What is the likely cause of the patient’s symptoms?

A summary of causes of sore throat is provided in Causes of sore throat.

Note: Viral pharyngitis and tonsillitis are the most common causes of sore throat.

Viral pharyngitis and tonsillitis are the most common causes of sore throat in patients of all ages; these infections are self-limiting and symptoms usually resolve within 7 days.

Bacterial infection is a less common cause of sore throat; Streptococcus pyogenes (group A streptococcus) is the most frequently implicated bacterial pathogen and is more common in children than in adultsOliver, 2018 Pearce, 2020 RHDAustralia (ARF/RHD writing group), 2020. Streptococcal pharyngitis and tonsillitis are usually self-limiting with symptoms lasting 7 days, but some patient groups are at higher risk of developing acute rheumatic fever, particularly following recurrent streptococcal throat infections. For patient groups at high risk of acute rheumatic fever, see Determining risk of acute rheumatic fever in patients with pharyngitis and tonsillitis.

Other nonsuppurative complications of S. pyogenes pharyngitis and tonsillitis include acute poststreptococcal glomerulonephritis and scarlet fever. Acute poststreptococcal glomerulonephritis can occur following infection with specific nephritogenic strains of S. pyogenes. For more information on scarlet fever, see Role of clinical features in distinguishing between viral and streptococcal pharyngitis and tonsillitis.

Distinguishing between viral and streptococcal pharyngitis and tonsillitis can be challenging; see Role of clinical features in distinguishing between viral and streptococcal pharyngitis and tonsillitis and Role of investigations in viral and streptococcal pharyngitis and tonsillitis for further discussion. Therefore, for patients at high risk of acute rheumatic fever (see Determining risk of acute rheumatic fever in patients with pharyngitis and tonsillitis), empirical antibiotic therapy for streptococcal infection is recommended for the primary prevention of acute rheumatic fever, regardless of the patient’s clinical features (see Approach to managing pharyngitis and tonsillitis in patients at high risk of acute rheumatic fever). For patients not at high risk of acute rheumatic fever, distinguishing between viral and streptococcal pharyngitis and tonsillitis can change management, but even if streptococcal infection is likely, empirical antibiotic therapy is not required for most patients (see Approach to managing pharyngitis and tonsillitis in patients not at high risk of acute rheumatic fever).

Table 1. Causes of sore throat
conditions associated with airway obstruction or deep neck space infection viral pharyngitis and tonsillitis Streptococcus pyogenes (group A streptococcus) pharyngitis and tonsillitis Epstein–Barr virus (EBV) infection primary oral mucocutaneous herpes hand, foot and mouth disease herpangina sexually transmitted infections Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum) pharyngitis and tonsillitis other rarer bacterial causes noninfective causes
Condition	Details
conditions associated with airway obstruction or deep neck space infection	acute epiglottitis peritonsillar abscess and peritonsillar cellulitis retropharyngeal abscess parapharyngeal abscess pharyngeal diphtheria severe Epstein–Barr virus (EBV) infection severe croup or bacterial tracheitis spreading odontogenic infections (including Ludwig angina) septic jugular thrombophlebitis (Lemierre syndrome) For clinical features associated with airway obstruction or deep neck space infection, see Clinical features associated with airway obstruction or deep neck space infection. Urgent transfer to hospital and airway management is required.
viral pharyngitis and tonsillitis	Most common cause of sore throat in patients of all ages. Common respiratory viruses include respiratory syncytial virus, rhinovirus, adenovirus, influenza virus and parainfluenza virusShulman, 2012. Clinical features include cough, hoarse voice, conjunctivitis, nasal congestion, anterior stomatitis, viral exanthema and diarrhoeaShulman, 2012. For advice on when to test for respiratory viruses, see Role of investigations in viral and streptococcal pharyngitis and tonsillitis. Sore throat can be a presenting feature of coronavirus disease (COVID-19); refer to state and territory health department guidelines for advice on testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and management of COVID-19.
Streptococcus pyogenes (group A streptococcus) pharyngitis and tonsillitis (streptococcal pharyngitis and tonsillitis)	More common in school-aged children and adolescents, but can occur in younger children and adults. Clinical features include abrupt onset of symptoms, fever (above 38°C), tender cervical lymphadenopathy, tonsillar exudate, and the absence of cough, rhinorrhoea or nasal congestionShulman, 2012. S. pyogenes pharyngitis can present with the classic rash of scarlet fever; see Role of clinical features in distinguishing between viral and streptococcal pharyngitis and tonsillitis for more information. For advice on when to test for S. pyogenes infection, see Role of investigations in viral and streptococcal pharyngitis and tonsillitis.
Epstein–Barr virus (EBV) infection (glandular fever, infectious mononucleosis)	Common in adolescents and young adults. Clinical features include severe sore throat, fever, nausea, lymphadenopathy, splenomegaly, hepatomegaly, rash and fatigue. If suspected, consider performing an infectious mononucleosis (IM) test or EBV serology.
primary oral mucocutaneous herpes (herpes gingivostomatitis)	More common in children younger than 5 years, but can occur in older children and adolescents. Clinical features include fever, intraoral or hypopharyngeal lesions, aphthous tonsil ulcers and cervical lymphadenopathy. If suspected, consider collecting a throat swab for herpes simplex virus (HSV) type–specific nucleic acid amplification testing (eg polymerase chain reaction [PCR]).
hand, foot and mouth disease	Common in children. Usually caused by coxsackieviruses. Clinical features include vesicular or ulcerative mucosal eruptions in the mouth and throat, loss of appetite, and rash or skin lesions.
herpangina	Common in children. Usually caused by coxsackieviruses. Clinical features include high fever (above 38.5°C), vesicular or ulcerative mucosal eruptions in the mouth and throat, cervical lymphadenopathy, headache, abdominal pain, vomiting and loss of appetite.
sexually transmitted infections: Neisseria gonorrhoeae infection Early syphilis	Occur in sexually active patients. These infections are usually asymptomatic, but patients can present with pharyngeal symptoms.
Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum) pharyngitis and tonsillitis	An uncommon cause of pharyngitis and tonsillitis; more common in patients aged 10 to 24 years. Clinical features are similar to streptococcal pharyngitis and tonsillitis. Consider diagnosis in patients who do not respond to empirical antibiotic therapy for streptococcal infection. A rash, similar to scarlet fever, may occur and can be misattributed to penicillin hypersensitivity. Can be identified on throat swab culture; request laboratory to specifically look for this organism to increase the yield.
other rarer bacterial causes Shulman, 2012	Group C and G streptococci (management is generally the same as for S. pyogenes pharyngitis and tonsillitis; if uncertain, seek expert advice), Corynebacterium diphtheriae (see Pharyngeal diphtheria), mixed infections with anaerobic bacteria, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Fusobacterium necrophorum
noninfective causes	Trauma, gastro-oesophageal reflux, postnasal drip due to allergic rhinitis and rhinosinusitis, house dust mite allergy, cigarette smoke, dry air, snoring, tracheal intubation, malignancy and medicationsRenner, 2012.