Noninfectious Pharyngitis

Pharyngitis is inflammation of the oropharynx. It is commonly referred to as sore throat. Sore throat is a very common complaint and a frequent reason for seeking medical care.

Sore throat may have an infectious or noninfectious etiology, although these sometimes overlap. Most cases are infectious, with a large proportion (up to 40 %) caused by rhinovirus and adenovirus. Other viruses including coronavirus, influenza, parainfluenza, Epstein Barr, and herpes simplex have also been implicated.

Of the bacterial sore throats, group A β-haemolytic streptococcus is most frequently (5–36 %) isolated. Other organisms to which sore throat has been attributed include Mycoplasma pneumonia and Arcanobacterium haemolyticus. Rarely, candidal infections and other fungi and parasites have also been observed.

Temperature and Humidity

Temperature and humidity affect mucus membranes and have been linked with sore throat symptoms. Heated air causes nasal pain and working regularly in a cold environment causes rhinitis and sore throat as well as changes in lung function. Humidity is also important, with the overall intensity of sick building syndrome symptoms increasing when indoor air is not humidified.

Experimentally, cold dry air induces nasal inflammation, and causes more nasal pain than humidified dry air. However, a population-based study showed that both cold temperature and low humidity appear to independently increase the risk of sore throat.

Environmental Factors

A wide variety of environmental factors have been cited as causes of sore throat, including general air pollution, and pollution encountered in indoor environments.

Patients with allergic rhinitis as well as those with post nasal drip, non-allergic rhinitis, and persistent cough may also experience sore throat as a secondary symptom.

Ambient air pollution is a common cause of sore throat. The factors implicated include ozone, nitrogen oxides, and fine dust. Nitrogen dioxide has also been implicated, as well as photochemical oxidants such as ozone. Urban living and traffic fumes are frequently associated with sore throat.

Allergies

A sore throat is a common complaint of people with allergies. Research shows that about 20% of people with allergies report a sore throat as a primary symptom. The primary culprit of an allergy-related sore throat is postnasal drip. This occurs when congestion in your nose runs down the back of your throat.

An allergen is a substance that causes an allergic reaction. After exposure to an allergen, the body may identify it as a threat, and the immune system kicks into high gear to protect against the perceived threat. The body will release histamines into the bloodstream, which is what leads to allergy symptoms, such as a sore throat.

Histamines also trigger the body to produce extra mucus to keep the mouth, nose, and throat from drying out. When the immune system releases too many histamines after being exposed to an allergen, this vigorous response leads to congestion, postnasal drip, and a sore throat.

Common allergens that may cause post nasal drip and sore throat include animal dander (e.g., cats, dogs), cigarette smoke, dust mites, and mold.

Smoking

Smoking is a risk factor for sore throat in both smokers themselves and in those exposed to secondary smoke (passive smoking).

Smoking also makes a person more susceptible to health conditions that can cause a sore throat, including a cold, the flu, and respiratory tract infections. This is because smoking weakens the functioning of the immune system.

Snoring

Snoring is frequently associated with sore throat, and the two have risk factors such as smoking in common. A high frequency of sore throat is a risk factor for habitual snoring in children and sore throat was reported by over half of those snoring children who were subsequently diagnosed with obstructive sleep apnea. Sore throat may also be associated with obstructive sleep apnea in adults.

Vocal Fatigue

Shouting and voice loading may cause sore throat, as reported by people in professions that require use (and overuse) of their voice for their work. For example, aerobics instructors have reported an increased incidence of sore throat unrelated to illness since beginning instructing and the frequency of aerobics classes has been shown to significantly correlate with sore throat symptoms in instructors. Sore throat is also reported by school teachers.

Muscle tension dysphonia, or voice strain caused by muscle tightness, can occur even when there is no damage to the vocal cords.

Drug-induced Pharyngitis

Drug-induced sore throat is a notable adverse effect of some medications, including angiotensin-converting enzyme inhibitors and chemotherapy agents. Sore throat is also a common problem in asthmatics taking inhaled corticosteroids, although these data may be in part confounded by a potential steroid-induced increased susceptibility to infection, including mycoses.

Concomitant Illness

Concomitant illness can directly result in sore throat. For example, Kawasaki disease (a mucocutaneous vasculitis) typically causes pharyngitis in both adults and children. Furthermore, chronic pharyngitis is a common manifestation of gastroesophageal reflux disorder.

Other illnesses may be associated with sore throat due to a consequent increased predisposition to infection. Patients with newly diagnosed thyroiditis report sore throat as a first symptom.

Sick Building Syndrome

Indoor air pollution causes sick building syndrome, including sore throat. The underlying source of pollutants is thought to be poorly maintained moisture-related heating, ventilating, and air-conditioning components such as cooling coils and humidification systems. Thus, symptom prevalence is higher in buildings ventilated mechanically or with air-conditioning compared with naturally ventilated buildings.

Occupational Pharyngitis

Occupational or hazard-associated irritants that have been reported to cause sore throat include particulates, fumes, chemicals, and odors.

Particulates and fumes from a wide variety of industries have been implicated in sore throat, including pulp mills, woodworking, cement works, brick kilns, and factory exhaust emissions.

The burning of gas creates multiple pollutants, including nitrogen oxides, particulates, and volatile organic compounds. Gas-related pollution has been linked with sore throat. Cooking and fires are important sources of pollutants, and they may increase episodes of sore throat.

A variety of chemicals have been reported to cause sore throats including organic screen-printing solvents, boron oxide, and borax dust fluorinated hydrocarbons.

Sore throat is also a frequently reported (72 %) symptom in people with multiple chemical sensitivity syndrome.