(fen il EF rin)

U.S. Brand Names

AK-Dilate®; AK-Nefrin®; Formulation R™ [OTC]; Medicone® [OTC]; Mydfrin®; Neo-Synephrine® Extra Strength [OTC]; Neo-Synephrine® Mild [OTC]; Neo-Synephrine® Ophthalmic; Neo-Synephrine® Regular Strength [OTC]; Nostril® [OTC]; Phenoptic®; Prefrin™ [DSC]; Relief® [OTC]; Vicks® Sinex® Nasal Spray [OTC]; Vicks® Sinex® UltraFine Mist [OTC]


Phenylephrine Hydrochloride

Generic Available

Yes: Excludes nasal drops and spray

Canadian Brand Names

Dionephrine®; Mydfrin®; Neo-Synephrine®


Treatment of hypotension, vascular failure in shock; as a vasoconstrictor in regional analgesia; as a mydriatic in ophthalmic procedures and treatment of wide-angle glaucoma; supraventricular tachycardia

For OTC use as symptomatic relief of nasal and nasopharyngeal mucosal congestion, treatment of hemorrhoids, relief of redness of the eye due to irritation

Pregnancy Risk Factor



Enters breast milk/not recommended


Hypersensitivity to phenylephrine, bisulfite (some products contain metabisulfite), or any component of the formulation; hypertension; ventricular tachycardia


Use with caution in the elderly, patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease, or severe CAD. Not a substitute for volume replacement. Avoid hypertension; monitor blood pressure closely and adjust infusion rate. Infuse into a large vein if possible. Watch I.V. site closely. Avoid extravasation. With intranasal formulation use, rebound congestion can occur when the drug is discontinued after chronic use.

Adverse Reactions

Frequency not defined.

Cardiovascular: Reflex bradycardia, excitability, restlessness, arrhythmia (rare), precordial pain or discomfort, pallor, hypertension, severe peripheral and visceral vasoconstriction, decreased cardiac output

Central nervous system: Headache, anxiety, dizziness, tremor, paresthesia, restlessness

Endocrine & metabolic: Metabolic acidosis

Local: I.V.: Extravasation which may lead to necrosis and sloughing of surrounding tissue, blanching of skin

Neuromuscular & skeletal: Pilomotor response, weakness

Renal: Decreased renal perfusion, reduced urine output

Respiratory: Respiratory distress


Symptoms of overdose include vomiting, hypertension, palpitations, paresthesia, and ventricular extrasystoles. Treatment is supportive. In extreme cases, I.V. phentolamine may be used.

Drug Interactions

Beta-blockers (nonselective ones) may increase hypertensive effect; avoid concurrent use.

Cocaine may cause malignant arrhythmias; avoid concurrent use.

Guanethidine can increase the pressor response; be aware of the patient's drug regimen.

MAO inhibitors potentiate hypertension and hypertensive crisis; avoid concurrent use.

Methyldopa can increase the pressor response; be aware of patient's drug regimen.

Phenytoin administration during a dopamine infusion may result in hypotension and possibly cardiac arrest; use cautiously.

Reserpine increases the pressor response; be aware of patient's drug regimen.

TCAs increase the pressor response; be aware of patient's drug regimen.

Ethanol/Nutrition/Herb Interactions

Herb/Nutraceutical: Avoid ephedra, yohimbe (may cause CNS stimulation).


Solution for injection: Store vials at controlled room temperature of 15°C to 30°C (59°F to 86°F); protect from light. Do not use solution if brown or contains a precipitate.

I.V. infusion: May dilute 10 mg in 500 mL NS or D5W.

I.V. injection: Dilute with SWFI to a concentration of 1 mg/mL.

