Topical decongestants, highly effective vasoconstrictors, offer quick relief from swelling of the mucous membranes and nasal congestion. The most commonly used topical decongestants include xylometazoline, tetrahydrozoline, phenylephrine, naphazoline and epinephrine. These are used to treat symptoms of common cold, rhinitis and sinusitis.  Phenylephrine, used in both systemic and topical decongestants, is one of the common sinus decongestants.

Topical decongestants contain sympathomimetic amines and their derivatives, and propylhexedrine. A sympathomimetic drug imitates the central nervous system actions. An amine is a compound containing ammonia. Sympathomimetic amines include epinephrine and phenylephrine. The derivatives of sympathomimetic amines include naphazoline, oxymetazoline and tetrahydrozoline are.

Phenylephrine is a principal component of many nasal drops and sprays.

Naphazoline is used for ophthalmic and nasal solutions. The solutions are available in prescription and over-the-counter (OTC) forms. The ocular solution treats itching and irritation in the eyes. The nasal drops relieve the congestion.

Oxymetazoline, a nasal spray, is sold as OTC. It is also used in ocular drops that reduce redness in the eyes.

 Tetrahydrozoline, a nasal decongestant, is a prescription drug.

A topical decongestant stimulates alpha-adrenergic receptors present in the nasal blood vessels’ muscle, reducing blood flow to the nose. Pharmacokinetics of the topical decongestant is different than that of systemic. Topical constricts the arterioles by directly acting on the receptors found in the nose muscle. The direct action ensures that only a small quantity of the decongestant is absorbed. Less absorption minimizes the chances of drug interactions. However, it interacts with monoamine oxidase (MAO) inhibitor, causing hypertension and severe headache. If used with a beta blocker, hypertension and bradycardia may occur. When used with methyldopa, the pressor response increases. Reduction in blood supply and capillary permeability resolve swelling of the membranes. Thus, sinus drainage improves, nasal passages become clear and the Eustachian tubes open.