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Trade namesRohto Relief, Visine Original, others[1]
Other namesTetrahydrozoline[1]
  • (RS)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)-4,5-dihydro-1H-imidazole
Clinical data
Main usesSwelling of the whites of the eyes[1]
Side effectsDilated pupils, blurry vision, irritation of the eyes[1]
Onset of actionWithin minutes[1]
Duration of actionUp to 8 hrs[1]
External links
Chemical and physical data
Molar mass200.285 g·mol−1
3D model (JSmol)
Melting point117–119 °C (243–246 °F) [2] 256–257 °C (493–495 °F) for HCl-salt[3]
Solubility in waterVery soluble in water and ethanol, slightly soluble in chloroform and insoluble in diethylether[3] mg/mL (20 °C)
  • N\1=C(\NCC/1)C3c2ccccc2CCC3
  • InChI=1S/C13H16N2/c1-2-6-11-10(4-1)5-3-7-12(11)13-14-8-9-15-13/h1-2,4,6,12H,3,5,7-9H2,(H,14,15) checkY

Tetryzoline, also known as tetrahydrozoline, is a medication used to improve swelling of the whites of the eyes.[1] It is available alone and in combination as an over-the-counter eye drop.[1] Effects begin within minutes and may last for up to 8 hours.[1] Long term use may worsen the condition.[1]

Common side effects include dilated pupils, blurry vision, and irritation of the eyes.[1] Other side effects may include redness of the eyes, headache, palpitations, and trouble sleeping.[1] It works by causing blood vessels to contract by activation α-adrenergic receptors.[1]

Tetryzoline was patented in 1954 and came into medical use in 1959.[4] In the United States a bottle costs about 10 USD as of 2021.[5] It is sold under many brand names including Visine and Rohto.[1]

Side effects

Tetryzoline eye drops may cause blurred vision, eye irritation and dilated pupils.[6] Tetryzoline is not suitable for prolonged use as its vasoconstrictive effects within the eye eventually decrease or stop. If tolerance to the drug has developed, ceasing its use may cause a rebound effect and increase redness of the eyes — ⁠a vasodilatory effect.[7]

Intranasal use of tetryzoline may cause transient burning, stinging, or dryness of the mucosa and sneezing. Prolonged intranasal use often causes opposite effects in the form of rebound congestion with effects such as chronic redness, swelling and rhinitis. Prolonged use thus may result in overuse of the drug.[6]

Overdose most often causes slow heart rate. Respiratory depression, low blood pressure, constricted pupils, hypothermia, brief episodes of high blood pressure,[8] drowsiness, headaches and vomiting may also occur.[9] In serious cases some of these effects may result in circulatory shock.[6] Most often overdoses occur in children who have ingested the drug.[8]

There is no antidote for tetryzoline or other similar imidazoline analogue poisoning, but the symptoms can be alleviated and with treatment, death is rare.[10]

Mechanism of action

Tetryzoline is an alpha agonist for alpha-2 receptor and imidazoline receptor I-1 agonist. Mainly due to its alpha-2 agonism it can constrict conjuctival blood vessels of the eye when taken in the form of eye drops.[11] This relieves the redness of the eye caused by minor ocular irritants. To treat allergic conjunctivitis, tetryzoline can be combined in a solution with antazoline.[12]

In an overdose, slow heart rate and low blood pressure are mainly due to imidazoline-1 receptor agonism. Dry mouth and sedating effects are due to alpha-2 agonism.[11]


The half-life of tetryzoline in healthy people is about 6 hours and it is excreted unchanged in urine, at least in part. In one study 10 people were given two drops of 0.5 mg/ml tetryzoline eye drops (0.025–0.05 mg) at 0, 4, 8 and 12 h. Within a 24 h time window since the last dose, tetryzoline blood serum concentration of the subjects was 13.0–210.0 ng/ml and urine concentration was 11–400 ng/ml. Both reached their maximum about 9 h post last dose. These levels correspond to normal ocular use of tetryzoline. Higher concentrations may indicate misuse of the drug or poisoning.[10]


Chemically, tetryzoline is a derivative of imidazoline. It has two enantiomers.

