Tonsillitis — Symptoms, Causes & Treatment | MyMedicPlus

Tonsillitis is inflammation of the palatine tonsils — the paired lymphoid organs at the back of the throat that form part of Waldeyer's tonsillar ring and serve as a first line of immunological defence against inhaled and ingested pathogens. It is one of the most common conditions presenting to primary care, particularly in children aged 5-15 years. Tonsillitis is most commonly caused by respiratory viruses (adenovirus, Epstein-Barr virus, rhinovirus, influenza, parainfluenza) across all age groups, accounting for approximately 70-85% of cases. Bacterial causes — principally Group A beta-haemolytic Streptococcus (GABHS, Streptococcus pyogenes) — account for 15-30% of cases in children and 5-15% in adults, but are clinically critical to identify because: untreated GABHS tonsillitis carries the risk of acute rheumatic fever (causing permanent cardiac valve damage) and post-streptococcal glomerulonephritis; antibiotics reduce the duration and severity of symptoms; and GABHS is highly contagious (spread by respiratory droplets in schools and households). Viral tonsillitis is self-limiting (resolving in 5-7 days without antibiotics). Tonsillitis is distinct from pharyngitis (inflammation of the pharyngeal mucosa), though both frequently coexist as 'pharyngotonsillitis.' Recurrent tonsillitis (meeting the Paradise criteria) is a common indication for tonsillectomy in children and adults.

Viral causes (70-85% of all tonsillitis): adenovirus (the single most common viral cause — presents with prominent pharyngitis, exudate, and conjunctivitis — 'pharyngoconjunctival fever'); rhinovirus; Epstein-Barr virus (EBV — causes infectious mononucleosis/glandular fever — important to identify because: severe prolonged illness, amoxicillin causes florid maculopapular rash, contact sports must be avoided due to splenomegaly and splenic rupture risk); influenza A and B; parainfluenza; coxsackievirus and enteroviruses (herpes angina — vesicles and ulcers on tonsils and soft palate). Bacterial causes (15-30%): Group A beta-haemolytic Streptococcus (GABHS — Streptococcus pyogenes) is by far the most important; distinguished from viral by: sudden onset, fever above 38°C, tonsillar exudate, anterior cervical lymphadenopathy, and absence of cough (Centor criteria); Fusobacterium necrophorum (an increasingly recognised cause of tonsillitis and peritonsillar abscess in adolescents — associated risk of the serious Lemierre's syndrome). Risk factors: age 5-15 years (highest incidence of GABHS tonsillitis); attendance at school or nursery (close contact facilitates droplet transmission); military barracks and dormitory settings; winter months (peak season for both viral and GABHS tonsillitis); immunosuppression; and prior tonsillitis (recurrent susceptibility).

Tonsillitis typically presents with: sore throat — the cardinal symptom, ranging from mild discomfort to severe pain preventing swallowing; odynophagia (painful swallowing — the severity of pain on swallowing is an important indicator of GABHS tonsillitis and peritonsillar abscess formation); tonsillar erythema (redness and enlargement of the palatine tonsils — may be graded I-IV based on size relative to the oropharynx); tonsillar exudate (white, yellow, or grey patches or confluent coating on the tonsillar surface — present in both GABHS and EBV but not in viral tonsillitis from rhinovirus or adenovirus without exudate); anterior cervical lymphadenopathy (tender, enlarged lymph nodes under the angle of the jaw — most characteristic of GABHS tonsillitis); fever above 38 degrees Celsius — present in GABHS and EBV, less common in purely viral tonsillitis; and fetid breath (halitosis) from tonsillar debris and exudate. GABHS-specific features: sudden onset; high fever (38-40 degrees); severe pain; exudate; tender cervical nodes; absence of cough, runny nose, or hoarseness (these suggest viral aetiology and argue against GABHS). Epstein-Barr virus (EBV — glandular fever): particularly severe and prolonged course (2-3 weeks); profound fatigue; generalised lymphadenopathy (including posterior cervical and axillary nodes); hepatosplenomegaly (spleen enlargement — requires sport restriction due to rupture risk); maculopapular rash (erythematous skin rash) occurring spontaneously in some patients and universally after amoxicillin or ampicillin — the EBV-amoxicillin rash is a drug hypersensitivity reaction, not true penicillin allergy. Peritonsillar abscess (quinsy): unilateral throat pain disproportionately severe; trismus (jaw stiffness — painful mouth opening); hot-potato voice (muffled, potato-in-mouth quality of speech); uvular deviation toward the unaffected side.

