Sore throat

What is a sore throat?

Sore throat is a symptom resulting from inflammation of the upper respiratory tract. Four regions are principally involved - the pharynx, the larynx, the tonsils and (rarely) the epiglottis.

How common are sore throats? (Epidemiology)

Sore throat is a symptom rather than a diagnosis and so estimates of incidence vary. The symptom is in any case likely to be under-reported, as it is often self-limiting and a clinician may not be consulted.

Sore throats areusually due to a viral infection. Viruses commonly implicated include rhinovirus, coronavirus, influenza and parainfluenza viruses and adenovirus. In many cases, a sore throat is associated with the common cold. It may also be a symptom of influenza, or of infectious mononucleosis (glandular fever).

The most common bacterial agent is Group A beta-haemolytic streptococcus (GABS).¹ In children, it accounts for 20-40% of cases of sore throats; in adults around 10%.² Asymptomatic nasal carriage of Group A streptococci is very common, especially in very young children.³

Sore throat symptoms^{1 4}

History

The symptom of soreness on swallowing may be accompanied by fever and symptoms of upper respiratory tract infection such as headache, malaise, rhinitis and cough. Hoarseness may be present if there is laryngeal involvement.

Specific enquiry should be made about:

• Duration and severity of symptoms.

• Any self-medication/over-the-counter treatment.

• History of any comorbidities, previous risk factors, relevant past history.

• Feeling systemically unwell.

• Dysphagia.

• Rash.

• Stridor.

• Vaccination status.

• Prescribed medication, particularly those associated with neutropenia such as carbimazole, clozapine and sulfasalazine.

Examination

Examination of the throat using a tongue depressor should not be attempted in patients with stridor, as epiglottitis may be present and examination may provoke laryngeal obstruction. Drooling, leaning forward and high temperature may also be suggestive of epiglottitis. Since the introduction of Haemophilus influenzae type B (Hib) vaccination, acute epiglottitis is now extremely rare in children in the UK.

In other cases of sore throat, examination of the throat may reveal redness of the pharynx and tonsils, enlargement of the tonsils, presence of exudate and enlarged tender cervical lymph glands.

Differentiating a viral sore throat from that caused by GABS on the basis of examination is difficult. The Centor Criteria were developed to help predict bacterial infection clinically:⁵

• Tonsillar exudate.

• Tender anterior cervical lymph nodes.

• Absence of cough.

• History of fever.

A Centor score is out of 4 depending on how many of these are present. The presence of three or four of these signs (Centor score 3-4) suggests that the possibility of the patient having GABS is 32 - 56% and that antibiotic therapy may be beneficial. Conversely, patients who score 2 points or less have only a 3-17% chance of isolating GABS.

A scarlet fever-like rash (red punctate skin eruption, prominent in the skin creases), a flushed face, circumoral pallor and a 'strawberry tongue' suggest the possibility of a streptococcal infection. Recurrent sore throat with fever and lymphadenopathy may suggest glandular fever, particularly in young people.

The National Institute for Health and Care Excellence (NICE) guidance on antimicrobial prescribing in acute sore throat⁴ advises the use of either the Centor score, or the FeverPAIN score. The criteria for the latter are as follows:

• Fever in the past 24 hours.

• Purulent tonsils.

• Attend rapidly (patient attended within three days of the onset of symptoms).

• Severely Inflamed tonsils.

• No cough or coryza.

A FeverPAIN score of 4 or 5 is associated with a 62-65% chance of isolating GABS, whereas a score of 0 or 1 is associated with only a 13-18% chance of isolating GABS.

There is no evidence that bacterial sore throats are more severe than those caused by a virus, or that the duration of the illness bears any relation to the cause in most cases.¹

Differential diagnosis ¹

• Coxsackievirus infection (hand foot and mouth disease, herpangina).

• Infectious mononucleosis.

• Malignancy (pharynx, tonsils, larynx).

