute sore-throat inflammation involving the tonsils, usually viral and self-limiting; clinical scoring targets antibiotics to people more likely to benefit while airway compromise, quinsy and deep-neck infection require urgent escalation.

Definition

Tonsillitis is acute inflammation of the palatine tonsils, usually as part of a viral or bacterial acute sore throat. Most cases are self-limiting; antibiotic decisions should follow clinical severity and FeverPAIN or Centor assessment.

Epidemiology

Acute sore throat and tonsillitis are common in children, adolescents and adults. Most cases are viral. Group A streptococcus causes a minority but clinically important proportion, especially in school-aged children and young adults.

Pathophysiology

Viral or bacterial infection triggers tonsillar mucosal inflammation, oedema, exudate and reactive cervical lymphadenopathy. The same local inflammation can extend into the peritonsillar or deeper neck spaces, producing quinsy or deep-neck infection. Epstein-Barr virus causes glandular fever with prominent systemic and lymphoid features and a characteristic prescribing hazard with amoxicillin.

First principles

Tonsillitis is usually part of an acute viral sore throat

The palatine tonsils are lymphoid tissue exposed to the oropharynx, so viral upper-respiratory infection commonly produces erythema, swelling, exudate and painful swallowing. Group A streptococcus is an important bacterial cause, but exudate alone cannot reliably distinguish it from viral disease.^1,2

Clinical scores estimate antibiotic benefit rather than prove a pathogen

FeverPAIN and Centor combine features associated with streptococcal infection, including fever, purulence or exudate, tender anterior cervical nodes and absence of cough. They are decision aids for antibiotic strategy; they do not replace assessment of severity, alternative diagnoses or the airway.^1,2

Glandular fever can look bacterial but changes the prescribing decision

Epstein-Barr virus infection can cause severe exudative tonsillitis, prominent fatigue, posterior cervical lymphadenopathy and splenomegaly. Amoxicillin can cause a widespread rash in this setting, so a compatible clinical picture should prompt a review of the diagnosis and avoidance of amoxicillin.^3,4,2

The dangerous complication is spread beyond the tonsil

Peritonsillar abscess, cellulitis and deep-neck infection develop when inflammation tracks into adjacent tissue planes. Trismus, a muffled voice, uvular deviation, drooling, stridor, neck swelling or respiratory compromise should therefore trigger urgent assessment rather than simply a stronger oral antibiotic.^1,2

Presentation

Sore throat with painful swallowing, fever and inflamed tonsils, sometimes with exudate and tender anterior cervical nodes. A teenager or young adult with marked fatigue, posterior nodes or splenomegaly may have glandular fever.^1,2,3

Cardinal features

Sore throat and odynophagia
Fever or recent fever
Erythematous swollen tonsils with or without exudate
Tender anterior cervical lymphadenopathy
Cough or coryza suggesting a viral cause
Marked fatigue, posterior cervical lymphadenopathy or splenomegaly suggesting glandular fever

Red flags

Trismus, unilateral swelling, uvular deviation or a muffled voice suggesting peritonsillar abscess
Drooling, stridor, respiratory distress or inability to swallow fluids
Neck swelling or stiffness, severe systemic illness or suspected sepsis
Neurological or septic features suggesting deep-neck infection or Lemierre syndrome
Rapid deterioration or failure to improve as expected
Frequent, severe and function-limiting episodes requiring consideration of ENT referral

Investigations

Clinical assessment with FeverPAIN or Centor

Use a validated clinical score to estimate who is more likely to benefit from antibiotics, while recording hydration, airway, systemic illness, age, comorbidity and alternative diagnoses.

Expected finding: Low scores support no antibiotic; intermediate scores support no or back-up prescribing; high scores support immediate or back-up prescribing, subject to clinical context.

^1,2

Airway and deep-neck examination

Inspect the mouth and tonsils and assess voice, mouth opening, uvula, drooling, neck movement, respiratory effort and hydration. This identifies quinsy, deep-neck infection or airway compromise that a score cannot safely manage.

Expected finding: Uncomplicated disease has no airway compromise or unilateral deep-space signs; trismus, uvular deviation, drooling or stridor needs urgent escalation.

^1,2

EBV assessment when glandular fever is plausible

Consider an EBV-focused clinical assessment and appropriate serology when marked fatigue, posterior cervical lymphadenopathy, splenomegaly, atypical lymphocytosis or prolonged symptoms make glandular fever likely. Do not give amoxicillin simply because the tonsils are exudative.

Expected finding: Atypical lymphocytosis or EBV-specific serology may support infectious mononucleosis; test interpretation depends on timing and the clinical picture.

^3,4,2

Microbiology only when it will change management

Routine throat swabs or rapid pathogen testing are not required for the standard NICE antimicrobial pathway. Consider targeted testing or specialist advice for recurrent, atypical, treatment-resistant or public-health-sensitive disease.

Expected finding: No routine test is needed in a well person with typical acute sore throat and a clear clinical pathway.

