Decongestants are used to decrease nasal congestion caused by stimulation of the alpha¹-adrenergic receptors on nasal blood vessels, which causes vasoconstriction, in turn shrinking mucous membranes and relieving congestion.¹ Decongestants are available orally and topically. Oral decongestants have a delayed onset with prolonged and less potent effects, while topical decongestants produce rapid and potent effects. Topical steroid decongestants are discussed in Chapter 30.