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Phenylephrine Hydrochloride

Pronunciation: FEN-il-EF-rin HYE-droe-KLOR-ide
Class: Arylalkylamines, Decongestant, Ophthalmic decongestant, Vasopressor used in shock

Trade Names

- Solution, ophthalmic 2.5%
- Solution, ophthalmic 10%

- Liquid, oral 7.5 mg per 5 mL

Mydfrin 2.5%
- Solution, ophthalmic 2.5%

- Solution, intranasal 0.25%
- Solution, intranasal 0.5%
- Solution, intranasal 1%
- Injection 1% (10 mg/mL)

- Solution, ophthalmic 2.5%

- Solution, intranasal 0.25%

Sudogest PE
- Tablets 10 mg

Vicks Sinex
- Solution, intranasal 0.5%

Sudafed PE Decongestant (Canada)


Stimulates postsynaptic alpha receptors, resulting in rise in intense arterial peripheral vasoconstriction. Causes marked increase in systolic, diastolic, and pulmonary pressures, as well as reflex bradycardia. Slightly decreases cardiac output and increases coronary blood flow.



In liver and GI.


Rapid (IV).


20 min (IV); 50 min (subcutaneous).

Indications and Usage

Temporary relief of nasal congestion and pressure, and of minor eye irritations; pupil dilation in uveitis; treatment of open-angle glaucoma; use in diagnostic procedures (funduscopy) and before surgery; use in many ophthalmic surgeries; refraction without cycloplegia.


Treatment of vascular failure in shock, shock-like states, drug-induced hypotension or hypersensitivity; correction of paroxysmal supraventricular tachycardia; prolongation of spinal anesthesia; vasoconstriction in regional analgesia; maintenance of adequate level of BP during spinal and inhalation anesthesia.

Unlabeled Uses

Management of drug-induced distributive shock.


Hypersensitivity to any component of the products, potassium guaiacolsulfonate, or to sympathomimetic amines; severe hypertension; ventricular tachycardia; pheochromocytoma; ophthalmic 10% solution contraindicated in infants and patients with aneurysms; low birth weight infants; anatomically narrow angles or narrow-angle glaucoma; during intraocular procedures when the corneal epithelial barrier has been disrupted; elderly patients with severe arteriosclerotic CV or cerebrovascular disease; MAOI use or 14 days after stopping an MAOI; severe coronary artery disease.

Dosage and Administration

Mild or Moderate Hypotension

Subcutaneous / IM 1 to 10 mg (usually 2 to 5 mg); do not exceed initial dose of 5 mg. Avoid repeat injections more often than every 10 to 15 min. IV 0.1 to 0.5 mg (usually 0.2 mg); do not exceed initial dose of 0.5 mg. Avoid repeat injections more often than every 10 to 15 min.

Severe Hypotension and Shock

IV continuous infusion For initial dose, give 100 to 180 mcg/min of 1:50,000 solution (10 mg per 500 mL of dextrose injection or sodium chloride); once BP has stabilized to low normal level, decrease to maintenance rate of 40 to 60 mcg/min. If prompt initial vasopressor response is not obtained, increase dosage in increments greater than or equal to 10 mg and add to infusion; adjust rate until desired BP is obtained.

Hypotension of Spinal Anesthesia

Subcutaneous / IM 2 to 3 mg three to four min before injection of anesthetic. IV For hypotensive emergencies during spinal anesthesia, inject 0.2 mg, increasing by no more than 0.1 to 0.2 mg/dose (max, 0.5 mg/dose).


Subcutaneous / IM 0.5 to 1 mg per 25 lb.

Prolongation of Spinal Anesthesia

2 to 5 mg added to anesthetic solution increases duration of motor block by up to 50%.

Vasoconstriction for Regional Analgesia

At least 2 mg added to local anesthetic solution in concentration of 1:20,000 (1 mg of phenylephrine per 20 mL of anesthetic solution).

Paroxysmal Supraventricular Tachycardia


Initial dose

0.5 mg or less via rapid IV push (within 20 to 30 sec); subsequent doses should not exceed preceding dose by more than 0.1 to 0.2 mg (max, 1 mg/dose).

