What is fentanyl, and how does it work (mechanism of action)?
Fentanyl is a strong, synthetic (man-made) narcotic that is similar to morphine. A 0.1 mg dose of fentanyl is approximately equal to 10 mg of morphine administered by intramuscular injection. Fentanyl stimulates receptors on nerves in the brain to increase the threshold to pain (the amount of stimulation it takes to feel pain) and reduce the perception of pain (the perceived importance of the pain). Fentanyl is available in transdermal (for application to the skin), transmucosal (for application to mucus membranes) and parenteral (injectable) forms. Fentanyl was originally approved by the FDA for injection in 1968.
What brand names are available for fentanyl?
Sublimaze
Is fentanyl available as a generic drug?
Yes
Do I need a prescription for fentanyl?
Yes
What are the side effects of fentanyl?
Fentanyl is a controlled substance and is habit forming. Mental and physical dependence can occur. Abruptly stopping the drug in patients who have been taking the drug for a long time can precipitate a withdrawal reaction. Symptoms of withdrawal include nausea, diarrhea, coughing, tearing, nasal discharge, profuse sweating, twitching muscles, and yawning.
Fentanyl can cause respiratory depression (decreased rate or depth of breathing), muscle rigidity, and reduced heart rate.
Additional side effects are:
- nausea,
- vomiting,
- constipation,
- drowsiness, and
- itching.
Other important side effects include:
- dry mouth,
- abdominal pain,
- loss of appetite,
- confusion,
- headache,
- dizziness,
- nervousness,
- hallucinations,
- anxiety,
- depression, and
- euphoria.

SLIDESHOW
Rheumatoid Arthritis Exercises: Joint-Friendly Workouts See SlideshowWhat is the dosage for fentanyl?
Fentanyl injection can be injected into muscle (intramuscular) or into veins (intravenous). The usual dose for surgical premedication in adults is 0.05 mg to 0.1 mg per dose given by intramuscular injection or by intravenous injection. For anesthesia, the dose is 0.5 to 20 mcg/kg per dose given intravenously. A maintenance intravenous infusion of 1-2 mcg/kg/hour also may be used. There are several recommended regimens for treating pain. Fentanyl also is used for patient-controlled anesthesia (PCA).
Which drugs or supplements interact with fentanyl?
The use of fentanyl with other central nervous system depressants can intensify the depressant effect of fentanyl on breathing, depress the brain, sedate, and lower blood pressure. Other drugs that should be used cautiously with fentanyl include antipsychotics, for example, thorazine, stelazine, and haloperidol (Haldol), anxiolytics, for example, diazepam (Valium), lorazepam (Ativan), and zolpidem (Ambien), certain antihistamines, for example, diphenhydramine (Benadryl) and hydroxyzine (Vistaril), barbiturates, for example, phenobarbital (Donnatal), tricyclic antidepressants, for example, amitriptyline (Elavil, Endep) and doxepin (Sinequan), alcohol, and skeletal muscle relaxants, for example, carisoprodol (Soma), cyclobenzaprine (Flexeril) and baclofen (Lioresal). The use of fentanyl with amiodarone (Cordarone) may result in a slow heart rate. Cimetidine (Tagamet) when used with fentanyl can cause confusion, disorientation, or seizures due to impairment in breathing and brain function.
The monoamine oxidase inhibitor (MAOI) class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Eldepryl), and procarbazine (Matulane) significantly increase the action of fentanyl resulting in more side effects. Fentanyl should not be used in patients taking MAOIs or within 14 days of stopping MAOIs.
Combining fentanyl with drugs that reduce activity of liver enzymes that breakdown fentanyl, for example, ritonavir (Norvir), ketoconazole (Nizoral, Extina, Xolegel, Kuric), itraconazole (Sporanox), troleandomycin, clarithromycin (Biaxin, Biaxin XL), nelfinavir (Viracept), nefazadone, amiodarone, amprenavir (Agenerase), aprepitant, diltiazem (Cardizem, Dilacor, Tiazac), erythromycin, fluconazole (Diflucan), fosamprenavir, and verapamil (Calan, Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS), may result in an increase in fentanyl blood levels, increasing or prolonging side effects of fentanyl.
Latest MedicineNet News
Daily Health News
Is fentanyl safe to take if I'm pregnant or breastfeeding?
Fentanyl can cross the placenta and enter the fetus. Effects on the developing fetus are not known; however, fentanyl can slow breathing in newborn infants whose mothers were exposed to fentanyl. Routine use of fentanyl by pregnant women can lead to withdrawal reactions in the newborn. Thus, caution should be used if fentanyl is administered near the time of delivery.
The effects of fentanyl on the infants of mothers who nurse is unknown. Since most drugs are concentrated in breast milk, it is advisable that women requiring fentanyl bottle-feed their infants.
What else should I know about fentanyl?
What preparations of fentanyl are available?
Injection Solution: 0.05 mg/ml
How should I keep fentanyl stored?
Fentanyl injection should be stored at room temperature 20 C to 25 C (68 F to 77 F) and protect from light.