Society and culture


Tetryzoline is the INN.[13]

Urban legend

An urban legend suggests that tetryzoline can cause violent diarrhea if given orally, such as by putting a few drops of Visine in an unsuspecting person's beverage. However, the actual results of the prank may be worse, varying from severe nausea and vomiting to seizures or a coma. Diarrhea is not a side effect.[14]

Criminal use

In late August 2018, a South Carolina woman was charged with murdering her husband by putting eye drops containing tetryzoline in his drinking water. An autopsy found high concentrations of tetryzoline in his body.[15][16][17]

Tetryzoline has been used as a date rape drug in a number of cases due to its ability to cause dizziness and unconsciousness.[9]

In 2018 an elderly woman in Pewaukee, Wisconsin died in an apparent overdose or suicide, and years later police charged her caregiver with murder, alleging that the death was caused by a water bottle laced with Visine.[18]


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 "Tetrahydrozoline Monograph for Professionals". Drugs.com. Archived from the original on 22 January 2021. Retrieved 3 October 2021.
  2. "US 2731471 A - IP.com". ip.com. Archived from the original on 2021-08-29. Retrieved 2018-09-05.
  3. 3.0 3.1 The Merck index. Chapman & Hall Electronic Publishing Division (12th ed.). Whitehouse Station, NJ, United States: Chapman & Hall Electronic Pub. Division. 2000. p. 1453. ISBN 1584881291. OCLC 46987702.{{cite book}}: CS1 maint: others (link)
  4. Fischer, Jnos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 552. ISBN 9783527607495. Archived from the original on 2016-12-29. Retrieved 2021-06-09.
  5. "Tetrahydrozoline ophthalmic Prices, Coupons & Patient Assistance Programs". Drugs.com. Archived from the original on 15 April 2021. Retrieved 3 October 2021.
  6. 6.0 6.1 6.2 "Tetrahydrozoline". toxnet.nlm.nih.gov. Archived from the original on 2017-01-03. Retrieved 2018-09-05.
  7. McLaurin E, Cavet ME, Gomes PJ, Ciolino JB (March 2018). "Brimonidine Ophthalmic Solution 0.025% for Reduction of Ocular Redness: A Randomized Clinical Trial". Optometry and Vision Science. 95 (3): 264–271. doi:10.1097/OPX.0000000000001182. PMC 5839712. PMID 29461408.
  8. 8.0 8.1 Al-Abri SA, Yang HS, Olson KR (December 2014). "Unintentional pediatric ophthalmic tetrahydrozoline ingestion: case files of the medical toxicology fellowship at the University of California, San Francisco". Journal of Medical Toxicology. 10 (4): 388–91. doi:10.1007/s13181-014-0400-9. PMC 4252297. PMID 24760708.
  9. 9.0 9.1 Stillwell ME, Saady JJ (September 2012). "Use of tetrahydrozoline for chemical submission". Forensic Science International. 221 (1–3): e12-6. doi:10.1016/j.forsciint.2012.04.004. PMID 22554870.
  10. 10.0 10.1 Carr ME, Engebretsen KM, Ho B, Anderson CP (November 2011). "Tetrahydrozoline (Visine®) concentrations in serum and urine during therapeutic ocular dosing: a necessary first step in determining an overdose". Clinical Toxicology. 49 (9): 810–4. doi:10.3109/15563650.2011.615064. PMID 21972870. S2CID 20238499.
  11. 11.0 11.1 Lowry JA, Brown JT (June 2014). "Significance of the imidazoline receptors in toxicology". Clinical Toxicology. 52 (5): 454–69. doi:10.3109/15563650.2014.898770. PMID 24666288. S2CID 2231590.
  12. Castillo M, Scott NW, Mustafa MZ, Mustafa MS, Azuara-Blanco A (June 2015). "Topical antihistamines and mast cell stabilisers for treating seasonal and perennial allergic conjunctivitis" (PDF). The Cochrane Database of Systematic Reviews. 6 (6): CD009566. doi:10.1002/14651858.CD009566.pub2. hdl:2164/6048. PMID 26028608. Archived from the original on 2021-08-28. Retrieved 2021-06-09.
  13. "International Non-Proprietary Names for Pharmaceutical Preparations. Recommended International Non-Proprietary Names: List 3" (PDF). World Health Organization. p. 474. Archived (PDF) from the original on 2016-09-11. Retrieved 30 August 2016.
  14. "Visine Prank: Mickey Red Eyes". Snopes. 29 June 2009. Archived from the original on 29 August 2021. Retrieved 28 July 2010.
  15. "US wife accused of 'fatally poisoning husband with eyedrops'". BBC. 4 September 2018. Archived from the original on 5 September 2018. Retrieved 4 September 2018.
  16. Police: Woman kills husband by putting eye drops in water, Associated Press, Aug 31, 2018, archived from the original on September 2, 2018, retrieved June 9, 2021
  17. Connelly E (1 September 2018). "Wife admits fatally poisoning 'unfaithful' hubby with eye drops: cops" (Newspaper). New York Post. Archived from the original on 2018-09-02. Retrieved 3 September 2018.
  18. Wisconsin woman arrested, accused of murdering friend with eye drops: An investigation alleges the victim's water bottle was laced with Visine. Archived 2021-06-09 at the Wayback Machine ABC News, Bill Hutchinson, June 8, 2021

External links