Nasal Allergy Medications (cont.)

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Throughout this section on nasal allergy management, the various treatments will be referred to as "controllers" or "relievers" of symptoms. Controllers are used to prevent symptoms by interfering with the underlying causes of the inflammatory response or the actions of chemical mediators. Examples of controllers include:

  • Drugs that block the attachment of histamine to special receptors on cells (antihistamines)
  • Drugs that prevent mast cells from releasing chemicals (cromolyn)
  • Drugs that prevent or reduce inflammation that arises from an allergic reaction (steroids)

Other medications, called relievers, are used to alleviate symptoms without affecting the inflammation. They are also called "rescue" medications and in general provide only temporary relief. Relievers should only be used alone for mild or intermittent symptoms. Examples include:

  • Drugs that narrow (constrict) the blood vessels in the nasal membranes, thereby helping "shrink" swollen tissues and relieve congestion (decongestants)
  • Drugs that reduce mucous production by blocking the nerve supply to the mucous glands (anticholinergics)

What are antihistamines?

The term "antihistamine" is a combination of two words; "anti-" means against, and "histamine" is a naturally occurring chemical that is released by the mast cells. Histamine is responsible for many of the signs and symptoms of allergic reactions, for example, swelling of the lining of the nose, sneezing, and itchy eyes. Histamine is released from histamine-storing cells (mast cells) and then attaches to other cells that have histamine receptors. The attachment of the histamine to the receptors causes these cell to be "activated," releasing other chemicals which produce the effects (symptoms, see previous sectiohn "Nasal allergy symptoms: an overview of treatments") that are associated with nasal allergies.

How do antihistamines work?

Human cells have three different types of histamine receptors (H1, H2, and H3). Histamine works by attaching itself to these receptors on the surface of cells and thereby causing its effects. It is mainly through the H1 receptors that histamine causes symptoms of nasal allergy. Antihistamines compete with histamine to attach to these same H1 receptor sites, thereby preventing histamine from binding to them. This action prevents histamine from causing allergic symptoms because the antihistamines that bind do not activate the cells.

Histamines can cause symptoms of swelling, sneezing, itching (nose, throat, roof of mouth), and a runny nose through the nostrils or down the back of the throat (post-nasal drip). Antihistamines are effective in treating the sneezing, post-nasal drip, and itching. They usually begin working between 30 to 60 minutes after being taken. However, histamine is only one of the many chemicals involved in the allergic reaction, which explains why relief from antihistamines is usually only partial.



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