Class Name(s):

• 28:08.08 Opioid Agonists

Pronunciation:

• (fen' ta nil)

IMPORTANT WARNING:

Fentanyl may be habit forming. Tell your doctor if you or anyone in your family drinks or has ever drunk large amounts of alcohol, uses or has ever used street drugs, or has overused prescription medications, or has had an overdose, or if you have or have ever had depression or another mental illness.

Fentanyl may cause serious or life-threatening breathing problems, especially when starting your treatment and any time your dose is increased. If you experience any of the following symptoms after treatment, call your doctor immediately or get emergency medical treatment: slowed breathing, long pauses between breaths, or shortness of breath.

Taking certain other medications, drinking alcohol, or using street drugs with fentanyl may increase the risk that you will develop serious or life-threatening breathing problems, sedation, or coma. Tell your doctor what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the dosages of your medications and will monitor you carefully.

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

Talk to your doctor about the risks of receiving fentanyl injection.

WHY is this medicine prescribed?

Fentanyl is used before and during surgery or other procedures to relieve pain and cause a loss of feeling or awareness. Fentanyl is in a class of medications called narcotic (opiate) analgesics. It works by changing the way the brain and nervous system respond to pain.

HOW should this medicine be used?

Fentanyl injection comes as a solution (liquid) to be injected into a vein or muscle by a doctor or other healthcare provider. Your doctor will determine how much and how frequently to give it to you to maintain anesthesia or sedation.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Are there OTHER USES for this medication?

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

What SPECIAL PRECAUTIONS should I follow?

Before receiving fentanyl,

• tell your doctor or pharmacist if you are allergic to this drug, any part of this drug, or any other drugs, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.
• some medications should not be used with fentanyl. Make sure you have discussed any medications you are currently taking or plan to take with your doctor and pharmacist before you receive fentanyl.
• tell your doctor or pharmacist if you are taking the following medications or have stopped taking them within the past two weeks: isocarboxazid, linezolid, methylene blue, phenelzine, selegiline, or tranylcypromine.
• the following nonprescription or herbal products may interact with fentanyl: St. John's wort and tryptophan. Be sure to let your doctor and pharmacist know that you are taking these medications before you receive fentanyl.
• ell your doctor if you have or have ever had slowed breathing, asthma, chronic pulmonary disease (COPD), or other lung problems, a blockage or narrowing of your stomach or intestines. Your doctor will probably tell you not to receive fentanyl.
• tell your doctor if you have or have ever had a head injury, a brain tumor, or any condition that increases pressure in the brain; seizures; or thyroid, pancreas, gallbladder, heart, liver, or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding.
• you should know that this medication may decrease fertility in men and women when used for a longer period of time. Talk to your doctor about the risks of using fentanyl.
• you should know that fentanyl may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
• ask your doctor about the safe use of alcoholic beverages after you receive fentanyl. Alcohol can make certain side effects from fentanyl worse.
• ou should know that fentanyl may cause dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. To help avoid this problem, get out of bed slowly, resting your feet on the floor for a few minutes before standing up.
• you should know that fentanyl may cause constipation. Talk to your doctor about using other medications to prevent or treat constipation while you receive fentanyl.

What SPECIAL DIETARY instructions should I follow?

Be sure to follow any dietary instructions that your doctor gives to you after your surgery.

What SIDE EFFECTS can this medicine cause?

Fentanyl may cause side effects. Tell your doctor if any of these symptoms or those listed in the SPECIAL PRECAUTIONS section are severe or do not go away:

• nausea, vomiting, diarrhea
• difficulty falling asleep or staying asleep
• sweating
• feeling cold
• loss of appetite
• headache

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately or get emergency medical treatment:

• agitation, hallucinations (seeing things or hearing voices that do not exist), fever, sweating, confusion, fast heartbeat, shivering, severe muscle stiffness or twitching, loss of coordination, or diarrhea
• chest pain, changes in heartbeat
• nausea, vomiting, loss of appetite, weakness, or dizziness
• hives; rash; itching; swelling of the eyes, face, mouth, lips or throat; hoarseness; difficulty breathing or swallowing
• worsening pain, increased sensitivity to pain, or new pain from touch doing ordinary tasks such as combing your hair
• difficulty swallowing, regurgitation (bringing up swallowed food into throat and mouth), pain in the chest area
• seizures
• extreme drowsiness
• unusual snoring or long pauses during breaths during sleep

Fentanyl may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What OTHER INFORMATION should I know?

Keep all appointments with your doctor.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2026. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: September 15, 2025.