Key Facts

Tonsillitis is an acute inflammatory condition of the palatine tonsils, usually caused by viral or bacterial infection. It is one of the most common reasons for GP consultation and antibiotic prescribing, making appropriate use of clinical scoring systems essential to reduce unnecessary antibiotic use.

Epidemiology

• Extremely common, particularly in children aged 5-15 years
• Less common in adults >40 and children <3
• Most cases are viral (70-80%)
• Peak incidence: winter and early spring
• Recurrent tonsillitis affects approximately 11% of children

Aetiology

• Viral (most common): EBV (glandular fever), adenovirus, rhinovirus, influenza, parainfluenza, enterovirus, coronavirus
• Bacterial: Group A Streptococcus (GAS/Streptococcus pyogenes) — 15-30% in children, 5-10% in adults
• Other bacteria: Group C/G Streptococcus, Fusobacterium necrophorum (Lemierre syndrome), Arcanobacterium haemolyticum

Pathophysiology

• Pharyngeal lymphoid tissue (Waldeyer's ring) is exposed to inhaled/ingested pathogens
• Tonsils are immunologically active, particularly in childhood, trapping and processing antigens
• Infection triggers acute inflammatory response: neutrophil infiltration, oedema, exudate
• Recurrent infections may lead to tonsillar hypertrophy and cryptic debris accumulation
• GAS produces virulence factors: M protein (adhesion, immune evasion), streptolysin O/S (tissue damage), pyrogenic exotoxins (scarlet fever)

Typical Presentation

• Sore throat (odynophagia): often severe, difficulty swallowing
• Fever (>38°C)
• Tonsillar enlargement and erythema ± exudate (white/yellow spots or membrane)
• Tender cervical lymphadenopathy (anterior chain)
• Malaise, headache
• Children: may present with abdominal pain, nausea

Viral vs Bacterial Features

• Viral: concurrent coryza, cough, conjunctivitis, hoarseness, diarrhoea
• Bacterial (GAS): acute onset, high fever, exudate, tender anterior lymph nodes, absence of cough/coryza, scarlatiniform rash (scarlet fever)

Red Flags

• Unilateral tonsillar swelling with trismus (peritonsillar abscess/quinsy)
• Drooling, muffled voice ('hot potato'), neck stiffness (parapharyngeal/retropharyngeal abscess)
• Stridor or respiratory distress (airway compromise)
• Inability to swallow fluids (severe dehydration risk)
• Persistent fever >5 days despite antibiotics (abscess, EBV, alternative diagnosis)
• Sandpaper rash (scarlet fever — notifiable disease)

Bedside

• Clinical assessment using FeverPAIN score or Centor criteria
• Throat examination: tonsillar size, erythema, exudate, asymmetry
• Temperature
• Assessment for dehydration

Bloods

• Not routinely required for uncomplicated tonsillitis
• FBC: if EBV suspected (atypical lymphocytes >20%)
• Monospot/Paul-Bunnell test: heterophile antibodies for EBV (sensitivity ~85% in second week; may be negative initially)
• EBV serology: IgM VCA (acute infection)
• LFTs: often deranged in EBV
• ASO titre/anti-DNase B: if post-streptococcal complications suspected (retrospective)

Microbiology

• Throat swab: not routinely recommended in primary care (NICE NG84) — delay in results; treat based on clinical scoring
• Rapid antigen detection test (RADT) for GAS: not widely used in UK primary care

Imaging

• Not required for uncomplicated tonsillitis
• CT neck with contrast: if peritonsillar/parapharyngeal/retropharyngeal abscess suspected

Non-pharmacological

• Adequate fluid intake
• Soft diet
• Rest
• Avoid smoking

Pharmacological

• Analgesia (mainstay for all cases): paracetamol 1g QDS and/or ibuprofen 400mg TDS
• Antibiotic prescribing (NICE NG84 — FeverPAIN score):
  • Score 0-1: no antibiotic (self-limiting viral illness >80% probability)
  • Score 2-3: delayed (back-up) prescription to use if not improving at 3-5 days
  • Score 4-5: immediate antibiotic prescription
• First-line: phenoxymethylpenicillin (penicillin V) 500mg QDS (adults) or 250mg QDS (children) for 5-10 days
• Penicillin allergy: clarithromycin 500mg BD for 5 days
• Severe/unable to swallow: IM benzylpenicillin 1.2g stat or IV amoxicillin
• AVOID amoxicillin if EBV suspected (maculopapular rash in >90%)
• Corticosteroids: single dose dexamethasone 10mg PO or IM may reduce pain severity and duration (TOAST trial); not routinely recommended in NICE

Surgical

• Tonsillectomy indications (Paradise criteria/SIGN 117):
  • ≥7 episodes in 1 year, OR
  • ≥5 episodes per year for 2 years, OR
  • ≥3 episodes per year for 3 years
  • Each episode should be documented as: sore throat + one of: fever >38.3°C, cervical lymphadenopathy, tonsillar exudate, positive GAS culture
• Also indicated for peritonsillar abscess (quinsy tonsillectomy or interval tonsillectomy)

Referral Criteria

• ENT referral: meets tonsillectomy criteria, recurrent peritonsillar abscess, suspected malignancy (unilateral enlargement in adult)
• Emergency referral: suspected quinsy, airway compromise, parapharyngeal abscess, Lemierre syndrome
• Hospital admission: unable to swallow fluids, signs of sepsis, respiratory compromise

• Most cases resolve within 7-10 days regardless of antibiotic treatment
• Antibiotics reduce symptom duration by approximately 1 day (NNT 6 for sore throat at day 3)
• Peritonsillar abscess complicates 1-3% of untreated bacterial tonsillitis
• Rheumatic fever: rare in UK but important globally (follows GAS pharyngitis by 2-4 weeks)
• Post-streptococcal glomerulonephritis: 1-3 weeks after GAS; antibiotics do NOT prevent this
• Tonsillectomy reduces episodes of sore throat for 1-2 years but benefit may diminish over time
• Post-tonsillectomy haemorrhage: primary (<24h) 0.5-2%, secondary (5-10 days) 2-4%

FeverPAIN Score (NICE NG84)

Centor Criteria (Modified)

Complications of GAS Tonsillitis