• Kawasaki disease.

• Diphtheria (very rare since immunisation).

• HIV.

• Herpetic pharyngitis.

• Gonococcal or chlamydial pharyngitis.

• Iatrogenic causes including mucositis from chemo or radiotherapy and neutropenia from drugs such as carbimazole or clozapine.

Investigations¹

• Investigation in primary care is not usually necessary. Some authorities recommend investigation, as this reduces the overdiagnosis of bacterial sore throat. However, in the context of UK general practice, the turnaround time for swab and serum results makes it unlikely that the results would make much difference to the immediate management of the patient. However, if symptoms and/or signs are prolonged, severe or atypical, investigation should be considered; a swab may be useful if unusual causes such as gonorrhoea or chlamydia are suspected.

• Throat swabs are not advised for routine investigation of sore throats but may be helpful in high-risk groups, or where there is treatment failure.

• Rapid antigen tests may be helpful but research shows no clear benefit over using a clinical score alone.^{2 6} They are currently not universally available in primary care.

• FBC and glandular fever screening test - these may be helpful if glandular fever is suspected.

• Antistreptolysin O (ASO) titres - these may be useful in excluding recent streptococcal infection in patients who are systemically unwell or have prolonged symptoms.

Sore throat treatment and management^{1 4}

It should be remembered that sore throat is a symptom of an underlying condition and efforts should be made to make an accurate diagnosis before considering treatment. For further details, see the separate Tonsillitis, Laryngitis and Epiglottitis articles.

General

• Reassure people that a sore throat is usually a self-limiting condition and usually resolves with or without antibiotic treatment within a week.

• Advise the use of paracetamol and/or ibuprofen to relieve symptoms of pain and fever as required.

• Advise fluid intake should be adequate to avoid dehydration.

• Advise that some people find medicated lozenges, containing a local anaesthetic and NSAID or antiseptic useful; alternatively a salt water gargle may be used. There is some evidence for use of some lozenges but little for benzydamine gargles and none for zinc lozenges, herbal remedies or acupuncture.^{7 8 9}

• Give safety-netting advice, advising the person to return if symptoms do not improve or are getting worse, and to seek urgent medical advice if they:

  • Develop difficulty breathing or stridor.

  • Start to drool.

  • Develop a muffled voice.

  • Develop severe pain.

  • Develop dysphagia.

  • Become unable to swallow adequate fluids.

  • Become systemically very unwell.

• Make sure that your patient understands the limitations of antibiotic use, in particular that:⁴

  • On average, antibiotics shorten symptoms by only around 16 hours.

  • Most people will feel better after oneweek, with or without antibiotics.

  • Antibiotics can have adverse effects including nausea or diarrhoea.

  • Complications of a sore throat are unusual, even without antibiotics.

Antibiotics

NICE has recently released guidelines for this and recommends three possible options:^{4 1}

• No antibiotics. In this case, people should be advised that antibiotics are likely to make little difference to symptoms and may make things worse due to side-effects. They should be advised to return for further assessment if their condition persists or worsens. This applies to those with a Centor score of 0/1 or a FeverPAIN score of up to 2.

• Delayed antibiotics. People should be advised as above that antibiotics are not currently indicated but that if the situation changes they may be used. They may consider using the antibiotic if the sore throat has not started to improve within 3-5 days or if symptoms worsen. They should be given the option of returning for reassessment and be advised they should do so if symptoms continue to worsen despite using the antibiotic prescription. In the absence of features suggesting immediate prescription below, consider a delayed prescription for people with a sore throat and a FeverPAIN score of 2/3. If you are concerned that the prescription may be used too soon, it can be post-dated or given directly to a pharmacy with instructions not to dispense before a particular date. No antibiotic is also a valid option for this group.

