General Medical Information

Decongestants

Shawn D. Newlands

Decongestants are orally (pseudoephedrine, phenylephrine, phenylpropanolamine) or topically (phenylephrine, oxymetazoline, xylometazoline) administered a-adrenergic agonists. Pseudoephedrine, phenylephrine, and phenylpropanolamine act on the respiratory mucosa by stimulating the release of noradrenaline from sympathetic nerve endings and by direct stimulation of a-adrenergic receptors in blood vessels with negligible to slight b-receptor (central nervous system) activity. Over-the-counter derivatives of these oral decongestants can be cost-effective alternative treatments for nasal congestion as well. They have no effect on the inflammatory cascade and thus do not alter itching, sneezing, or nasal secretion.

Oral decongestant agents are most efficacious used alone to manage vasomotor rhinitis and infectious rhinitis. They are used to manage allergic rhinitis in combination with antihistamines to control nasal congestion. Patients with nonallergic rhinitis and eosinophilia also may respond to combined antihistamine and decongestant therapy. Systemic effects of oral decongestants include high blood pressure, palpitations, nervousness, irritability, headaches, palpitations, tachycardia, and urinary retention. These medicines should be avoided by patients who have hypertension, coronary artery disease, glaucoma, diabetes, urinary retention, or hyperthyroidism. An additional contraindication to the use of oral decongestants is concurrent use of monoamine oxidase inhibitors or tricyclic antidepressants. Oral decongestants should not be used in the first trimester of pregnancy and should not be used by high-level athletes because they are banned as performance-enhancing drugs. Topical decongestant preparations cause rebound congestion through down-regulation of a-adrenergic receptors, which makes the nasal blood vessels less sensitive to endogenous and exogenous agonists. These medicines are limited to short-term use but are helpful in the management of infectious rhinitis, eustachian tube dysfunction, and acute exacerbations of allergic rhinitis.