^1,2

Management

Step	Detail	Source
Supportive care and safety-netting are first-line	Offer paracetamol for pain or fever, or ibuprofen if preferred and suitable, encourage adequate fluids and explain that acute sore throat including tonsillitis usually lasts about a week. Reassess if symptoms worsen rapidly or significantly, do not start to improve within a week, or the person becomes systemically very unwell.^1,2	NICE NG84, Sore throat (acute): antimicrobial prescribing
Use FeverPAIN or Centor to select the antibiotic strategy	Do not offer an antibiotic for FeverPAIN 0 or 1 or Centor 0, 1 or 2. For FeverPAIN 2 or 3, consider no antibiotic or a back-up prescription; if using back-up, advise use if symptoms do not start to improve within 3 to 5 days or worsen rapidly or significantly. For FeverPAIN 4 or 5 or Centor 3 or 4, consider an immediate or back-up antibiotic. A score never overrides airway, sepsis or alternative-diagnosis assessment.^1,2	NICE NG84 recommendations 1.1.3 and 1.1.6 to 1.1.11
Prescribe phenoxymethylpenicillin when an antibiotic is indicated	Use phenoxymethylpenicillin as first-choice oral antibiotic. For adults, NICE lists 500 mg four times a day or 1 g twice a day for 5 to 10 days; follow the current NICE age-specific table and BNF or BNFc for children, renal impairment, pregnancy and breastfeeding. A 5-day course may be enough for symptomatic cure, while 10 days may improve microbiological cure.^1,5,6	NICE NG84 antibiotic tables and BNF/BNFc
Use the correct macrolide alternative	For penicillin allergy or intolerance when the person is not pregnant, use clarithromycin according to the relevant NICE table and BNF or BNFc. If a macrolide is needed in pregnancy, erythromycin is preferred when the benefit of antibiotic treatment outweighs the potential harms.^1,7,8	NICE NG84 antibiotic tables and BNF/BNFc
Avoid amoxicillin when glandular fever is suspected	If infectious mononucleosis is a realistic differential, do not substitute amoxicillin for phenoxymethylpenicillin simply because there is tonsillar exudate. Amoxicillin can provoke a widespread maculopapular rash in glandular fever; reconsider the diagnosis, explain the likely drug reaction if it occurs and avoid incorrectly labelling the person as penicillin-allergic without appropriate assessment.^3,4,2	NHS glandular fever information, BNF amoxicillin and NICE CKS sore throat
Offer immediate antibiotics to high-risk or systemically unwell people	Offer an immediate antibiotic prescription when the person is systemically very unwell, has symptoms or signs of a more serious illness or is at high risk of complications. Give the same safety-net advice even when treatment is started, because an antibiotic does not remove airway or sepsis risk.¹	NICE NG84 recommendations 1.1.12 and 1.1.13
Refer urgently for quinsy, deep-neck infection or airway risk	Arrange same-day hospital assessment for suspected peritonsillar abscess, cellulitis, parapharyngeal or retropharyngeal abscess, Lemierre syndrome, severe systemic infection or airway compromise. Trismus, unilateral swelling, uvular deviation, drooling, stridor, inability to maintain hydration or a muffled voice should not be managed as uncomplicated tonsillitis.^1,2	NICE NG84 and NICE CKS sore throat
Consider ENT referral for recurrent disabling episodes	Discuss ENT referral for tonsillectomy assessment when recurrent episodes are adequately documented, clinically significant and disabling enough to affect normal functioning. The ENT UK/RCS commissioning guide commonly uses 7 or more documented episodes in 1 year, 5 or more per year for 2 consecutive years, or 3 or more per year for 3 consecutive years; recurrent quinsy and other individual circumstances may justify referral outside these counts. Use shared decision-making and document the burden, diagnosis and treatment of episodes.^9,10	ENT UK and Royal College of Surgeons, Commissioning guide: Tonsillectomy 2021

Illustrations

Exudative tonsillitisEnlarged tonsils with white exudate in acute exudative tonsillitis; exudate is not by itself proof of bacterial infection.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0

Centor and FeverPAIN criteriaTeaching diagram summarising FeverPAIN and Centor components and their antibiotic decision branches; thresholds are referenced to current NICE NG84.PassFinals · original

Waldeyer's ring anatomyDiagram of the palatine, lingual and pharyngeal tonsils forming Waldeyer's ring at the entrance to the pharynx.PassFinals · original

Differentials

Viral pharyngitis

Cough, coryza, conjunctivitis or a low FeverPAIN/Centor score.

Glandular fever

Marked fatigue, posterior cervical lymphadenopathy, splenomegaly or prolonged illness.

Peritonsillar abscess (quinsy)

Unilateral severe pain, trismus, uvular deviation and a muffled voice.

Epiglottitis or other airway emergency

Drooling, stridor, respiratory distress or toxic appearance with little visible tonsillar explanation.

Scarlet fever or diphtheria

Rash or an adherent pseudomembrane in the appropriate clinical and vaccination context.

Complications

Peritonsillar abscess and cellulitis
Parapharyngeal or retropharyngeal abscess
Lemierre syndrome and sepsis
Airway compromise
Rare post-streptococcal immune complications
Recurrent disabling tonsillitis with impact on normal functioning

Prognosis

Most people improve within approximately a week without antibiotics. Targeted antibiotics modestly shorten symptoms in people more likely to have streptococcal disease, while quinsy, deep-neck infection, airway compromise and sepsis are uncommon but require urgent escalation. Recurrent disabling episodes may lead to ENT shared decision-making about tonsillectomy.

Guidelines

Sore throat (acute): antimicrobial prescribing (NG84) (NICE, 2018)
Sore throat acute (NICE CKS) (NICE, 2023)
Commissioning guide: Tonsillectomy (ENT UK and Royal College of Surgeons, 2021)

References

Evidence checked: 2026-08-03

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.