March 21, 2017

Phentolamine injection

What is phentolamine injection?

PHENTOLAMINE (Regitine®) treats a number of conditions. It helps to control the sweating and high blood pressure that occur with a disease called pheochromocytoma. Phentolamine can also help diagnose pheochromocytoma. Phentolamine can be used to treat tissue damage that occurs if certain intravenous (IV) medications accidentally leak from veins to tissues. Phentolamine increases blood flow, by expanding the blood vessels. Increase in blood flow to the penis can produce an erection in impotent men, although this is not an approved use. Generic phentolamine injections are available.

What should my health care professional know before I receive phentolamine?

They need to know if you have any of the following conditions:

  • angina

  • previous heart attack

  • coronary disease

  • peptic ulcer

  • an unusual or allergic reaction to phentolamine, other medicines, foods, dyes, or preservatives

  • pregnant or trying to get pregnant

  • breast-feeding

How should I use this medicine?

Phentolamine is for injection into a vein. In most cases, phentolamine is not for self-medication. It is usually given under a prescriber's supervision in a hospital or prescriber's office.

What if I miss a dose?

This does not apply.

What drug(s) may interact with phentolamine?

Do not take phentolamine if you are taking the following medications:

  • other alpha-blockers such as alfuzosin, doxazosin, phenoxybenzamine, prazosin, tamsulosin, terazosin

Phentolamine may also interact with the following medications:

  • alcohol

  • medicines for colds and breathing difficulties

  • medicines for high blood pressure

  • metaraminol

  • methoxamine

  • monoamine oxidase inhibitors (Azilect®, Eldepryl®, Emsam®, Marplan®, Nardil®, Parnate®, Zelapar™)

  • sildenafil

  • tadalafil

  • vardenafil

Tell your prescriber or health care professional about all other medicines you are taking, including nonprescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your prescriber or health care professional before stopping or starting any of your medicines.

What should I watch for while taking phentolamine?

Visit your prescriber or health care professional for regular checks on your progress.

You may feel drowsy or dizzy. Do not drive, use machinery, or do anything that requires mental alertness until you know how phentolamine affects you. To reduce the risk of dizzy or fainting spells, do not sit or stand up quickly. Avoid alcoholic drinks; they can make you more drowsy, and increase flushing and rapid heartbeats. Dizziness can decrease once your body adjusts to this medicine.

Do not take nonprescription medicine for weight-loss without asking your prescriber or health care professional. Also, do not take cough and cold, hay fever or sinus medications without asking your prescriber or health care professional.

If you are going to have surgery, tell your prescriber or health care professional that you are receiving phentolamine.

If you are receiving phentolamine to diagnose pheochromocytoma, do not take any sedatives (drugs to help you sleep) or narcotic pain relievers (such as codeine or morphine) within 24 hours of your test.

What side effects may I notice from receiving phentolamine?

Side effects that you should report to your prescriber or health care professional as soon as possible:

  • dizziness or drowsiness

  • fainting spells

  • fast heartbeat

  • prolonged painful erection of the penis

  • vomiting

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):

  • facial flushing

  • nasal stuffiness

  • nausea

  • sexual difficulties for men

  • unusual tiredness

Where can I keep my medicine?

Keep out of the reach of children.

After mixing the injection solution use immediately, do not store. Throw away any unused portion.


March 21, 2017


U.S. FDA-approved Package Insert