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Fentanyl (injection)

Generic Name: fentanyl (injection) (FEN ta nil)
Brand Name:

Medically reviewed: December 12, 2017

What is fentanyl?

Fentanyl is an opioid medication. An opioid is sometimes called a narcotic.

Fentanyl is used as part of anesthesia to help prevent pain after surgery or other medical procedure.

Fentanyl may also be used for purposes not listed in this medication guide.

Important Information

You should not receive this medicine if you are allergic to fentanyl or other narcotic pain medicines.

Before taking this medicine

You should not receive this medicine if you are allergic to fentanyl or other narcotic pain medicines.

To make sure fentanyl is safe for you, tell your doctor if you have ever had:

Some medicines can interact with fentanyl and cause a serious condition called serotonin syndrome. Be sure your doctor knows if you also take stimulant medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. Ask your doctor before making any changes in how or when you take your medications.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant.

Fentanyl can pass into breast milk and may cause side effects in the nursing baby. Tell your doctor if you are breast-feeding.

How is fentanyl given?

Fentanyl is injected into a muscle, or into a vein through an IV. A healthcare provider will give you this injection as part of the anesthesia given for your surgery or medical procedure.

Your breathing, blood pressure, oxygen levels, and other vital signs will be watched closely while you are receiving fentanyl.

You may be given other pain medications to use after your fentanyl treatment is discontinued.

What happens if I miss a dose?

Since fentanyl is given as needed by a healthcare professional for only a short time, you are not likely to be on a dosing schedule.

What happens if I overdose?

Since this medication is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

What should I avoid after receiving fentanyl?

Fentanyl can cause side effects that may impair your thinking or reactions. You should not plan on driving or doing anything that requires you to be awake and alert right after you are treated with this medication. Dizziness or severe drowsiness can cause falls or other accidents.

Avoid drinking alcohol for several hours after you receive fentanyl.

Fentanyl side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Like other narcotic medicines, fentanyl can slow your breathing. Death may occur if breathing becomes too weak.

Your caregivers will watch for any of these side effects you have, which may clear up within minutes after stopping the fentanyl infusion or decreasing the dose:

  • weak or shallow breathing;

  • fast or slow heart rate;

  • stiff muscles; or

  • severe weakness, feeling light-headed or fainting.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Common side effects may include:

  • slowed breathing;

  • slow heart rate;

  • muscle stiffness;

  • dizziness, vision problems;

  • nausea, vomiting;

  • itching, sweating; or

  • high blood pressure (confusion, anxiety, pounding in your neck or ears).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect fentanyl?

Narcotic (opioid) medication can interact with many other drugs and cause dangerous side effects or death. Be sure your doctor knows if you also use:

This list is not complete. Other drugs may interact with fentanyl, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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