Ophthalmic solution: Store at controlled room temperature; protect from light and excessive heat


Stable in dextran 6% in dextrose, dextran 6% in NS, D5LR, D5/4NS, D5/2NS, D5NS, D5W, D10W, LR, /2NS, NS, sodium bicarbonate 5%


Y-site administration: Compatible: Amiodarone, cisatracurium, etomidate, famotidine, haloperidol, inamrinone, levofloxacin, remifentanil, zidovudine. Incompatible: Thiopental. Variable (consult detailed reference): Propofol

Compatibility when admixed: Compatible: Chloramphenicol, chloramphenicol with sodium bicarbonate, dobutamine, lidocaine, potassium chloride, sodium bicarbonate

Mechanism of Action

Potent, direct-acting alpha-adrenergic stimulator with weak beta-adrenergic activity; causes vasoconstriction of the arterioles of the nasal mucosa and conjunctiva; activates the dilator muscle of the pupil to cause contraction; produces vasoconstriction of arterioles in the body; produces systemic arterial vasoconstriction


Onset of action: I.M., SubQ: 10-15 minutes; I.V.: Immediate

Duration: I.M.: 0.5-2 hours; I.V.: 15-30 minutes; SubQ: 1 hour

Metabolism: Hepatic, via intestinal monoamine oxidase to phenolic conjugates

Half-life elimination: 2.5 hours; prolonged after long-term infusion

Excretion: Urine (90%)


Ocular procedures:

Infants <1 year: Instill 1 drop of 2.5% 15-30 minutes before procedures

Children and Adults: Instill 1 drop of 2.5% or 10% solution, may repeat in 10-60 minutes as needed

Ophthalmic irritation (OTC formulation for relief of eye redness): Adults: Instill 1-2 drops 0.12% solution into affected eye, up to 4 times/day; do not use for >72 hours

Nasal decongestant (therapy should not exceed 3 continuous days):


2-6 years: Instill 1 drop every 2-4 hours of 0.125% solution as needed

6-12 years: Instill 1-2 sprays or instill 1-2 drops every 4 hours of 0.25% solution as needed

Children >12 years and Adults: Instill 1-2 sprays or instill 1-2 drops every 4 hours of 0.25% to 0.5% solution as needed; 1% solution may be used in adult in cases of extreme nasal congestion; do not use nasal solutions more than 3 days



I.M., SubQ: 0.1 mg/kg/dose every 1-2 hours as needed (maximum: 5 mg)

I.V. bolus: 5-20 mcg/kg/dose every 10-15 minutes as needed

I.V. infusion: 0.1-0.5 mcg/kg/minute


I.M., SubQ: 2-5 mg/dose every 1-2 hours as needed (initial dose should not exceed 5 mg)

I.V. bolus: 0.1-0.5 mg/dose every 10-15 minutes as needed (initial dose should not exceed 0.5 mg)

I.V. infusion: 10 mg in 250 mL D5W or NS (1:25,000 dilution) (40 mcg/mL); start at 100-180 mcg/minute (2-5 mL/minute; 50-90 drops/minute) initially; when blood pressure is stabilized, maintenance rate: 40-60 mcg/minute (20-30 drops/minute); rates up to 360 mcg/minute have been reported; dosing range: 0.4-9.1 mcg/kg/minute

Note: Concentrations up to 100-500 mg in 250 mL have been used.

Paroxysmal supraventricular tachycardia: I.V.:

Children: 5-10 mcg/kg/dose over 20-30 seconds

Adults: 0.25-0.5 mg/dose over 20-30 seconds

Hemorrhoids: Children

12 years and Adults: Rectal:

Cream/ointment: Apply to clean dry area, up to 4 times/day; may be used externally or inserted rectally using applicator.

Suppository: Insert 1 suppository rectally, up to 4 times/day


Concentration and rate of infusion can be calculated using the following formulas: Dilute 0.6 mg x weight (kg) to 100 mL; then the dose in mcg/kg/minute = 0.1 x the infusion rate in mL/hour

May cause necrosis or sloughing tissue if extravasation occurs during I.V. administration or SubQ administration.

Extravasation management: Use phentolamine as antidote; mix 5 mg with 9 mL of NS. Inject a small amount of this dilution into extravasated area. Blanching should reverse immediately. Monitor site. If blanching should recur, additional injections of phentolamine may be needed.

Monitoring Parameters

Blood pressure, heart rate, arterial blood gases, central venous pressure

Patient Education

Nasal decongestant: Do not use for more than 3 days in a row. Clear nose as much as possible before use. Tilt head back and instill recommended dose of drops or spray. Do not blow nose for 5-10 minutes. You may experience transient stinging or burning.

