Phenylephrine

Phenylephrine constricts blood vessels and increases blood pressure. It is available in prescription and non-prescription formulations and is found in many combination cough-and-cold products.

Phenylephrine Overview

Updated: 

Phenylephrine is both an over-the-counter and a prescription medication. The over-the-counter form is used to treat nasal congestion. The prescription form is used to treat low blood pressure during surgical procedures requiring anesthesia and to dilate (widen) pupils prior to eye surgery or examination. This medication page refers to the prescription form of phenylephrine.

Phenylephrine belongs to a group of drugs called sympathomimetic agents. These work by constricting (narrowing) blood vessels.

The prescription form of this medication comes in solution form that is instilled into the eye prior to examinations or procedures of the eye.

This medication is also available in an injectable form to be given directly into a vein (IV) by a healthcare professional.

Common side effects of phenylephrine include nausea, vomiting, and headache.

Phenylephrine can also cause blurred vision. Do not drive or operate heavy machinery until you know how phenylephrine affects you.

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  • Other
  • Fissure In Ano
  • Glaucoma, Open-angle
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  • Hypotension
  • Pruritus Ani
  • Rhinitis, Vasomotor
  • Shock, Septic
  • Tachycardia, Supraventricular

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Uses of Phenylephrine

Topical:

Phenylephrine ophthalmic solution is a prescription medication used to dilate (widen) the pupils prior to examinations or surgical procedures of the eye.

Injectable:

Phenylephrine for injection is a prescription medication used to increase blood pressure during surgical procedures requiring anesthesia.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Phenylephrine Brand Names

Phenylephrine may be found in some form under the following brand names:

Phenylephrine Drug Class

Phenylephrine is part of the drug class:

Side Effects of Phenylephrine

Serious side effects have been reported with phenylephrine. See the “Phenylephrine Precautions” section.

Topical:

Common side effects of phenylephrine ophthalmic solution include the following:

  • eye pain and stinging
  • blurred vision
  • sensitivity to light
  • increased blood pressure
  • fast or irregular heart beat

Injectable:

Common side effects of phenylephrine for injection include the following:

  • nausea
  • vomiting
  • headache

This is not a complete list of phenylephrine side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Phenylephrine Interactions

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

  • a monoamine oxidase (MAO) inhibitor, such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate)
  • oxytocic drugs such as oxytocin (Pitocin)
  • tricyclic antidepressants such as trimipramine (Surmontil), amitriptyline (Elavil), nortriptyline (Pamelor, Aventyl), protriptyline (Vivactil), and clomipramine (Anafranil)
  • angiotensin-converting enzyme (ACE) blockers such as benazepril (Lotensin, Lotensin HCT), captopril (Capoten, Capozide), enalapril (Vasotec, Vaseretic), fosinopril (Monopril, Monopril HCT), lisinopril (Prinivil, Prinzide, Zestril, Zestoretic), moexipril (Univasc, Uniretic), quinapril (Accupril, Accuretic, Quinaretic), ramipril (Altace), and trandolapril (Mavik, Tarka)
  • angiotensin receptor II blockers such as azilsartan (Edarbi), candesartan (Atacand), irbesartan (Avapro), losartan (Cozaar), olmesartan (Benicar), telmisartan (Micardis, Twynsta), and valsartan (Diovan)
  • atropine (Atropen, DuoDote)
  • steroids, such as hydrocortisone
  • norepinephrine transporter inhibitors, such as atomoxetine (Strattera)
  • ergot alkaloids, such as methylergonovine maleate 
  • α-adrenergic antagonists such as doxazosin (Cardura) and prazosin (Minipress)
  • phosphodiesterase type 5 inhibitors such as avanafil (Stendra), sildenafil (Revatio, Viagra), tadalafil (Cialis), vardenafil (Levitra)
  • certain medications for high blood pressure such as carvedilol (Coreg) and labetalol 
  • calcium channel blockers, such as nifedipine (Adalat, Nifedical, Procardia), amlodipine (Norvasc), verapamil (Calan, Isoptin, Covera, Verelan), and diltiazem (Cardizem)
  • benzodiazepines such as alprazolam (Xanax, Xanax XR), diazepam (Diastat Acudial, Diazepam Intensol, Valium), estazolam, flurazepam, lorazepam (Ativan, Lorazepam Intensol), midazolam, oxazepam, temazepam (Restoril), triazolam (Halcion)
  • centrally acting sympatholytic agents, such as reserpine (Serpalan, Serpasil) and guanfacine