• Possible immediate prescription of antibiotics. This option should be considered for people who have a Centor score of 3/4 or a FeverPAIN score of 4/5. A delayed prescription may also be appropriate for this group, who still have only a half to two-thirds chance of having a bacterial infection in their throat. The information given earlier about antibiotics only shortening symptoms by 16 hours still applies for those with a high Centor or FeverPAIN score.

• Immediate antibiotics prescription. This option should be offered to those who are systemically unwell, have signs of a more serious illness or condition or who are at high risk of complications. Those with severe systemic infection or who appear to have a significant complication such as a quinsy, cellulitis, parapharyngeal abscess or retroperitoneal abscess should be referred to hospital. If the airway is not secure then this should be via 999 (in the UK) ambulance. Admission may also be appropriate if Kawasaki disease is suspected in a child or for those who are dehydrated due to reduced oral intake.

A discussion with patients/parents/carers should take place as to which strategy is best for individual patients. This decision should be based on a clinical assessment of severity and the presence or absence of Centor/FeverPAINcriteria.. Reassessment should be offered if the condition does not settle or if it worsens.

A Cochrane review¹⁰ concluded that antibiotics reduce symptoms and the likelihood of complications in the treatment of sore throat, but that the absolute benefits are modest. The natural history is of resolution of symptoms in 82% at one week - this includes those who are positive or negative for GABS and those who are untested. The number needed to treat for a beneficial outcome (NNTB) was 18 for symptom resolution at one week. In an unswabbed population, the NNTB for symptom resolution at 3 days was 14.4.

The Cochrane review found that the evidence on complications was in many cases old (with many trials dating from the 1950s) and noted that whilst antibiotics probably prevent rheumatic fever, there are few recent trials reporting this outcome and that the incidence of rheumatic fever in high-income countries has declined over time. The judgement as to whether to use antibiotics to reduce the risk of rheumatic fever may be different if the healthcare professional is practising in a lower-income country where rheumatic fever is more common. Antibiotics reduced the chance of acute otitis media and quinsy compared to the control group but made little or no difference compared to control for acute sinusitis. The NNTB to present one case of acute otitis media is around 200.

When an antibiotic is required, phenoxymethylpenicillin for ten days should be the first-line choice, with erythromycin or clarithromycin for five days as second-line if there is a history of allergy to penicillin. Amoxicillin or ampicillin should be avoided, especially in adolescents and young adults because, if the diagnosis is in fact glandular fever, it will produce a rash, even in the absence of allergy to penicillin.

In recent years, the use of a single dose of a corticosteroid has been suggested as a treatment for sore throat. A 2020 Cochrane review found that those given steroids were 2.4 times more likely to have complete resolution of symptoms within 24 hours and that there was no increase in adverse events, rates of recurrecne or relapse and days missed from work or school. The NNTB to prevent one person continuing to have pain at 24 hours was 5.

Limitations of the studies included the fact that most also gave antibiotics to all participants and, that very few included children and that most were carried out in the USA. The review raised concerns that widespread use of steroids for a sore throat risks medicalising this usually self-limiting condition which may result in larger cumulative doses of steroids being used over time, and pointed out that further research is needed, including into those who have comorbidities, who were largely excluded from the trials studied.¹¹

Referral¹

Complications¹

Suppurative complications

• Otitis media.

• Sinusitis.

• Peritonsillar abscess (quinsy).

• Cervical adenitis.

• Mastoiditis.

• Scarlet fever.

• Streptococcal toxic shock syndrome (rare).

• Lemierre's syndrome (rare - acute septicaemia and jugular vein thrombosis secondary to infection with Fusobacterium spp.).

Nonsuppurative complications

• Rheumatic fever (rare in developed countries but still quite prevalent in developing countries).

• Post-streptococcal glomerulonephritis.

• Guttate psoriasis - may flare up in the presence of a streptococcal infection.¹¹

Prognosis¹⁰

90% of cases of sore throat are better within a week (whether treated with antibiotics or not) and irrespective of whether the cause is viral or streptococcal. In 40% symptoms have settled within three days.