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Generic name: fentanyl
Brand names: Actiq, Lazanda, Fentora, Subsys
Dosage form: injection, nasal spray, transdermal patch, sublingual tablet, sublingual spray, transmucosal lozenge (lollipop)
Drug class: Opioids (narcotic analgesics)

Medically reviewed by Melisa Puckey, BPharm. Last updated on May 22, 2024.

What is fentanyl?

Fentanyl is a prescription opioid used to treat moderate to severe pain, but it can be misused, abused, and cause overdose deaths when obtained illegally. Fentanyl is a synthetic opioid medicine that is up to 100 times stronger than other opioids like morphine, heroin, or oxycodone. Fentanyl is from the class of medicines called narcotic analgesics. 

Fentanyl patches are used for long-lasting pain relief, and for fast-acting pain relief, fentanyl nasal sprays, lollipops, injections, sublingual tablets, and sprays are used.

Fentanyl is a prescription medicine that is classified as Schedule 2 under the Controlled Substances Act (CSA).

Fentanyl overdose and abuse

Although fentanyl is a legal prescription drug used for pain control during surgery and for chronic or breakthrough pain, it is also being manufactured illegally, or legal prescriptions are diverted, and fentanyl is misused and abused as it is sold for its euphoric effects.  

Fentanyl overdose symptoms

Fentanyl overdose symptoms may include extreme drowsiness, weak pulse, fainting, and slow breathing (breathing may stop). Seek emergency medical attention immediately or call the Poison Help line at 1-800-222-1222. A fentanyl overdose can be fatal, especially in a child or other person using the medicine without a prescription. 

Naloxone (Narcan) for fentanyl overdose

Naloxone (Narcan nasal spray, Kloxxado nasal spray, Zimhi injection, Naloxone injection) is a safe and easily accessible medication used to reverse an opioid overdose and help restore breathing by blocking or reversing the opioid effects. 

If an overdose is due to fentanyl, then multiple bolus injections of naloxone or even continuous infusions may be needed to reverse the opioid action. Learn how to use naloxone before it is needed.

Fentanyl side effects

Common fentanyl side effects

When used as a prescribed medicine, common fentanyl side effects may include:

Serious fentanyl side effects

Get emergency medical help if you have signs of an allergic reaction to fentanyl: hives, difficulty 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. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue-colored lips, or if you are hard to wake up.

Fentanyl may cause other serious side effects. Call your doctor at once if you have:

Seek medical attention immediately 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.

Serious side effects may be more likely in older adults and those who are malnourished or debilitated.

Long-term use of opioid medication may affect fertility (ability to have children) in men or women. It is not known whether opioid effects on fertility are permanent.

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 the FDA at 1-800-FDA-1088.


Fentanyl can slow or stop your breathing and may be habit-forming. MISUSE OF NARCOTIC MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH, especially in a child or other person using the medicine without a prescription.

Using this medicine during pregnancy may cause life-threatening withdrawal symptoms in the newborn.

Fatal side effects can occur if you use this medicine with alcohol, or with other drugs that cause drowsiness or slow your breathing.

Before taking this medicine

You should not use fentanyl unless you are already being treated with a similar opioid pain medicine and your body is tolerant to it. Talk with your doctor if you are not sure you are opioid-tolerant.

You should only use or take fentanyl if you have your own personal prescription for this medicine. You should not use fentanyl if you are allergic to it or if you have:

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

If you are using fentanyl patches, tell your doctor if you have been sick with a fever. Having a high temperature can increase the amount of drug you absorb through your skin.

Do not change to another form of fentanyl eg injection, skin patch, dissolving film, or "lollipop" device. If you switch from another form of fentanyl, you will not use the same dose.


If you use opioid medicine while you are pregnant, your baby could become dependent on the drug. This can cause life-threatening withdrawal symptoms in the baby after it is born. Babies born dependent on opioids may need medical treatment for several weeks.


Do not breastfeed while you are using fentanyl.

Fentanyl products

Long acting fentanyl:

Immediate acting fentanyl:

What is a fentanyl patch?

