Naphazoline is a medicine used as a decongestant, and a vasoconstrictor added to eye drops to relieve red eye. It has a rapid action in reducing swelling when applied to mucous membranes. It is a sympathomimetic agent with marked alpha adrenergic activity that acts on alpha-receptors in the arterioles of the conjunctiva to produce constriction, resulting in decreased congestion.

It was patented in 1934 and came into medical use in 1942.

Nasal decongestant.

Eye drops (brand names Clear Eyes, and Cleari) narrowing swollen blood vessels (ophthalmic arteries, and ophthalmic veins) to relieve red eye.

Temporary red eye can safely be treated when the cause of the redness is established (e.g. cannabis induced conjunctival vasodilation). However, continuous use is not recommended without knowing an underlying condition.

A few warnings and contraindications that apply to all naphazoline-containing substances intended for medicinal use are:

Known side-effect:

Naphazoline is a mixed α₁- and α₂-adrenergic receptor agonist.