A decongestant or nasal decongestant is a type of drug which is used to relieve nasal congestion.
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.
The active ingredients in most ingested decongestants are
pseudoephedrine or phenylephrine. Decongestant nasal sprays and eye
drops often contain oxymetazoline and are used for topical decongestion.
Pseudoephedrine acts indirectly on the adrenergic receptor system while
phenylephrine and oxymetazoline are direct agonists. The effects are
not limited to the nose and these medicines may cause hypertension (high
blood pressure) through vasoconstriction, but most decongestants are
not pronounced stimulants due to lack of response from the other
adrenoreceptors. Besides hypertension, common side effects include
sleeplessness, anxiety, dizziness, excitability, and nervousness.
Decongestants are normally paired with antihistamines to
lessen this effect, but the combination of both classes of drugs do not
necessarily cancel the side effects of each other.
Topical nasal or ophthalmic decongestants quickly develop
tachyphylaxis (''a rapid decrease in the response to a drug after
repeated doses over a short period of time'').
Long-term use is not
recommended since these agents lose effectiveness after a few days.
Further Reading
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"Decongestant"
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