Tetrahydrozolin

Tetrahydrozoline, often encountered as tetrahydrozoline hydrochloride in medicinal products, is a sympathomimetic vasoconstrictor used in ophthalmic and nasal preparations to relieve redness and congestion. It acts as an agonist at alpha-adrenergic receptors, producing constriction of blood vessels in the conjunctiva or nasal mucosa.

In ophthalmology, tetrahydrozoline is formulated as eye drops or ointments to reduce redness caused by minor irritation or dryness. It temporarily narrows superficial ocular vessels, providing symptomatic relief. In nasal preparations, it serves as a vasoconstrictor to shrink swollen nasal mucosa and ease nasal congestion, typically as a short-term remedy.

Use is generally limited to brief periods, as prolonged or repeated use can lead to rebound congestion (rhinitis medicamentosa) or tolerance, reducing effectiveness. It can cause systemic effects if absorbed in significant amounts, including tachycardia, hypertension, anxiety, and headache, though these are uncommon with proper topical use. Local adverse effects may include burning, stinging, or irritation at the site of administration. Cautions include avoiding use in individuals with uncontrolled hypertension, ischemic heart disease, certain types of glaucoma, or hypersensitivity to the drug. Pediatric use is often restricted and should follow product labeling and medical advice.

Regulatory status varies by country; tetrahydrozoline is available in over-the-counter formulations for short-term relief in many regions, with warnings to limit duration of use and to seek medical guidance for symptoms persisting beyond a few days.