Clinical scoring systems guide the probability of GABHS and the need for antibiotic testing. Centor score (4 criteria): tonsillar exudate; tender anterior cervical lymphadenopathy; history of fever; absence of cough — each criterion scores 1 point; total 4 points = 56% probability of GABHS; 0-1 points = antibiotic unlikely beneficial; 2-3 points = throat swab or RADT recommended; 4 points = treat or test-and-treat. FeverPAIN score (validated in UK primary care, 5 criteria): Fever; Purulence; Attended rapidly (within 3 days); severely Inflamed tonsils; No cough/coryza — score 4-5 = 65% GABHS probability; immediate antibiotic treatment or RADT recommended. Rapid antigen detection test (RADT) for Group A Streptococcus: lateral flow immunoassay from throat swab result within 5-15 minutes; sensitivity 70-90%, specificity above 95% — a positive result warrants antibiotic treatment; a negative result in a high-probability clinical presentation may require confirmation with throat culture. Throat swab culture (gold standard): 24-48 hour turnaround; 90-95% sensitivity for GABHS — reserves for RADT-negative high-clinical-probability cases or recurrent/treatment-failure cases. EBV serology: monospot (heterophile antibody) test — positive in 85% of EBV by week 2 (false-negative in young children and early infection); EBV-specific serology (VCA IgM — viral capsid antigen) is more sensitive. Full blood count (FBC): lymphocytosis with atypical lymphocytes (Downey cells) on blood film strongly suggests EBV. Throat abscess assessment: flexible nasendoscopy or lateral neck ultrasound to assess for peritonsillar or parapharyngeal abscess.

Viral tonsillitis (majority of cases): entirely supportive — regular analgesia (paracetamol 1 g four times daily or ibuprofen 400 mg three times daily with food; both reduce fever and throat pain); soluble aspirin gargle (adults only — analgesic effect on tonsillar mucosa); throat lozenges (benzydamine, flurbiprofen — local anti-inflammatory effect); adequate oral fluid intake to prevent dehydration; and rest. Antibiotics are not indicated and do not shorten viral illness. GABHS tonsillitis: phenoxymethylpenicillin (penicillin V) 500 mg four times daily for 10 days — first-line antibiotic; reduces symptom duration by 1-2 days, prevents suppurative complications, and critically eliminates the risk of rheumatic fever. Amoxicillin should be avoided where EBV cannot be excluded — in confirmed GABHS without EBV suspicion, amoxicillin 500 mg three times daily for 10 days is acceptable. Azithromycin 500 mg daily for 5 days or clarithromycin 250 mg twice daily for 5 days in confirmed penicillin allergy (erythromycin resistance above 10% in GABHS). Glandular fever (EBV): supportive care; avoid amoxicillin and ampicillin; advise contact sports and vigorous exercise avoidance for 3-4 weeks due to splenomegaly and splenic rupture risk; corticosteroids (prednisolone 40 mg for 5 days) for severe airway compromise from tonsillar hypertrophy. Peritonsillar abscess: ENT referral for needle aspiration or incision and drainage under local anaesthesia; oral antibiotics (co-amoxiclav 625 mg three times daily for 5-7 days); intravenous antibiotics and surgical drainage for large or bilateral abscess. Tonsillectomy: recommended for recurrent tonsillitis meeting Paradise criteria (7 or more episodes in 1 year; 5 or more per year for 2 consecutive years; 3 or more per year for 3 consecutive years — each documented episode with clinical features). Also indicated for tonsillar hypertrophy causing obstructive sleep apnoea or difficulty eating.

