Adecongestant, ornasal decongestant, is a type ofpharmaceutical drug that is used to relievenasal congestion in theupper respiratory tract. The active ingredient in most decongestants is eitherpseudoephedrine orphenylephrine (the latter of which hasdisputed effectiveness). Intranasalcorticosteroids can also be used as decongestants andantihistamines can be used to alleviaterunny nose,nasal itch, andsneezing.[1]
Topical decongestants ontopical application as dilute solution (0.05–0.1%) produce localvasoconstriction.
Regular use of decongestants for long periods should be avoided because mucosal ciliary function is impaired: atrophic rhinitis andanosmia (loss of the sense of smell) can occur due to persistent vasoconstriction.
Decongestants can be absorbed from the nose via aninhaler and produce systemic effects, mainlycentral nervous system stimulation and rise inblood pressure. These drugs should be used cautiously in hypertensives and in those receivingmonoamine oxidase inhibitors (MAOIs), as they can causehypertensive crisis.
Expectorants such asguaifenesin are a related type of drug which help to clearmucus.
Decongestants are used to treatnasal congestion, for instance inallergies,infections like thecommon cold,influenza, andsinus infection, andnasal polyps. Decongestants are also used to reduce redness in the treatment of simple conjunctivitis.
A 2016Cochranereview found insufficient evidence to support the use of intranasal corticosteroids in the relief of common cold symptoms;[2] however, the review was based on three trials and the quality of the evidence was regarded as very low.[2]
The vast majority of decongestants act via enhancingnorepinephrine (noradrenaline) andepinephrine (adrenaline) oradrenergic activity by stimulating theα1-adrenergic receptor since they mediate vasoconstriction and constricting nasal vasculature causes decongestion of nasal mucosa. This inducesvasoconstriction of theblood vessels in thenose,throat, andparanasal sinuses, which results in reducedinflammation (swelling) andmucus formation in these areas.
Decongestant nasal sprays and eye drops often containoxymetazoline and are used fortopical decongestion. Pseudoephedrine acts indirectly on the adrenergic receptor system, whereas phenylephrine and oxymetazoline are directagonists. The effects are not limited to the nose, and these medicines may causehypertension (high blood pressure) throughvasoconstriction; it is for this reason that people with hypertension are advised to avoid them. Most decongestants, however, 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.
Topical nasal or ophthalmic decongestants quickly developtachyphylaxis (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.