Nasal Congestion
Adults and Children 12 y of age and older

Intranasal 1 to 2 sprays or 3 drops of 0.25%, 0.5%, or 1% solution every 4 h. Oral 10 to 15 mg every 4 to 6 h, up to 60 mg/day.

Children 6 to 12 y of age

Intranasal 2 to 3 sprays of 0.25% solution in each nostril every 3 to 4 h. Oral 7.5 mg every 4 to 6 h, up to 30 mg/day.

Children 2 to 6 y of age

Oral 3.75 mg every 4 to 6 h, up to 15 mg/day.

Children 6 mo to 6 y of age

Intranasal 1 to 2 drops of 0.16% solution in each nostril every 3 h.

Vasoconstriction/Pupil Dilation

Ophthalmic Instill 1 drop of 2.5% or 10% on upper limbus. If necessary, repeat after 1 h.

Uveitis/Prevention of Synechiae

Ophthalmic Instill 2.5% or 10% phenylephrine to the upper surface of the cornea and repeat as necessary, not to exceed 3 times. May continue treatment the following day if necessary. Use with atropine and hot compresses.

Wide-Angle Glaucoma

Ophthalmic Instill 1 drop of 10% on upper surface of cornea as needed.

Open-Angle Glaucoma

Ophthalmic Instill 1 drop of 2.5% solution in conjunction with miotics.

Intraocular Surgery

Ophthalmic Instill 1 drop of 2.5% or 10% solution 30 to 60 min before operation.


Ophthalmic Instill 1 drop of 2.5% solution in conjunction with cycloplegics.


Ophthalmic Instill 1 drop of 2.5% solution in conjunction with cycloplegics.

Ophthalmoscopic Examination

Ophthalmic Instill 1 drop of 2.5% solution in each eye. Dilation lasts from 1 to 3 h.

Diagnostic Procedures/Provocative Test for Angle-Block in Glaucoma

Ophthalmic Instill 2.5% solution.


Ophthalmic Instill 2.5% solution.

Blanching Test

Ophthalmic Instill 1 to 2 drops of 2.5% solution to the injected eye. After 5 min, examine for perilimbal blanching. If blanching occurs, congestion is superficial and probably does not indicate iridocyclitis.

Minor Eye Irritations

Ophthalmic Instill 1 to 2 drops of 0.12% solution up to 4 times daily.

General Advice

  • Injection
  • For vasopressor use, administer medication via continuous pump infusion. Administer IV through large vein, preferably central vein. Titrate carefully to avoid hypotension.
  • For subcutaneous, IM, slow IV, or diluted as a continuous infusion.
  • For 10 mg dose, use 1 mL; 5 mg dose, use 0.5 mL; 1 mg dose, use 0.1 mL.
  • For intermittent IV, dilute 1 mL in 9 mL of sterile water for injection to yield a phenylephrine 0.1% solution. For 0.1 mg, use 0.1 mL of dilute solution; for 0.2 mg, use 0.2 mL of dilute solution; for 0.5 mg, use 0.5 mL of dilute solution.
  • Intranasal
  • With intranasal administration, do not share container. Instill spray into nose with head upright. Have patient sniff hard for a few minutes after administration. To instill drops, have patient recline on bed, hang head over edge, and instill drops. Have patient remain in this position for several minutes after using and turn head from side to side. Do not allow tip of container to touch nasal passage. Discard after medication is no longer needed.
  • Ophthalmic
  • To instill ophthalmic solution, tilt patient's head back, hold dropper over eye, drop medication inside lower lid, and apply pressure to inside corner of eye for 2 to 3 min. Take care not to touch dropper to eye.
  • Prolonged exposure of ophthalmic solution to air or strong light may cause oxidation and discoloration. Do not use if solution is discolored or cloudy or contains precipitate.
  • Heavily pigmented irides may require larger doses.


Store at 68° to 77°F and protect from light and excessive heat.

Drug Interactions


Concurrent use may enhance the pressor effects and induce tachycardia, especially in infants.


Decrease phenylephrine's effect.

Digitalis glycosides, general anesthetics


Furazolidone, MAOIs

May significantly increase pressor response resulting in hypertensive crisis and intracranial hemorrhage.

Guanethidine, methyldopa, reserpine

May increase pressor response of phenylephrine; resulting in severe hypertension.

