Sore throat

Sore throat is pain, scratchiness or irritation of the pharynx, worse on swallowing. Most cases are viral and self limiting.

Clinical relevance. Acute sore throat is among the commonest reasons for consultation. Streptococcal pharyngitis accounts for about 5 to 15 percent of adult cases and about 20 to 30 percent of cases in children.

Complications:

• suppurative: peritonsillar abscess, parapharyngeal and retropharyngeal abscess, cervical lymphadenitis
• non-suppurative: acute rheumatic fever, post-streptococcal glomerulonephritis

Mechanisms. Mucosal inflammation from infection, irritation (reflux, smoke, dry air, postnasal drip), allergy, or mass lesions.

Classification. Acute (under 2 weeks), prolonged (2 to 4 weeks) and chronic (over 4 weeks); recurrent (repeated discrete episodes). By anatomy: pharyngitis, tonsillitis, laryngitis and supraglottitis.

Scoring.

• Centor criteria score one point each for tonsillar exudate, tender anterior cervical nodes, fever over 38 degrees Celsius, and absence of cough. Add one for age 3 to 14 years and subtract one for age 45 or over.
• FeverPAIN scores one point each for fever in the last 24 hours, purulence, attendance within 3 days of onset, severely inflamed tonsils, and no cough or coryza.

A Centor score of 3 or 4, or a FeverPAIN score of 4 or 5, supports bacterial infection. The predictive value is modest (positive predictive value about 40 to 60 percent).

History. Duration, severity, fever, odynophagia, ability to swallow saliva and fluids, drooling, voice change (muffled voice, hot potato voice), trismus, neck swelling or stiffness, ear pain, cough, coryza, hoarseness, rash, joint pain.

Also ask about contacts with streptococcal infection, vaccination status (diphtheria), oral sex and sexual history (gonorrhoea), HIV risk, immunosuppression, smoking and alcohol, weight loss, and previous episodes.

Drug history. Carbimazole, methimazole and other antithyroid drugs, clozapine, sulphasalazine, deferiprone and other drugs causing agranulocytosis; inhaled corticosteroids (candidiasis); chemotherapy.

Examination. Temperature, pulse, respiratory rate, oxygen saturation, hydration, drooling, stridor, voice quality, trismus. Then:

• oropharynx: tonsil size and symmetry, exudate, erythema, uvular deviation, palatal petechiae, vesicles, ulcers, grey membrane, white plaques
• neck: tender cervical nodes, swelling, stiffness, torticollis
• rash (scarlatiniform), hepatosplenomegaly, and chest

Red flags

• Stridor, drooling, inability to swallow saliva, tripod posture, or muffled voice (epiglottitis, airway obstruction)
• Trismus with unilateral tonsillar swelling and uvular deviation (peritonsillar abscess)
• Neck swelling, stiffness or torticollis, or pain on neck movement (parapharyngeal or retropharyngeal abscess)
• Fever, neutropenia, or mouth ulcers with a culprit drug (agranulocytosis)
• Grey adherent pseudomembrane with bull neck (diphtheria)
• Severe unilateral pain with otalgia and weight loss, or persistent unilateral tonsil enlargement or ulcer (cancer)
• Sore throat with rash, jaundice, hepatosplenomegaly or lymphadenopathy (infectious mononucleosis, HIV seroconversion)
• Immunosuppression or diabetes
• Sore throat lasting over 3 weeks

Special groups.

• Children: diphtheria, scarlet fever and streptococcal infection are more frequent; avoid aspirin (Reye syndrome).
• Pregnancy: use penicillin; avoid tetracyclines.
• Region specific: diphtheria occurs where immunisation is incomplete, and rheumatic fever remains common where access to care is limited.

Infective, acute

• Viral pharyngitis (rhinovirus, coronavirus, adenovirus, influenza, parainfluenza, respiratory syncytial virus, COVID-19)
• Group A streptococcal pharyngitis and tonsillitis, scarlet fever; groups C and G streptococci
• Infectious mononucleosis (Epstein Barr virus), cytomegalovirus, acute HIV infection
• Herpangina and hand foot and mouth disease (coxsackievirus), herpes simplex gingivostomatitis
• Gonococcal pharyngitis, Fusobacterium necrophorum infection (Lemierre syndrome), Arcanobacterium haemolyticum, Mycoplasma pneumoniae
• Diphtheria, syphilis (secondary), tuberculosis
• Candidiasis (oropharyngeal)