This is not a complete list of phenylephrine drug interactions. Ask your doctor or pharmacist for more information.

Phenylephrine Precautions

Topical:

Serious side effects have been reported with phenylephrine including the following:

  • cardiovascular reactions including irregular heart rates and heart attack
  • significantly elevated blood pressure

Injectable:

Serious side effects have been reported with phenylephrine including the following:

  • worsening of chest pain or heart failure
  • decreased heart rate
  • hypersensitivity (severe allergic reaction). Tell your healthcare provider about any signs or symptoms of hypersensitivity, which include the following:
  • chest pain
  • swelling of the face, eyes, lips, tongue, arms, or legs
  • difficulty breathing or swallowing
  • rash

Phenylephrine can cause blurred vision. Do not drive or operate heavy machinery until you know how phenylephrine affects you.

Do not take phenylephrine if you:

  • are allergic to phenylephrine or to any of its ingredients
  • have high blood pressure
  • have hyperthyroidism
  • are younger than 1 year of age

Phenylephrine Food Interactions

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of phenylephrine, there are no specific foods that you must exclude from your diet when receiving this medication.

Inform MD

Before taking phenylephrine, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • are allergic to phenylephrine or to any of its ingredients
  • have thyroid problems
  • have heart problems
  • have high blood pressure
  • have diabetes
  • have trouble urinating because of an enlarged prostate gland
  • are pregnant or breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Phenylephrine and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X - are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Phenylephrine falls into category C. No studies have been done in animals, and no well-controlled studies have been done in pregnant women. Phenylephrine should be given to a pregnant woman only if clearly needed.

Phenylephrine and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if phenylephrine crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using phenylephrine.

Phenylephrine Usage

Take phenylephrine exactly as prescribed.

Topical:

This medication comes in solution form and is instilled directly into the eye. It is usually administered by a healthcare provider immediately prior to eye examinations or procedures.

Injectable:

This medication comes in solution form and is injected into a vein by a healthcare professional during surgical procedures.

Phenylephrine Dosage

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the condition being treated.

Topical:

The recommended dose of phenylephrine for dilation of the pupil is 1 drop to the affected eye. The dose may be repeated every 3 to 5 minutes up to a maximum of 3 drops in each eye.

Injectable:

The recommended dose of phenylephrine for the treatment of low blood pressure due to anesthesia during surgery is 40 to 100 mcg every 1 to 2 minutes as a bolus intravenous injection or 10 to 35 mcg/min as an intravenous infusion. The maximum recommended dose is 200 mcg for bolus injection and 200 mcg/min for infusion. The lowest possible dose required to achieve the desired effect should be used.

Phenylephrine Overdose

If you take too much phenylephrine, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If phenylephrine is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

Other Requirements

Topical:

  • Store phenylephrine eye drops at room temperature.

Injectable:

  • Store phenylephrine for injection at room temperature.
  • Protect from exposure to light.

Keep this and all medicines out of the reach of children.

Phenylephrine FDA Warning

Topical:

WARNING:

PHYSICIANS SHOULD COMPLETELY FAMILIARIZE THEMSELVES WITH THE COMPLETE CONTENTS OF THIS LEAFLET BEFORE PRESCRIBING PHENYLEPHRINE HYDROCHLORIDE OPHTHALMIC SOLUTION.