Halogenated hydrocarbon anesthetics

May sensitize myocardium to effects of catecholamines. Use extreme caution to avoid arrhythmias.

Oxytocic drugs

May cause severe persistent hypertension.

Tricyclic antidepressants

May decrease or increase response; use with caution.

Laboratory Test Interactions

Products with potassium guaiacolsulfonate may increase renal Cl for urate and thereby lower serum uric acid levels; may increase urinary 50 hydroxyindoleacetic acid; may falsely elevate VMA test for catecholis.

Adverse Reactions


Angina; arrhythmias; bradycardia; CV collapse with hypotension; fatal subarachnoid hemorrhage; hypertension; MI; syncope; tachycardia.


Anxiety; CNS depression; convulsions; dizziness; excitability; fear; hallucinations; headache; insomnia; nervousness; pallor; restlessness; tremor; weakness.


With ophthalmic and intranasal forms: blurring of vision; rebound congestion; transitory stinging on initial instillation.




Dysuria; urinary retention.


Respiratory difficulty.




Health care providers should completely familiarize themselves with the complete contents of the product information before prescribing phenylephrine injection.


Check BP frequently during continuous infusion; monitor BP in elderly patients with known cardiac disease.


Category C .




Consult a doctor before using the tablets in children younger than 12 y of age; consult a doctor before using the oral liquid in children younger than 2 y of age. Safety and efficacy of 2.5% ophthalmic solution not established. Ophthalmic use of phenylephrine 10% is contraindicated in infants. Use caution in infants with known cardiac anomalies.


Rebound miosis may occur; reinstallation of the drug may produce less mydriasis than previously. Older individuals may also develop transient pigment floaters in the aqueous humor 40 to 45 min after installation.

Special Risk Patients

Administer drug with extreme caution to patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease, prostatic hypertrophy, diabetes mellitus, increased IOP, or severe arteriosclerosis; trouble urinating due to enlarged prostate gland.

Sulfite Sensitivity

Use drug with caution in sulfite-sensitive individuals; some commercial preparations contain sodium bisulfite.

Corneal effects

If corneal epithelium has been denuded or damaged, corneal clouding may occur if phenylephrine 10% is instilled.


Tissue necrosis may develop if extravasation occurs. If it occurs, consider infiltrating phentolamine 5 to 10 mg (diluted in 10 to 15 mL of isotonic sodium chloride solution) into the site of extravasation.


Avoid use in uncorrected hypovolemic states unless used as temporary emergency measure to maintain coronary and cerebral flow and in patients with tachyarrhythmias or ventricular fibrillation.

Narrow-angle glaucoma

Ordinarily any mydriatic is contraindicated in patients with glaucoma. However, when temporary dilation of pupil may free adhesions or when vasoconstriction of intrinsic vessels may lower intraocular tension, these advantages may temporarily outweigh danger from coincident dilation of pupil.

Rebound congestion

May occur with extended use of intranasal or ophthalmic forms.



Coma, hypotension, profuse sweating, sedation, sensation of fullness in head, severe hypertension, shock, short paroxysms of ventricular tachycardia, somnolence, tingling of extremities, ventricular extrasystoles, vomiting.

Patient Information

  • Intranasal
  • Advise patient that intranasal form is for short-term use only and should not be used for more than 3 to 5 days.
  • Inform patient that stinging, burning, or drying of the nose or an increase in nasal discharge may occur.
  • Instruct patient to gradually stop taking intranasal form of this medicine rather than abruptly discontinuing it because rebound congestion can occur with sudden withdrawal. First stop using drug in one nostril and then in both nostrils.
  • Ophthalmic
  • Caution patient that ophthalmic form of drug can cause discoloration of contact lenses and advise patient to wear glasses during therapy.
  • Instruct patient not to use ophthalmic form for greater than 72 h without consulting health care provider.
  • Advise patient to discontinue drug and notify health care provider if severe eye pain, headache, vision changes, floating spots, acute eye redness, pain with light exposure, insomnia, dizziness, weakness, tremor, or irregular heartbeat occurs.
  • Advise patient that drug may cause temporary blurred or unstable vision, and to use caution while driving or performing other tasks requiring mental alertness.

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