phenylephrine hydrochloride (NeoSynephrine, Neofrin)

What is phenylephrine-injection, and how does it work (mechanism of action)?

Phenylephrine is a man-made drug that stimulates receptors (alpha1 receptors) on blood vessels and cause blood vessels to constrict (vasoconstriction). It is a vasoconstrictor medication, structurally similar to epinephrine and ephedrine. Vasoconstriction increases blood pressure. Phenylephrine increases blood pressure and heart rate without affecting heart rhythm.

What brand names are available for phenylephrine-injection?

NeoSynephrine, Neofrin

Is phenylephrine-injection available as a generic drug?


Do I need a prescription for phenylephrine-injection?


What are the side effects of phenylephrine-injection?

Side effects of phenylephrine are headache, reflex bradycardia (slow heart beat), excitability, anxiety, restlessness, high blood pressure, and rarely abnormal heart beats.

What is the dosage for phenylephrine-injection?

Injection: 10 mg/mL supplied as a 1 mL single dose vial

Which drugs or supplements interact with phenylephrine-injection?

Phenylephrine should be used cautiously with MAO inhibitors like selegiline (Eldepryl, Zelapar), phenelzine (Nardil), isocarboxazid (Marplan), because they can also increase blood pressure and can cause a serious hypertensive episode. A similar reaction occurs when phenylephrine is combined with amphetamine and related drugs.

Phenylephrine should be used with caution with antidepressants like amitriptyline (Elavil, Endep), nortriptyline (Pamelor, Aventyl), doxepin (Sinequan, Adapin), and trazodone (Deyrel). Such anti-depressants may increase blood pressure if used together with phenylephrine.


How to Lower Blood Pressure: Exercise and Tips See Slideshow

Is phenylephrine-injection safe to take if I'm pregnant or breastfeeding?

There are no adequate studies done on phenylephrine to determine safe and effective use in pregnant women.

It is not known whether phenylephrine enters breast milk; therefore, it is best to be cautious before using it in nursing mothers.

What else should I know about phenylephrine-injection?

What preparations of phenylephrine-injection are available?

Injection: 10 mg/ml

How should I keep phenylephrine-injection stored?

Store phenylephrine injections between 15 C to 30 C (59 to 86 F).


Phenylephrine hydrochloride injection (NeoSynephrine, Neofrin) is a prescription drug used for the maintenance of blood pressure during treatment of vascular failure in shock, drug-induced high blood pressure, and PSVT during anesthesia. Side effects, drug interactions, storage, dosage, and pregnancy safety information should be reviewed prior to taking any medication.

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FDA Prescribing Information.

Medscape. phenylephrine.