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Pharyngitis - Causes and Pathogenesis
Last reviewed: 04.07.2025
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Causes of pharyngitis
Acute pharyngitis as an independent disease is observed with direct exposure to an infectious agent or various irritants (hot or cold food, inhalation of cold air or air containing harmful impurities, industrial dust, smoking, alcohol, alimentary irritant, etc.). When acute pharyngitis is one of the manifestations of an acute respiratory viral infection, it develops under the influence of the same causes as the underlying disease. The etiological factor of acute pharyngitis can be viruses, microbial pathogens, fungi. Viral etiology of acute pharyngitis is noted in approximately 70% of cases; the causative agents in this case are rhinoviruses coronaviruses, respiratory syncytial virus, adenoviruses, enteroviruses, influenza virus, parainfluenza, etc. During autumn epidemics, rhinoviruses are responsible for more than 80% of cases of acute respiratory infections. Viral infection may be only the first phase of the disease - it "paves the way" for subsequent bacterial infection. Among the bacterial pathogens of acute tonsillopharyngitis, the main role is played by beta-hemolytic streptococcus group A and other groups, with which 31% and 15% of all cases of the disease are associated, respectively. Microorganisms such as Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma, Staphylococcus aureus, Moraxella, Klebsiella and other microflora, usually found in the nasopharynx in a non-pathogenic form, are encountered.
Acute inflammation of the pharynx can also develop as a result of allergic or traumatic effects, as well as under the influence of various irritating factors: hot drinks, acids, alkalis, radiation, etc.
The development of chronic pharyngitis in most cases is caused by local long-term irritation of the mucous membrane of the pharynx. Chronic pharyngitis is promoted by repeated acute inflammation of the pharynx, chronic tonsillitis, long-term inflammatory diseases of the nose and paranasal sinuses, and impaired nasal breathing. With constantly difficult nasal breathing, pharyngitis can be caused not only by switching to breathing through the mouth, but also by the abuse of vasoconstrictor drops that flow from the nasal cavity into the pharynx and have an anemic effect there. Symptoms of chronic pharyngitis can develop with the so-called postnasal syndrome, when pathological secretions flow from the nasal cavity or paranasal sinuses along the back wall of the pharynx.
The development of chronic pharyngitis can be caused by exposure to unfavorable climatic and environmental factors (dust, hot, dry or smoky air, chemicals), smoking, alcohol abuse, etc.
The cause of the disease may be diseases of the gastrointestinal tract (chronic gastritis, cholecystitis, pancreatitis, intestinal dysbacteriosis). For example, the development of chronic pharyngitis is often caused by the entry of acids from stomach contents into the throat during sleep with gastroesophageal reflux and hernia of the esophageal opening of the diaphragm.
Chronic pharyngitis can be caused by endocrine and hormonal disorders (menopause, hypothyroidism), allergies, hypo- or avitaminosis A, dental caries, alcohol consumption, spicy irritants and excessively hot or cold food. Diabetes mellitus, cardiac, pulmonary and renal diseases can also be the cause of chronic pharyngitis. Finally, chronic pharyngitis can also occur with a number of chronic infectious diseases, such as tuberculosis.
Pathogenesis of pharyngitis
Morphological changes in acute pharyngitis are characterized by edema and infiltration of cellular elements of the mucous membrane, expansion and injection of vessels, and desquamation of the epithelium. The inflammatory reaction is usually more pronounced in places where lymphoid tissue accumulates - in the area of the vault of the nasopharynx, near the mouths of the auditory tubes, on the back and side walls of the pharynx.
In the catarrhal form of chronic pharyngitis, persistent diffuse venous hyperemia and pastosity of the mucous membrane are revealed due to the expansion and stasis of small-caliber veins: perivascular cellular infiltration is observed.
The hypertrophic form of pharyngitis is characterized by thickening of all layers of the mucous membrane, an increase in the number of epithelial rows. The mucous membrane becomes thicker and denser, blood and lymphatic vessels are dilated, lymphocytes are determined in the perivascular space. Lymphoid formations, normally scattered over the mucous membrane in the form of barely noticeable granules, significantly thicken and expand, often due to the fusion of adjacent granules: hypersecretion is noted, the mucous membrane is hyperemic. The hypertrophic process can be localized mainly on the back wall of the pharynx (granular pharyngitis) or on its lateral parts (lateral hypertrophic pharyngitis).
Atrophic chronic pharyngitis is characterized by a sharp thinning and dryness of the mucous membrane of the pharynx; in severe cases it is shiny, "varnished". The size and number of mucous glands are reduced; desquamation of the epithelial cover is observed.
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