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The Effects of Histamine

Allergies effect large cross sections of the population throughout the world. According to the Center for Disease Control (CDC), as many as 12.2 million Americans seek physician services in hospitals and doctors offices each year for allergies. The severity of an allergic reaction depends largely on histamine in the body.

  1. Definition

    • Histamine is a protein that is stored in the mast cells of the body (mast cells are located in the loose connective tissues of the body's organs, including the skin). When the body comes in contact with a foreign invader (such as pollen or another substance the body views as an intruder), it reacts by initiating the body's natural immune response. Part of this response is the release of histamine. Once the histamine reaches the site of intrusion, it can cause one of three effects.

    Inflammation

    • One of the most common effects of histamine is inflammation. Histamine causes inflammation directly and indirectly. When histamine enters the affected area, the vessels in the surrounding area experience an increase of permeability. This allows an increase in blood and immune cells in the area causing swelling. Indirectly, histamine also triggers the release of cytokins. These cells travel to surrounding leukocytes and increase the inflammatory reaction.

    Smooth Muscles

    • Histamine also has an effect on the smooth muscles of the body. This is one of the main reasons why histamine is responsible for most asthma attacks. When the body responds to a substance it interprets as an allergen, the histamine released causes the smooth muscles in the surrounding area to contract. When an allergen enters the airway this can cause a potentially deadly reaction as the smooth muscles of the airways contract and constrict the amount of airflow that is able to get to the lungs.

    Mucus Production

    • Histamine also effects the production and viscosity. In the body are two types of histamine receptors, H1 and H2. When an H1 receptor is activated, the body increases how much mucus is being produced so that the mucus can trap the allergen or other invader. When the H2 receptor is activated, the body also increases the viscosity (thickness) of the mucus making it easier for foreign particles to get trapped in it.

    Antihistamines

    • Whether it's allergy season or you suffer from chronic allergies, a antihistamine may be employed to help block the effects of histamine in the body. Antihistamines are medications that block the histamine receptors and help reduce the amount of histamine that is released by the body.

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