Suppurative and airway threatening

• Peritonsillar abscess (quinsy), parapharyngeal abscess, retropharyngeal abscess
• Epiglottitis and supraglottitis, bacterial tracheitis, Ludwig angina
• Lemierre syndrome (internal jugular vein thrombophlebitis)

Non-infective

• Gastro-oesophageal and laryngopharyngeal reflux
• Allergic rhinitis and postnasal drip, mouth breathing, dry air
• Smoking, alcohol, irritants, vocal strain
• Agranulocytosis and neutropenia, aphthous ulcers
• Kawasaki disease, Behcet disease, periodic fever syndromes (PFAPA), adult onset Still disease
• Thyroiditis (subacute), Eagle syndrome
• Foreign body (fish bone)

Neoplastic

• Tonsil carcinoma, oropharyngeal and hypopharyngeal carcinoma, nasopharyngeal carcinoma, lymphoma, leukaemia

Reasoning. Exclude airway threats and deep neck infection first. Then score for streptococcal infection, test where it changes management, and decide on investigation for persistent, unilateral or recurrent symptoms.

First line. Vital signs, oxygen saturation, oropharyngeal and neck examination, Centor or FeverPAIN score.

Targeted tests.

• Rapid antigen detection test or throat swab culture for streptococci when Centor is 3 or more or FeverPAIN is 4 or more. Rapid antigen tests have specificity over 95 percent and sensitivity of about 85 to 90 percent. Culture confirms negative rapid tests in children.
• Full blood count and film (atypical lymphocytes in mononucleosis, neutropenia), monospot or Epstein Barr virus serology, liver function (transaminases rise in mononucleosis).
• HIV antigen and antibody test and viral load in suspected acute HIV infection. Syphilis serology.
• Nucleic acid amplification test from throat swab for gonorrhoea and chlamydia when sexual exposure.
• Throat swab for Corynebacterium diphtheriae culture and toxin testing (notify public health) when a membrane is present.
• Contrast CT neck for suspected abscess (peritonsillar, parapharyngeal, retropharyngeal) or Lemierre syndrome (with venography). Lateral neck radiograph is less useful.
• Flexible nasopharyngolaryngoscopy for persistent or unilateral symptoms, stridor, voice change or suspected supraglottitis (only with airway expertise available).
• Biopsy and staging for any suspicious ulcer or mass (CT neck and chest, MRI).
• Urinalysis and antistreptolysin O in suspected complications of streptococcal infection.

Limitations. Scores do not replace testing. Carriage of streptococci confounds a positive test. Throat cultures take 24 to 48 hours.

Airway emergencies. Epiglottitis, supraglottitis or airway obstruction:

• do not examine the throat with a spatula in children
• keep the patient upright and calm, and give oxygen
• call anaesthetic, ENT and senior help at once, and secure the airway in theatre
• after airway control, ceftriaxone 2 g IV daily (children 50 to 80 mg/kg daily, maximum 2 g), with dexamethasone 10 mg IV (children 0.15 mg/kg) in selected cases

Analgesia (all patients).

• Paracetamol 1 g orally every 4 to 6 hours (maximum 4 g in 24 hours; 2 g in 24 hours with weight under 50 kg, chronic alcohol use or liver disease; children 15 mg/kg every 4 to 6 hours, maximum 60 mg/kg in 24 hours).
• Ibuprofen 400 mg orally every 6 to 8 hours with food (maximum 2.4 g in 24 hours; children over 3 months 5 to 10 mg/kg every 6 to 8 hours, maximum 30 mg/kg in 24 hours). Avoid it in renal impairment, heart failure, peptic ulcer and the third trimester.
• Benzydamine 0.15 percent oral rinse or spray, 15 mL rinse every 1.5 to 3 hours for up to 7 days, or lidocaine lozenges, for short term relief.
• Hydration and rest.
• Dexamethasone 10 mg orally or IV as a single dose reduces pain in severe sore throat. The evidence is modest; avoid in diabetes or active infection that is not controlled.

Viral pharyngitis. No antibiotics. Review in 5 to 7 days if not improving.

