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.

A few warnings and contraindications that apply to all naphazoline-containing substances intended for medicinal use are: Known side-effect:[5][6] Naphazoline is a mixed α1- and α2-adrenergic receptor agonist.

[2] The non-hydrochloride form of Naphazoline has the molecular formula C14H14N2 and a molar mass of 210.28 g/mol.

[7] The nasal or ophthalmic form of naphazoline has been abused by heroin or cocaine drug addicts.