Ophthalmic: Do not let tip of applicator touch eye; do not contaminate tip of applicator (may cause eye infection, eye damage, or vision loss). Open eye, look at ceiling, and instill prescribed amount of solution. Close eye and roll eye in all directions, and apply gentle pressure to inner corner of eye for 1-2 minutes after instillation. Temporary stinging or blurred vision may occur. Report persistent pain, burning, double vision, severe headache, or if condition worsens.

Pregnancy/breast-feeding precautions: Inform prescriber if you are pregnant. Consult prescriber if breast-feeding.

Additional Information

Phenylephrine allows for close titration of blood pressure and should be used in patients with hypotension or shock due to peripheral vasodilation. Phenylephrine should not constitute sole therapy in patients with hypotension due to aortic dysfunction or hypovolemia. An important benefit of this drug is the short half-life, allowing rapid changes in dosage with prompt appropriate blood pressure responses. When administered intravenously, it should be used in intensive care settings or under very close monitoring.

Anesthesia and Critical Care Concerns/Other Considerations

Phenylephrine allows for close titration of blood pressure and may be used in patients with hypotension or shock due to peripheral vasodilation; can increase blood pressure in fluid-resuscitated septic shock patients; does not impair cardiac or renal function. May be a good choice when tachyarrhythmias limit use of other vasopressors, although experience in patients with septic shock is limited. An increase in oxygen delivery and consumption may occur in >15% of patients according to one study (Flancbaum, 1997).

Extravasation Management: Antidote for peripheral ischemia caused by phenylephrine extravasation: To prevent sloughing and necrosis in ischemic areas, the area should be infiltrated as soon as possible with 5-10 mg of Regitine® (phentolamine), an adrenergic blocking agent, diluted in 10-15 mL of saline. A syringe with a fine hypodermic needle should be used, and the solution liberally infiltrated throughout the ischemic area. Sympathetic blockade with phentolamine causes immediate and conspicuous local hyperemic changes if the area is infiltrated within 12 hours. Therefore, phentolamine should be given as soon as possible after the extravasation is noted, as phentolamine may be ineffective if given >12 hours after extravasation.

Cardiovascular Considerations

Phenylephrine allows for close titration of blood pressure and should be used in patients with hypotension or shock due to peripheral vasodilation. Phenylephrine should not constitute sole therapy in patients with hypotension due to aortic dysfunction or hypovolemia. An important benefit of this drug is the short half-life, allowing rapid changes in dosage with prompt appropriate blood pressure responses. When administered intravenously, it should be used in intensive care settings or under very close monitoring.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Tachycardia, palpitations (use vasoconstrictor with caution), and xerostomia (normal salivary flow resumes upon discontinuation).

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

Use with caution since phenylephrine is a sympathomimetic amine which could interact with epinephrine to cause a pressor response

Mental Health: Effects on Mental Status

May cause anxiety or restlessness

Mental Health: Effects on Psychiatric Treatment

Concurrent use with MAO inhibitors may result in hypertensive crisis; avoid combination

Dosage Forms

[DSC] = Discontinued product

Cream, rectal (Formulation R™): 0.25% (30 g, 60 g) [contains sodium benzoate]

Injection, solution, as hydrochloride: 1% [10 mg/mL] (1 mL) [may contain sodium metabisulfite]

Ointment, rectal (Formulation R™): 0.25% (30 g, 60 g) [contains benzoic acid]

Solution, intranasal drops, as hydrochloride:

Neo-Synephrine® Extra Strength: 1% (15 mL)

Neo-Synephrine® Regular Strength: 0.5% (15 mL)

Solution, intranasal spray, as hydrochloride:

Neo-Synephrine® Extra Strength: 1% (15 mL)

Neo-Synephrine® Mild: 0.25% (15 mL)

Neo-Synephrine® Regular Strength: 0.5% (15 mL)

Nostril®: 0.25% (15 mL); 0.5% (15 mL)

Vicks® Sinex®, Vicks® Sinex® UltraFine Mist: 0.5% (15 mL)

