Definition of Pharyngitis

Pharyngitis is an inflammation of the throat. In most cases it is quite painful, and is the most common cause of a sore throat.

Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic. Pharyngitis can result in very large tonsils which cause trouble swallowing and breathing. Pharyngitis can be accompanied by a cough or fever, for example, if caused by a systemic infection.

Most acute cases are caused by viral infections (40–80%), with the remainder caused by bacterial infections, fungal infections, or irritants such as pollutants or chemical substances. Treatment of viral causes are mainly symptomatic while bacterial or fungal causes may be amenable to antibiotics and anti-fungal respectively.

Pharyngitis is a type of inflammation, most commonly caused by an upper respiratory tract infection. It may be classified as acute or chronic. An acute pharyngitis may be catarrhal, purulent or ulcerative, depending on the virulence of the causative agent and the immune capacity of the affected individual. Chronic pharyngitis is the most common otolaringologic disease and may be catarrhal, hypertrophic or atrophic.

If the inflammation includes tonsillitis, it is called pharyngotonsillitis. Another sub classification is nasopharyngitis (the common cold).

Cause of Pharyngitis

The majority of cases are due to an infectious organism acquired from close contact with an infected individual.



These comprise about 40–80% of all infectious cases and can be a feature of many different types of viral infections.

  • Adenovirus – the most common of the viral causes. Typically the degree of neck lymph node enlargement is modest and the throat often does not appear red, although it is very painful.
  • Orthomyxoviridae which cause influenza – present with rapid onset high temperature, headache and generalised ache. A sore throat may be associated.
  • Infectious mononucleosis (“glandular fever”) caused by the Epstein-Barr virus. This may cause significant lymph gland swelling and an exudative tonsillitis with marked redness and swelling of the throat. The heterophile test can be used if this is suspected.
  • Herpes simplex virus can cause multiple mouth ulcers.
  • Measles
  • Common cold: rhinovirus, coronavirus, respiratory syncytial virus, parainfluenza virus can cause infection of the throat, ear, and lungs causing standard cold-like symptoms and often extreme pain.


A number of different bacteria can infect the human throat. The most common is Group A streptococcus, however others include Corynebacterium diphtheriaeNeisseria gonorrhoeaeChlamydophila pneumoniae, and Mycoplasma pneumoniae.

Streptococcal Pharyngitis or strep throat is caused by group A beta-hemolytic streptococcus (GAS). It is the most common bacterial cause of cases of pharyngitis (15–30%). Common symptoms include fever, sore throat, and large lymph nodes. It is a contagious infection, spread by close contact with an infected individual. A definitive diagnosis is made based on the results of a throat culture.

Fusobacterium necrophorum are normal inhabitants of the oropharyngeal flora. Occasionally however it can create a peritonsillar abscess. In 1 out of 400 untreated cases Lemierre’s syndrome occurs.

Diphtheria is a potentially life threatening upper respiratory infection caused by Corynebacterium diphtheriae which has been largely eradicated in developed nations since the introduction of childhood vaccination programs. 

A few other causes are rare, but possibly fatal, and include parapharyngeal space infections: peritonsillar abscess (“quinsy”), submandibular space infection (Ludwig’s angina), and epiglottitis.

Some cases of pharyngitis are caused by fungal infection such as Candida albicans causing oral thrush.


Pharyngitis may also be caused by mechanical, chemical or thermal irritation, for example cold air or acid reflux. Some medications may produce pharyngitis such as pramipexole and antipsychotics.

Signs and Symptoms of Pharyngitis

A sore throat is the main symptom. Other symptoms may include :

  • Sneezing
  • Fever
  • Cough
  • Fatigue
  • Body aches
  • Chills
  • Joint pain and muscles aches
  • Skin rashes
  • Enlarged lymph nodes in neck and armpits
  • Swollen tonsils
  • Headache
  • Voice change
  • Loss of appetite
  • Swollen spleen
  • Liver inflammation

Risk Factors for Pharyngitis

These are risk factors:

  • Cold and flu seasons
  • Having close contact with someone who has a sore throat or cold
  • Smoking or exposure to secondhand smoke
  • Frequent sinus infections
  • Allergies
  • Attending daycare
  • Group A β-hemolytic streptococci: risk of rheumatic heart disease or glomerulonephritis
  • Corynebacterium diphtheriae: myocarditis, peripheral neuritis
  • Immunosuppression
  • Oral sex; at risk for gonococcal pharyngitis and Chlamydial trachomatis pharyngitis
  • Recent illness

Diagnosis of Pharyngitis

It is hard to differentiate a viral and a bacterial cause of a sore throat based on symptoms alone. Thus often a throat swab is done to rule out a bacterial cause.

The modified Centor criteria may be used to determine the management of people with pharyngitis. Based on 5 clinical criteria, it indicates the probability of a streptococcal infection.

One point is given for each of the criteria:

  • Absence of a cough
  • Swollen and tender cervical lymph nodes
  • Temperature >38.0 °C (100.4 °F)
  • Tonsillar exudate or swelling
  • Age less than 15 (a point is subtracted if age >44)

The McIsaac criteria adds to the Centor:

  • Age less than 15: add one point
  • Age greater than 45: subtract one point

The Infectious Disease Society of America however recommends against empirical treatment and considers antibiotics only appropriate following positive testing. Testing is not needed in children under three as both group A strep and rheumatic fever are rare, except if they have a sibling with the disease.

Prevention from Pharyngitis

Prevention of pharyngitis includes:

  • Wash your hands frequently.
  • Use a humidifier if the air in your home is dry.
  • Avoid sharing food, drinking glasses or utensils.
  • Avoid exposure to others who have a sore throat.
  • Avoid crowded areas during cold and flu season.
  • Drink enough fluids to prevent dehydration.
  • Do not smoke and avoid exposure to secondary smoke.
  • Wear a filtering mask when cleaning to avoid inhaling dust or airborne particles from cleaning products.
  • Keep vaccinations up to date.

Treatment of Pharyngitis

The majority of time treatment is symptomatic. Specific treatments are effective for bacterial, fungal, and herpes simplex infections.


  • Analgesics such as NSAIDs and acetaminophen can help reduce the pain associated with a sore throat. (Note: Don’t use salicylates, like aspirin, for influenza: Increased risk of Reye’s syndrome)
  • Steroids (such as dexamethasone) have been found to be useful for severe pharyngitis.
  • Viscous lidocaine relieves pain by numbing the mucus membranes.
  • Antibiotics are useful if a bacterial infection is the cause of the sore throat. For viral infections, antibiotics have no effect.
  • Oral analgesic solutions, the active ingredient usually being Phenol, but also less commonly Benzocaine, Cetylpyridinium chloride and/or Menthol. Chloraseptic and Cēpacol are two examples of brands of these kinds of analgesics.


Alternative medicines are promoted and used for the treatment of sore throats. However, they are poorly supported by evidence.