Clinical data
Trade namesClear Eyes, Cleari, Naphcon-A, Rohto
Routes of
Ophthalmic drug administration, nasal administration
ATC code
Legal status
Legal status
  • 2-(naphthalen-1-ylmethyl)-4,5-dihydro-1H-imidazole
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.011.492 Edit this at Wikidata
Chemical and physical data
Molar mass210.280 g·mol−1
3D model (JSmol)
  • N\1=C(\NCC/1)Cc2cccc3c2cccc3
  • InChI=1S/C14H14N2/c1-2-7-13-11(4-1)5-3-6-12(13)10-14-15-8-9-16-14/h1-7H,8-10H2,(H,15,16) checkY
 ☒NcheckY (what is this?)  (verify)

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.[1]

Medical uses

Red eyes can be treated with naphazoline.

Nasal administration

Nasal decongestant.[2]

Ophthalmic drug administration

Eye drops (brand names Clear Eyes, and Cleari) narrowing swollen blood vessels (ophthalmic arteries, and ophthalmic veins) to relieve red eye.[2]

Temporary red eye can safely be treated when the cause of the redness is established (e.g. cannabis induced corneal vasodilation)[3]. However, continuous use is not recommended without knowing an underlying condition.

Side effects

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

Nasal administration

Ophthalmic drug administration

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. The HCl salt form has a molar mass of 246.73 g/mol.

Society and culture

It is an active ingredient in several over-the-counter eye drop formulations including Clear Eyes, Rohto, Eucool, and Naphcon-A.[7]

Illicit use

The nasal or ophthalmic form of naphazoline has been abused by heroin or cocaine drug addicts.[8][9] It's used as CNS stimulant and vasoconstrictor to enhance primary drug effects.[9]


  1. ^ Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 552. ISBN 9783527607495.
  2. ^ a b c Hosten LO, Snyder C (2020). "Over-the-Counter Ocular Decongestants in the United States - Mechanisms of Action and Clinical Utility for Management of Ocular Redness". Clinical Optometry. 12: 95–105. doi:10.2147/OPTO.S259398. PMC 7399465. PMID 32801982.
  3. ^ Yazulla S (September 2008). "Endocannabinoids in the retina: from marijuana to neuroprotection". Progress in Retinal and Eye Research. 27 (5): 501–526. doi:10.1016/j.preteyeres.2008.07.002. PMC 2584875. PMID 18725316.
  4. ^ Zavala JA, Pereira ER, Zétola VH, Teive HA, Nóvak EM, Werneck LC (September 2004). "Hemorrhagic stroke after naphazoline exposition: case report". Arquivos de Neuro-Psiquiatria. 62 (3B): 889–891. doi:10.1590/S0004-282X2004000500030. PMID 15476091.
  5. ^ "Naphazoline - FDA prescribing information, side effects and uses".
  6. ^ "naphazoline ophthalmic (eye): Uses, Side Effects, Interactions, Pictures, Warnings & Dosing - WebMD".
  7. ^ Green SM (2008). "Ophthalmology: Naphazoline". Tarascon Pocket Pharmacopoeia 2009. Jones and Bartlett. ISBN 978-0-7637-6572-9.
  8. ^ van Montfrans GA, van Steenwijk RP, Vyth A, Borst C (1981). "Intravenous naphazoline intoxication". Acta Medica Scandinavica. 209 (5): 429–430. doi:10.1111/j.0954-6820.1981.tb11622.x. PMID 7246278.
  9. ^ a b "Naphazoline abuse". Reactions Weekly. 1815 (1): 251. 2020-08-01. doi:10.1007/s40278-020-81577-1. ISSN 1179-2051. S2CID 195174995.