Naphazoline

Naphazoline is a topical sympathomimetic decongestant used in both nasal and ophthalmic preparations. It is an imidazoline derivative that acts as a direct-acting alpha-adrenergic receptor agonist, causing vasoconstriction of the mucosal and conjunctival vessels. This reduces swelling and redness, providing relief from nasal congestion and eye irritation.

In nasal use, naphazoline helps relieve congestion due to colds, allergies, or sinusitis. In ophthalmic formulations, it is used to lessen conjunctival redness and irritation. The onset of action is rapid, and effects typically last for several hours, though duration can vary by preparation and individual.

Common formulations include nasal sprays or drops and ophthalmic drops or solutions. Because of its vasoconstrictive action, naphazoline should be used at the lowest effective dose for the shortest duration necessary. Prolonged or frequent use can lead to tachyphylaxis and, in the nasal form, rhinitis medicamentosa (rebound congestion) upon withdrawal.

Adverse effects are usually local and mild, such as stinging, dryness, or irritation of the nose or eye. Systemic effects are uncommon but can occur, especially with excessive use, and may include headache, tachycardia, hypertension, and insomnia. Cautions include avoiding use in patients with hypertension, cardiovascular disease, hyperthyroidism, or narrow-angle glaucoma, and avoidance during pregnancy or in young children unless directed by a clinician. Interactions can occur with monoamine oxidase inhibitors and other sympathomimetics, potentially raising blood pressure or causing hypertensive crises.

Naphazoline is generally available over the counter in many countries, with guidance to limit use to short periods and to consult a healthcare professional if symptoms persist. Related decongestants include tetrahydrozoline and oxymetazoline.