What is Fentanyl: Uses, Warnings & Interactions

Medically reviewed by Kristi C. TorresPharm.D.
Licensed Pharmacist
Updated Oct 8, 2025  •  Published Dec 30, 2020
Fact Checked

Fentanyl is a potent opioid pain reliever used in transdermal extended-release patches to treat severe and persistent pain in people already taking opioids. Fentanyl also comes in other forms like injections, lozenges, and tablets, but these dosage formats contain fentanyl citrate. This article will focus on the use, dosage, and problems of fentanyl skin patches.

Fentanyl overview

BRAND NAMES:

  • No brand-name patch formulations are currently available

  • Formerly branded as Duragesic

Generic Names:

  • Fentanyl

Uses:

  • Pain relief 

Therapeutic Classes:

  • Analgesic, opioid

Forms:

  • Transdermal skin patch

How it’s taken:

  • Absorbed through the skin

What is Fentanyl used for?

Pure fentanyl is only available as extended-release skin patches, which are used to treat severe, persistent pain in people who are already taking opioid pain relievers. A slightly different chemical version of fentanyl called fentanyl citrate is used for other pain conditions and anesthesia.

Key takeaways

  • Fentanyl patches are only appropriate for severe pain in patients who have already been on an opioid regimen for pain. 

  • Patches must remain in their sealed pouch until they are applied to the skin, and they should never be cut.

  • Patches should not be changed more frequently than once every 72 hours and should not be applied to the same skin area as the previous patch.

  • Patches must be kept away from children and disposed of according to the manufacturer's recommendation. Do not throw used patches into a trash can.

  • Fentanyl patches carry the risk of serious and fatal side effects, including respiratory arrest and death. You must only use fentanyl as directed by your healthcare professional.

What form(s) does Fentanyl come in

  • Patch

    • 12 mcg/hour

    • 25 mcg/ hour

    • 37.5 mcg/hour

    • 50 mcg/hour

    • 62.5 mcg/hour

    • 75 mcg/hour

    • 87.5 mcg/hour

    • 100 mcg/hour

For more information about fentanyl dosage formats such as injections, buccal tablets, and lozenges, click here.

What are common Fentanyl doses?

  • For severe and persistent pain in opioid-tolerant adults: One 12–100 mcg/hour transdermal patch worn for 72 hours

Common Fentanyl prescriptions

  • fentaNYL
    1 patch 72 hour of 100mcg/hr box

  • fentaNYL
    1 patch 72 hour of 25mcg/hr box

  • fentaNYL
    1 patch 72 hour of 75mcg/hr box

  • fentaNYL
    5 patch 72 hour box

  • fentaNYL
    5 patch 72 hour of 100mcg/hr box

  • fentaNYL
    5 patch 72 hour of 12mcg/hr box

  • fentaNYL
    5 patch 72 hour of 25mcg/hr box

  • fentaNYL
    5 patch 72 hour of 37.5mcg/hr box

  • fentaNYL
    5 patch 72 hour of 50mcg/hr box

  • fentaNYL
    5 patch 72 hour of 75mcg/hr box

  • fentaNYL
    1 patch 72 hour package

How to take Fentanyl

  • Take your medicine as directed. Your dose may need to be changed several times to find the optimal dose for pain control. 

  • This medicine should come with a Medication Guide and Instructions for Use. Please read both these inserts before starting fentanyl.

  • How to use fentanyl patches

    • Fentanyl patches are only used for severe pain in people already taking an opioid pain medication. 

    • Your doctor will tell you how many patches to use, where to apply them, and how often to do so. The patient instructions can also show you the body areas where the patch can be used. 

    • Do not use more than one patch at a time. 

    • Before applying a fentanyl transdermal patch, remove the old patch and fold it up so the two glued halves stick together. Immediately flush it down the toilet.

    • Only remove a fentanyl patch from its protective pouch when you’re ready to apply the patch.

    • Always make sure that the dose written on the patch is the dose you’ve been prescribed.

    • Tear the wrapper open carefully. NEVER CUT the wrapper or the patch with scissors. 

    • Do not use any patch that has been cut by accident or is damaged. Do not use the patch if the pouch seal is broken.

    • If any medicine leaks out of the patch and gets directly on your skin, wash it off right away with water. 

    • Do not put the new patch in the same place you wore the last one. 

    • Do not put the patch over burns, cuts, or irritated skin. 

    • Immediately wash your hands after applying the patch.

    • Wear the patch for 3 days (72 hours) and remove and dispose of it immediately.

    • If the patch falls off, dispose of it immediately and apply a new patch.

    • You can bathe, shower, or swim, but do not use hot tubs, saunas, tanning beds, tanning lamps, electric blankets, or heating pads over the patch. Do not exercise hard or sunbathe. Anything that increases the temperature of the body or the patch will increase the dose and could cause serious side effects or death.

    • Store the patches at room temperature in the original package in a secure and locked area out of the reach of children and other people.

What to do if you miss a dose of Fentanyl

  • If you forget to wear or change a patch, put one on as soon as possible. Wear the replacement patch for no longer than 3 days (72 hours). 

  • Do not use two patches at once. Always remove the old patch before applying the new one.

