Decongestant

A decongestant (or nasal decongestant) is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter of which has disputed efficacy).

These are alpha-agonists which on topical application as dilute solution (0.05-0.1%) produce local vasoconstriction. Regular use of these agents for long periods should be avoided because mucosal ciliary function is impaired: atrophic rhinitis and anosmia can occur due to persistent vasoconstriction.

Decongestants can be absorbed from the nose via an inhaler and produce systemic effects, mainly CNS stimulation and rise in blood pressure. These drugs should be used cautiously in hypertensives and in those receiving MAO inhibitors.

The vast majority of decongestants act via enhancing norepinephrine (noradrenaline) and epinephrine (adrenaline) or adrenergic activity by stimulating the α-adrenergic receptors. This induces vasoconstriction of the blood vessels in the nose, throat, and paranasal sinuses, which results in reduced inflammation (swelling) and mucus formation in these areas.

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