Decongestant

A decongestant is a broad class of medications used to relieve nasal congestion. Generally, they work by reducing swelling of the mucous membranes in the nasal passages.

Mechanism

Most decongestants cause response from adrenoreceptor a₁, chiefly responsible for vasoconstriction (a₂ modulates adrenaline/noradrenaline levels, b₁ is the most stimulating and increases cardiac output, b₂ dilates the bronchial walls, and b₃ induces lipolysis). The effects are not limited to the nose and these medicines can increase hypertension (blood pressure) through vasoconstriction, but most decongestants are not pronounced stimulants due to lack of response from the other adrenoreceptors.

These 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. Long-term use is not recommended since these agents lose effectiveness after a few days.

Administration

These agents are usually administered topically (by the intranasal route) or orally.

Examples

The most common oral decongestants are pseudoephedrine and phenylephrine; phenylpropanolamine (PPA) is another, although it is no longer available in the United States. Oxymetazoline and phenylephrine are commonly available topical decongestants (nasal sprays).

See also

• Nasal congestion (includes non-pharmacological remedies)
• Topical decongestant
• Adrenoreceptor
• Expectorant