Sore Throat: Causes

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Exploring the causes of a sore throat

A sore throat is a common symptom during a flu virus infection.1,2 Here we take a closer look at what causes a sore throat during the flu, and what other differential diagnoses may need to be considered.

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The role of inflammation in a sore throat

An infection from the influenza virus triggers an immune response within the infected patient, resulting in the release of various chemotactic, proinflammatory, and immunoregulatory cytokines.3 The activity of these inflammatory mediators is responsible for triggering various symptoms typical of the flu, including a sore throat.4

  • The immune response

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    The body’s immune response to infection

    Infection by the influenza virus triggers the body’s epithelial cells and leukocytes to release various cytokines to activate cells of the immune system. Each group of cytokines plays a role, such as:3

    • Upregulation of immune cell expression
    • Direction of leukocyte migration towards the infection site

    The presence of cytokines, as well as the release of prostaglandins from triggered cells, are thought to be the cause of a painful throat experienced during the flu.4

  • Other Causes of a Sore Throat

    A sore throat may arise from causes other than the flu

    A painful throat is not a symptom exclusive to an influenza infection, and may be due to other causes, both infective and non-infective.5

    Woman sneezing

    Other viral illnesses

    These include the common cold, measles, chickenpox, and croup.5

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    Bacterial illnesses

    The most common bacteria associated with a sore throat is streptococcus pyogenes, causing what is known as a strep throat.5

    Watery eyes


    Reactions to allergens such as mold, dust, pollen, and animal dander can include a sore throat.5

    Outdoor nitrogen dioxide is increasingly being implicated in a wide range of disorders. For example, increased risk of otitis media, eczema, ear/ nose/throat infections and sensitization to food allergens, in children, as well as increased blood coagulability after periods of elevated ambient exposure in adults, have recently been reported.6

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