Fentanyl contraindications

  • This medicine is not right for everyone. 

  • Fentanyl is not used in people who have:

    • Allergies to fentanyl or similar morphine-like drugs such as codeine.

    • Breathing problems, including slowed breathing and acute or severe bronchial asthma

    • Digestive system obstruction

    • A large intestine that is not working (paralytic ileus)

  • In addition, fentanyl patches are never used in people who:

    • Are not opioid-tolerant 

    • Have mild pain

    • Have temporary, short-term, or intermittent pain

    • Who have pain due to a medical procedure (postoperative pain)

Fentanyl warnings

  • Fentanyl is a hazardous drug that can cause severe problems, including:

    • Slowed breathing (respiratory depression) or stopped breathing (respiratory arrest)

    • Breathing problems while sleeping

    • Serotonin syndrome

    • Adrenal gland dysfunction

    • Drug abuse

    • Dependence

    • Overdose

    • Death

  • Before using this medicine, tell your healthcare provider if you have:

    • Breathing or lung problems such as COPD, asthma, or sleep apnea

    • Liver disease

    • Kidney disease

    • Low blood pressure

    • Slow heartbeats

    • Pancreas or gallbladder problems

    • Stomach or bowel problems

    • A history of seizures, head injury, or brain tumor

    • Mental health issues such as depression

    • A history of alcohol or drug abuse

  • Tell the healthcare provider if you are pregnant or planning to become pregnant before using this medicine.

  • Do not breastfeed while using this medicine.

  • This medicine may make you dizzy, drowsy, or lightheaded. Do not drive or do anything else that could be dangerous until you know how this medicine affects you. 

  • When wearing a fentanyl patch, do not let the patch or the skin under it get too hot. This will increase the dose and could result in serious side effects or death. Avoid direct sunlight and do not use a heating pad, electric blanket, heated waterbed, sauna, sun lamp, or hot tub. Do not exercise hard enough to raise your body temperature. Call your doctor if you have a fever higher than 104 degrees F (40 degrees C).

  • Be careful about letting other people come in contact with your patch. If any medicine gets on another person, wash it off immediately with water and call your doctor.

  • This medicine may cause constipation, especially with long-term use. Ask your doctor if you should use a laxative to prevent and treat constipation.

  • Do not stop using this medicine suddenly. The healthcare provider must slowly decrease the dose before you stop it completely.

  • This medicine can be habit-forming. Do not use more than your prescribed dose. Call the healthcare provider if the medicine is not working.

  • Fentanyl can injure or kill children or other people if they get into it. Keep this medicine locked up in a secure location that children or other people can’t access.

Fentanyl interactions

  • Some medicines can affect how fentanyl works. Tell your healthcare provider if you are using the following: 

    • Medications that treat mental health issues such as depression or anxiety

    • Migraine drugs called triptans

    • Blood pressure medications

    • Drugs that make you pee (diuretics)

    • Anticholinergic drugs

    • Carbamazepine, clarithromycin, erythromycin, fluconazole, itraconazole, ketoconazole, metaxalone, nefazodone, phenytoin, rifampin, or ritonavir

  • Tell your healthcare provider if you use anything else that makes you sleepy. Some examples are: 

    • Allergy medications

    • Other types of opioids

    • Sleeping pills

    • Benzodiazepines

    • Muscle relaxants

    • CBD

    • Alcohol 

  • Do not use this medicine if you are using or have used an MAO inhibitor within the past 14 days.

  • Do not drink alcohol while you are using this medicine.

  • Do not eat or drink grapefruit juice while using this medicine.

Fentanyl side effects

Serious side effects

Talk to a dhealthcare providerif you notice any signs or symptoms of a possible serious side effect, including:

  • Trouble breathing or slow breathing

  • Blue lips, fingernails, or skin

  • Extreme dizziness or weakness, shallow breathing, slow or uneven heartbeat, sweating, cold or clammy skin, seizures

  • Severe constipation, stomach pain, or vomiting

  • Severe confusion, lightheadedness, dizziness, or fainting

  • Anxiety, restlessness, fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, seeing or hearing things that are not there

  • Seizures

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

Less Serious Side Effects

  • Nausea

  • Vomiting

  • Sleepiness

  • Headache

  • Dizziness

  • Trouble sleeping

  • Diarrhea

  • Constipation

Sources:

Medically reviewed by Kristi C. TorresPharm.D.
Licensed Pharmacist

Kristi C. Torres, Pharm.D., is a 2005 graduate of The University of Texas at Austin. Her professional background includes academic teaching roles, district-level management for a nationwide pharmacy chain, and clinic-based pharmacy management. Dr. Torres has a wide range of experience in pharmacy operations and has traveled to many states to open and convert clinic-based pharmacies for one of the largest healthcare systems in the nation.

Currently, she works for Tarrytown Expocare Pharmacy in Austin, Texas, serving the intellectual and developmental disability community. There, she leads the order entry team, overseeing orders from across the country.

Dr. Torres began working in pharmacy at the age of 16 in a small East Texas town. She currently resides in Round Rock, Texas, with her daughter and a Shih-Tzu puppy.

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