Group A streptococcal infection. Treat when the test is positive or in high risk patients (history of rheumatic fever, immunosuppression, scarlet fever, outbreaks):

• Phenoxymethylpenicillin 500 mg orally four times daily (or 1 g twice daily) for 10 days (children 250 mg two to four times daily by age, for 10 days).
• Benzathine benzylpenicillin 1.2 million units IM as a single dose (600,000 units for weight under 27 kg) when adherence is doubtful.
• Penicillin allergy (non-severe): cefalexin 500 mg orally twice daily for 10 days.
• Severe allergy: azithromycin 500 mg orally on day 1 then 250 mg daily for 4 days, or clarithromycin 250 to 500 mg orally twice daily for 5 days (halve when creatinine clearance is under 30 mL/min; interactions via CYP3A4).
• Return to school or work after 24 hours of antibiotics.

Infectious mononucleosis.

• Supportive care; avoid amoxicillin and ampicillin (rash).
• Avoid contact sports and heavy lifting for at least 4 weeks and until splenomegaly resolves (risk of splenic rupture).
• Prednisolone 40 to 60 mg orally daily for 3 to 5 days for airway compromise or severe tonsillar swelling.
• Test for HIV in adults.

Peritonsillar abscess. Needle aspiration or incision and drainage by ENT the same day. Give benzylpenicillin 1.2 g IV every 6 hours (children 50 mg/kg every 6 hours, maximum 1.2 g) plus metronidazole 500 mg IV every 8 hours. Then switch to oral phenoxymethylpenicillin 500 mg four times daily with metronidazole 400 mg three times daily to complete 7 to 10 days. Penicillin allergy: clindamycin 600 mg IV every 8 hours then 300 to 450 mg orally four times daily. Tonsillectomy is considered after recurrent abscess.

Parapharyngeal and retropharyngeal abscess, Ludwig angina, Lemierre syndrome.

• Admit; airway assessment.
• Ceftriaxone 2 g IV every 24 hours (children 50 to 80 mg/kg, maximum 2 g) plus metronidazole 500 mg IV every 8 hours (or piperacillin with tazobactam 4.5 g IV every 6 to 8 hours).
• Urgent surgical drainage by ENT.
• Anticoagulation for Lemierre syndrome by specialist decision (enoxaparin 1 mg/kg subcutaneously every 12 hours, adjusted when creatinine clearance is under 30 mL/min).

Gonococcal pharyngitis. Ceftriaxone 1 g IM as a single dose, with test of cure at 2 weeks, partner notification and screening for other infections. Add doxycycline 100 mg orally twice daily for 7 days when chlamydia is not excluded.

Candidiasis. Nystatin 100,000 units/mL, 1 mL held in the mouth then swallowed four times daily for 7 to 14 days, or fluconazole 50 to 100 mg orally once daily for 7 to 14 days (adjust in renal impairment; interactions with warfarin and statins). Rinse the mouth and review inhaler technique with inhaled corticosteroids.

Diphtheria. Immediate admission with isolation. Give diphtheria antitoxin 20,000 to 100,000 units IV (by severity, after sensitivity testing) and benzylpenicillin or erythromycin for 14 days. Cardiac monitoring, airway support, public health notification and contact prophylaxis.

Agranulocytosis. Stop the culprit drug, admit with neutropenic precautions, and start piperacillin with tazobactam 4.5 g IV every 6 hours when febrile. Haematology review; filgrastim 5 micrograms/kg subcutaneously daily by specialist.

Reflux. Omeprazole 20 to 40 mg orally once daily before breakfast for 8 weeks, alginate after meals, and lifestyle measures.

Neoplasm. Urgent head and neck oncology referral with biopsy and staging.

Recurrent tonsillitis. Tonsillectomy is considered for 7 or more well documented episodes in 1 year, 5 or more each year in 2 years, or 3 or more each year in 3 years, with each episode disabling and treated.

Monitoring. Review in 48 to 72 hours if severe or not improving. For streptococcal infection, advise on rheumatic fever symptoms (joint pain, rash, chorea, carditis) and post-streptococcal glomerulonephritis (cola coloured urine, oedema, hypertension) over the following weeks.

Referral and escalation. Immediate for airway compromise, suspected epiglottitis, deep neck abscess, diphtheria or agranulocytosis. ENT same day for peritonsillar abscess. ENT within 2 weeks for persistent unilateral symptoms, ulcer, mass or sore throat over 3 weeks.

Admission criteria. Airway compromise, inability to swallow fluids, abscess, neutropenic fever, diphtheria, systemic toxicity, or immunosuppression with severe infection.

Discharge and safety netting. Return for drooling, difficulty breathing, noisy breathing, inability to swallow fluids, neck swelling or stiffness, trismus, high fever, rash, dark urine, joint pain, or symptoms over 1 week without improvement.