QUESTION
Medically speaking, the term "myalgia" refers to what type of pain? See AnswerSummary
Fentanyl injection (Sublimaze) is a synthetic narcotic similar to morphine. Fentanyl injection is prescribed to reduce pain before, during, or after surgery. It also is used for treating severe pain that is unrelated to surgery. Side effects, drug interactions, and pregnancy safety information should be reviewed prior to taking this medication.
Multimedia: Slideshows, Images & Quizzes
Related Disease Conditions
-
Pain Management
Pain management and treatment can be simple or complex, according to its cause. There are two basic types of pain, nociceptive pain and neuropathic pain. Some causes of neuropathic pain include: complex regional pain syndrome, interstitial cystitis, and irritable bowel syndrome. There are a variety of methods to treat chronic pain, which are dependant on the type of pain experienced.
-
Chronic Pain
Chronic pain is pain (an unpleasant sense of discomfort) that persists or progresses over a long period of time. In contrast to acute pain that arises suddenly in response to a specific injury and is usually treatable, chronic pain persists over time and is often resistant to medical treatments.
-
Pain Management: Musculoskeletal Pain
Natural menopause is the permanent ending of menstruation that is not brought on by any type of medical treatment. For women undergoing natural menopause, the process is described in three stages: perimenopause, menopause, and postmenopause. However, not all women undergo natural menopause. Some women experience induced menopause as a result of surgery or medical treatments, such as chemotherapy and pelvic radiation therapy.
-
Cancer Pain
Cancer pain results from the tumor pressing on nerves or invading bones or organs. Cancer treatments like chemotherapy, radiation, or surgery can also cause pain. Over-the-counter pain relievers, prescription medications, radiation, biofeedback, and relaxation techniques are just some treatments for cancer pain.
-
Pain Management: Neuropathic Pain
Neuropathic pain is chronic pain resulting from injury to the nervous system. The injury can be to the central nervous system (brain and spinal cord) or the peripheral nervous system (nerves outside the brain and spinal cord).
Treatment & Diagnosis
Medications & Supplements
- What Drugs Are Used for Conscious Sedation?
- What Equipment and Medications Are Required for Endotracheal Intubation?
- Dilaudid vs. Fentanyl (Pain Strength Comparison and Side Effects)
- What Does Sedation Feel Like?
- Benzodiazepines vs. Narcotics (Opioids)
- fentanyl patch (Duragesic)
- What Drugs Are Used for Sedating Children?
- What Are Opioid Equivalents and Conversions?
- Side Effects of Duragesic (fentanyl patch)
- Side Effects of Sublimaze (fentanyl)
- Lazanda (fentanyl) nasal spray
- Subsys (fentanyl)
Prevention & Wellness
- U.S. Saw Big Rise in Meth, Fentanyl Use in 2019
- Deadly Fentanyl Analog Carfentanil Is 100x Stronger Than Fentanyl
- One Region Is Being Hit Hardest by U.S. Opioid Crisis
- All U.S. Adults Should Be Screened for Illicit Drug Use, National Panel Urges
- Lethal Deception: Deaths From Cocaine Laced With Fentanyl on the Rise
- China to Regulate All Fentanyl-Related Drugs
- Drug Users Trying to Stay Ahead of Deadly Fentanyl
- Prince Died From Potent Prescription Painkiller: Autopsy
- Deaths From Drug Poisoning in the U.S Jump by Sixfold
Subscribe to MedicineNet's General Health Newsletter
By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.
Health Solutions From Our Sponsors

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.