Solution, ophthalmic, as hydrochloride: 2.5% (2 mL, 3 mL, 5 mL, 15 mL) [may contain sodium bisulfite]

AK-Dilate®: 2.5% (2 mL, 15 mL); 10% (5 mL)

AK-Nefrin®: 0.12% (15 mL)

Mydfrin®: 2.5% (3 mL, 5 mL) [contains sodium bisulfite]

Neo-Synephrine®: 2.5% (15 mL); 10% (5 mL)

Neo-Synephrine® Viscous: 10% (5 mL)

Phenoptic®: 2.5% (15 mL)

Prefrin™ [DSC], Relief®: 0.12% (15 mL)

Suppository, rectal: 0.25% (12s)

Medicone®: 0.25% (18s, 24s)


Bonfiglio MF, Dasta JF, Gregory JS, et al, "High-Dose Phenylephrine Infusion in the Hemodynamic Support of Septic Shock,"DICP, 1990, 24(10):936-9.

Flancbaum L, Dick M, Dasta J, et al, "A Dose-Response Study of Phenylephrine in Critically Ill, Septic Surgical Patients,"Eur J Clin Pharmacol, 1997, 51(6):461-5.

Gregory JS, Bonfiglio MF, Dasta JF, et al, "Experience With Phenylephrine as a Component of the Pharmacologic Support of Septic Shock,"Crit Care Med, 1991, 19(11):1395-400.

International Brand Names

Ada® (ES); AF-TAF® (IL); Analux® (ES, HK, HU, PL); Boradrine® (BE, NL); Boraline® (CY, EG, ES, JO, KW, LB, SY); Chlorhydrate de phenylephrine® (LU); Colircusi Fenilefrina® (ES); Dionephrine® (CA); Disneumon® (ES); Efrin® (IL); Efrisel® (ID); Fadalefrina® (AR); Fenilefrina® (BR); Fenilefrina Cloridrato® (IT); Fenilefrina Gray® (AR); Fenilefrin® (BR, TR); Fenox® (HK); Fenylefrine Minims® (NL); Fenylefrine Monofree® (NL); Isonefrine® (IT); Isopto Frin® (AU, CZ, GB, HK, IE, LU, SG); Isoptorfrin® (RO); Isotic Frizin® (ID); Metaoxedrin Minims® (NO); Metaoxedrin Ophtha® (DK); Metaoxedrin SAD® (DK); Minims Phenylephrine® (AT, BE, IE); Minims Phenylephrine Hydrochloride® (AT, FI, GB, NZ, SG, ZA); Minims-Phenylephrin-Hydrochlorid® (AT); Mirazul® (ES); Moviflex® (AT); Mydfrin® (AR, CA, CL, HK); Myd Frin® (RO); Mydfrin® (SG, TR, ZA); Nasenspray Spirig für Kinder® (CH); Neo-Mydrial® (DE); Neo-Sinefrina® (BR, PT); Neo-Synephrine® (AU, CA, CY, CZ, EG, IL, IT, JO, KW, LB); Néosynéphrine Chibret® (FR); Néosynéphrine Faure® (FR); Neosynephrine® (LU); Neo-Synephrine® (NZ, PL, RO); Neosynephrin-POS® (DE); Non Drowsy Sudafed Congestion Relief® (GB); Nyal Decongestant® (AU); Oftan Metaoksedrin® (FI); Otriven Baby® (DE); Phenylephrin "Blache"® (CH); Phenylephrine® (BE, GB); Phenylephrine Bournonville® (LU); Phenylephrine Covan® (ZA); Phenylephrine Hydrochloride® (SE); Poen Efrina® (AR); Prefrin® (AR, AU, HK, NZ); Pupiletto® (IN); Rexophtal® (CH); Rhinofluine® (BE); Rhinopront® (AT); Ribex Nasale® (IT); Rin Up® (ES); Visadron® (AT, BE, CY, DE, EG, ES, IT, JO, KW, LB, LU, MT, NL, PT); Visopt Eye Drops® (AU); Vistafrin® (ES)

Review Date: 1969-12-31 Reviewed By: Keywords: ,
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