Peritonsillar abscess (quinsy): the most common complication of GABHS tonsillitis, occurring in 1-3% of cases — a collection of pus in the peritonsillar space between the tonsil capsule and the superior constrictor muscle; presents with unilateral severe throat pain, trismus, uvular deviation, hot-potato voice, and drooling; requires ENT-led drainage and intravenous antibiotics. Parapharyngeal or retropharyngeal abscess: deep neck space infections requiring CT neck for diagnosis and surgical drainage; can cause airway compromise. Lemierre's syndrome: rare but life-threatening complication caused by Fusobacterium necrophorum tonsillitis in adolescents and young adults — septic thrombophlebitis of the internal jugular vein with secondary haematogenous spread (lung abscesses, septic arthritis, meningitis); requires prolonged intravenous antibiotics (metronidazole plus beta-lactam) and anticoagulation. Rheumatic fever: non-suppurative complication of untreated GABHS tonsillitis occurring 2-3 weeks after the infection — acute rheumatic fever causes migratory arthritis, carditis (mitral and aortic valve inflammation leading to permanent scarring and valvular disease), Sydenham's chorea, and subcutaneous nodules; prevented by completing a full course of penicillin. Post-streptococcal glomerulonephritis: immune-mediated glomerular damage presenting 10-21 days after GABHS tonsillitis with haematuria, proteinuria, and hypertension. Obstructive sleep apnoea from chronic tonsillar hypertrophy — particularly in children — is a principal indication for tonsillectomy.

Hand hygiene is the most effective measure for preventing transmission of both viral and bacterial tonsillitis — wash hands thoroughly after contact with a symptomatic individual, and avoid touching the face. Avoid sharing cups, utensils, water bottles, or eating from the same food as someone with tonsillitis during the infectious period. Replace your toothbrush immediately after completing antibiotic treatment for GABHS tonsillitis — toothbrushes harbour bacteria and reinfection is possible from an unchanged brush. Complete the full antibiotic course (10 days of penicillin V) — stopping antibiotics early when symptoms improve is a major risk factor for treatment failure, rheumatic fever, and the development of antibiotic resistance. For children and adults with recurrent documented tonsillitis, referral to ENT for tonsillectomy consideration is appropriate when Paradise criteria are met — tonsillectomy reduces subsequent tonsillitis episodes by approximately 90% in the 2 years following surgery and eliminates the ongoing risk of peritonsillar abscess and rheumatic fever. In high-rheumatic-fever-risk regions (Sub-Saharan Africa, South Asia), prophylactic long-acting penicillin G benzathine injection every 3-4 weeks may be recommended to prevent rheumatic recurrence in patients with established rheumatic heart disease.

See your GP if tonsillitis symptoms are severe or not improving after 3–4 days, particularly in a child; if you cannot swallow fluids (risk of dehydration); or if you develop a severe headache with neck stiffness and photophobia (possible meningitis). A throat swab or rapid antigen test can confirm Group A Streptococcus and guide antibiotic prescribing. Seek emergency assessment for: drooling and inability to swallow (quinsy or epiglottitis — medical emergency); stridor (high-pitched inspiratory noise from airway obstruction); rapidly worsening neck swelling (parapharyngeal or retropharyngeal abscess — spreading infection requiring surgical drainage); and severe trismus (inability to open the mouth) with asymmetric soft palate bulging (peritonsillar abscess — urgent ENT referral for aspiration or incision and drainage). Recurrent tonsillitis meeting the Paradise criteria (7 or more episodes in 1 year, 5 or more per year for 2 years, or 3 or more per year for 3 years) should be referred to an ENT surgeon for consideration of tonsillectomy.