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Important Note

The following information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other healthcare professional. It should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. Consult your healthcare professional before using this drug.





This medication is a narcotic pain reliever, generally with anesthesia for surgery or procedures.

How To Use

This medication is given by injection into a muscle (IM) or by slow injection into a vein (IV) by a health care provider. The dose will depend on your condition and response. Use this only as directed. Long-term or excessive use of this medication can cause dependency (or craving for this drug). After a period of time, this medication may not work as well. Consult your doctor or pharmacist.

Side Effects

This medication may cause drowsiness, dizziness, pain at the site of injection, headache, nausea, vomiting, constipation, trouble sleeping or sweating. If these effects persist or worsen, notify your doctor promptly. Report promptly: mental/mood changes, tremors. Unlikely but report promptly: poor coordination, vision problems, difficulty urinating, unusually slow breathing, hallucinations, slow or irregular heartbeat, rash. Very unlikely but report promptly: seizures, fainting. In the unlikely event you have an allergic reaction to this drug, seek medical attention immediately. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing. Laxatives with senna may be helpful for narcotic-related constipation. Consult your doctor and pharmacist before use. If you notice other effects not listed above, contact your doctor or pharmacist.


Before using this drug, tell your doctor your medical history, including: allergies (especially drug allergies), heart problems, kidney problems, liver problems, intestinal problems, lung or breathing problems, enlarged prostate, low blood pressure, low thyroid function, serious head injury, brain disorders, history of drug or alcohol dependency. Alcohol may add to the side effects of this drug, causing drowsiness or dizziness. Ask your doctor or pharmacist about the use of alcohol. Use caution if performing tasks requiring alertness since this medication can cause dizziness and drowsiness. To avoid dizziness and lightheadedness when rising from a seated or lying position, get up slowly. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. Fentanyl passes into breast milk and may have undesirable effects on a nursing infant. Therefore, do not breast-feed without first consulting your doctor. Caution is advised when this drug is used in the elderly because they may be more sensitive to the effects of the drug.

Drug Interactions

Tell your doctor of all nonprescription and prescription medication you may use, especially of: other narcotic pain relievers, tranquilizers, sleeping pills, anti-anxiety drugs, antidepressants, MAO inhibitors (e.g., phenelzine, linezolid, furazolidone, selegiline), droperidol, psychiatric medication (e.g., chlorpromazine), blood pressure drugs (especially water pills), anti-seizure drugs, certain antihistamines (e.g., diphenhydramine), muscle relaxants, cimetidine. This drug may interfere with certain laboratory tests (amylase and lipase). Do not start or stop any medicine without doctor or pharmacist approval.


If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include unusual drowsiness or dizziness, very slow or weak pulse, slow or shallow breathing, muscle rigidity, and loss of consciousness.


Your condition and response to this medication will be closely monitored.

Missed Dose

This medication is only given as needed by a health care professional.


Store at room temperature between 59 and 86 degrees F (15-30 degrees C) away from light and moisture.