A sore throat is pain, scratchiness or irritation felt in the throat. Clinically it is often described as pharyngitis, meaning inflammation of the back of the throat. Although it is one of the most frequent reasons people seek primary care, most episodes are mild and self-limiting. The main clinical problem is distinguishing the minority of cases caused by bacteria, which need antibiotics, from the majority caused by viruses, which do not.
Causes
Viral infections
Viral infections account for most cases. Viruses that cause the common cold and the flu also cause most sore throats. Other viral illnesses that can produce throat pain include measles, chickenpox and COVID-19 (see the COVID-19 pandemic). In New Zealand guidance, glandular fever (Epstein-Barr virus) is named as a cause in young people. Estimates vary by setting, but one widely cited figure is that about 90% of sore throats are caused by viral infections.
Bacterial infections
Bacterial causes are less common. The most important is Streptococcus pyogenes, also called group A streptococcus (GAS). This bacterium causes strep throat and other illnesses. Strep throat has its highest incidence in children and adolescents; although it can occur in adults, strep throat is more common in children between ages 5 and 15.
Other causes
Non-infectious and other infectious causes include:
- Allergy. The reaction might be to molds, dust, pollen or flecks of skin shed by dogs, cats, and other animals with fur or feathers. Drainage of mucus down the back of the throat can also irritate it. (Allergic conditions are discussed separately.)
- Dry or irritated air. Dry indoor air can make the throat feel rough and scratchy. Mouth breathing from a blocked nose has a similar effect.
- Smoke and pollutants. Smoking, vaping and air pollution all irritate the throat lining.
- Reflux. If GERD or allergies are causing your sore throat, using acid-suppressing medication for reflux may help. See gastro-oesophageal reflux disease.
- Local infections of nearby structures. tonsillitis, laryngitis and sinus infections can produce similar symptoms.
Diagnosis
Most clinicians first try to estimate whether a sore throat is viral or streptococcal from history and examination. Several scoring systems support this decision.
Centor and McIsaac criteria
The Centor criteria were developed as a method to quickly diagnose the presence of Group A streptococcal infection in adults seen in an urban emergency room. Four findings each add one point: fever, absence of cough, tonsillar swelling or exudate, and tender anterior cervical lymph nodes. The score was later modified; the modified version added age and was validated in 600 adults and children. The age-adjusted version is known as the McIsaac score.
Published risk estimates differ across populations. In one modified-Centor summary, the GAS risk was 1% to 17% at scores of 2 or lower and 28% to 53% at scores of 3 or higher. A Malaysian validation study found that a Centor score < 3 is favourable for excluding a diagnosis of GAS pharyngitis, while higher scores required confirmation.
These scores have clear limits. One review noted that both tools were only fair at identifying true strep cases, and neither was accurate enough on its own to "rule in" infection. A low score is more useful for excluding bacterial infection than for confirming it.
Laboratory testing
Available diagnostic tests include throat culture and rapid antigen detection testing. Throat culture is considered the diagnostic standard, although the sensitivity and specificity of rapid antigen detection testing have improved significantly. Testing is generally reserved for patients whose clinical score suggests a moderate or high probability of GAS.
Clinical features that favour bacterial causes
Cough, coryza, and diarrhea are more common with viral pharyngitis. Features more typical of streptococcal disease include fever above 38 °C, tonsillar exudates and enlarged, tender lymph nodes in the neck.
Treatment
Viral sore throat
Most viral sore throats need no specific treatment. Most sore throats get better after 2 or 3 days and go away completely in 7 to 10 days without any treatment. Symptomatic relief is the usual goal. Options include:
- Analgesics. If a sore throat is caused by a virus, the best medical treatment is taking a nonsteroidal anti-inflammatory (NSAID) pain reliever such as ibuprofen. Where NSAIDs cannot be used, you can also try acetaminophen. It doesn't reduce the inflammation as well, but it does help pain. Aspirin should not be given to young children.
- Lozenges and sprays. Medicated lozenges containing a local anaesthetic, antiseptic or anti-inflammatory agent may help, though evidence for topical sprays used alone is limited.
- Salt-water gargle. The NHS advises dissolving half a teaspoon of salt in a glass of warm water, gargling, and spitting the liquid out rather than swallowing it.
- Fluids and humidity. Warm drinks and soup may soothe, and a humidifier can help when the indoor air is dry, particularly at night.
Bacterial (streptococcal) sore throat
For sore throat caused by bacteria (GAS), treatment with antibiotics may help the person get better faster, reduce the risk that the bacterial infection spreads, and lower the risk of complications. Antibiotics are not used for viral infections because antibiotics won't help at all if your sore throat is caused by viruses. For streptococcal infection, a full course is important: in New Zealand guidance, if you have strep throat, you will need to take antibiotics for 10 days.
Complications
Untreated streptococcal pharyngitis can lead to rheumatic fever, a delayed autoimmune complication. Acute rheumatic fever is a delayed autoimmune complication of Group A Streptococcal pharyngitis. The risk of rheumatic fever is higher in some populations, and public-health guidance for those groups recommends early checking of any sore throat. Other suppurative complications include peritonsillar and retropharyngeal abscesses.
When to seek care
Warning signs described in general guidance include a severe sore throat with high fever that lasts more than a day or two, difficulty sleeping because your throat is blocked by swollen tonsils or adenoids, or a red rash. Difficulty breathing or inability to swallow requires emergency care. Sore throat that does not improve after several days also warrants medical review.
Prevention
Hand hygiene and avoiding close contact with people who have colds or other contagious infections reduce the spread of the viruses and bacteria involved. Avoiding smoking and inhaling second-hand smoke reduces irritation of the throat lining.
References
- Sore throaten.wikipedia.org
- Sore throat-Sore throat - Symptoms & causes - Mayo Clinicmayoclinic.org
- Sore throathealthnz.govt.nz
- Sore throathealthify.nz
- Soothing a Sore Throatnewsinhealth.nih.gov
- Have a Sore Throat? 3 Things You Should Knowyalemedicine.org
- Centor criteriaen.wikipedia.org
- Diagnosis and Treatment of Streptococcal Pharyngitisaafp.org
- Pharyngitiscfp.ca
- Diagnostic Accuracy of Centor Score for Diagnosis of Group A Streptococcal Pharyngitis among Adults in Primary Care Clinics in Malaysiancbi.nlm.nih.gov
- Centor vs McIsaac Score: Strep Throat Testing Guidehome.hippoed.com
- Physicians’ knowledge and adherence to Centor Criteria for preventing acute rheumatic fever in Jeddah, Saudi Arabiancbi.nlm.nih.gov
- Sore Throat: When to See a Doctorosteopathic.org
- Sore throat - NHSnhs.uk
- NHS 111 Wales - Health A-Z : Sore throat111.wales.nhs.uk
- Acute pharyngitismedicalguidelines.msf.org
- Diagnostic Accuracy of Centor Score for Diagnosis of Group A Streptococcal Pharyngitis among Adults in Primary Care Clinics in Malaysia - PMCpmc.ncbi.nlm.nih.gov