Fentanyl patches are applied to the skin to treat moderate to severe chronic pain around the clock. Fentanyl patches are used when other pain treatments, such as non-opioid pain medicines or immediate-release opioid medicines, do not treat your pain well enough or you cannot tolerate them. 

Fentanyl patches are not for treating mild or occasional pain or pain from surgery. The patches are only used to treat constant around-the-clock pain.

One patch is applied to the skin and left on for 72 hours, then you remove the patch and apply a new patch straight away.

Discontinue all other extended-release opioids when beginning therapy.

Due to the risk of respiratory depression, the transdermal patch is for use in opioid-tolerant patients only; opioid-tolerant patients have been taking at least: morphine 60 mg daily, oral oxycodone 30 mg daily, oral hydromorphone 8 mg daily, or an equianalgesic dose of another opioid for one week or longer.


What is a fentanyl sublingual spray?

Fentanyl sublingual spray (brand name: Subsys) is used to treat breakthrough cancer pain that is not controlled by other medicines. Fentanyl sublingual spray is sprayed under the tongue when required for pain. Hold the liquid under the tongue for 30 to 60 seconds. Do not spit, swallow, or rinse your mouth during this time.

Fentanyl sublingual spray should be used together with other non-fentanyl narcotic pain medicines that are used around the clock.

What are fentanyl buccal tablets?

Fentanyl buccal tablets (brand name: Fentora) are used to treat short episodes of "breakthrough" cancer pain that is not controlled by other medicines. The sublingual tablets are used in the mouth but not swallowed whole, instead the tablet is placed inside the mouth between the cheek and gum (buccal) or on the floor of your mouth under your tongue (sublingual) then allowed to dissolve.

Wait 30 minutes after using this medicine. If there is any of the tablet left in your mouth, you may drink a glass of water to help you swallow the leftover medicine.

Do not crush, split, suck, or chew fentanyl tablets, or swallow the tablets whole. You will get less relief for your breakthrough cancer pain.

It is important for you to keep taking your around-the-clock opioid pain medicine while using Fentora.

What are fentanyl ‘lollipops’ or lozenges?

Fentanyl lozenges (brand name: Actiq) are a lozenge containing fentanyl citrate that is attached to a plastic handle (lollipop), they are used to treat breakthrough cancer pain.  They can be used by cancer patients 16 years of age and older who are already receiving and who are tolerant to around-the-clock opioid pain medicine for their background cancer pain.

Place the medicine in your mouth between your cheek and gum, and hold the handle with your fingers. Twirl the handle to move the medicine around in your mouth while sucking on it.

If you switch from using lozenge to using other forms of fentanyl, you will need to use a different dose. Many forms of fentanyl are given at lower doses than the lozenges. If you use the same dose of each medication, you may have life-threatening overdose symptoms.

What is fentanyl nasal spray?

Fentanyl nasal spray (brand name: Lazanda) is a nasal spray that contains fentanyl and is used to treat "breakthrough" pain for cancer patients.

The usual starting dose of fentanyl nasal spray (brand name: Lazanda) is 1 single spray into 1 nostril. Your doctor may change your dose. Follow all directions on your prescription label. Fentanyl can slow or stop your breathing. Never use fentanyl nasal spray in larger amounts, or for longer than prescribed. Tell your doctor if the medicine seems to stop working as well in relieving your pain.

 Patients should also be using around the clock non-fentanyl narcotic pain medicine.

If you switch to fentanyl nasal spray from another form of fentanyl, you will not use the same dose. You must start with the lowest dose (100 micrograms).

What are fentanyl injections used for?

Fentanyl injections are used in a hospital setting as an analgesic or anesthetic premedication for surgery.

General fentanyl dosing information

What happens if I miss a dose?

For fentanyl patches if you are using the skin patches on a schedule, apply the missed patch as soon as you remember. Continue wearing the patch for up to 72 hours and then apply a new one if needed for pain. Do not wear extra patches to make up a missed dose.

For fentanyl lollipops, nasal spray, sublingual tablets or spray since they are used for acute pain, you are not likely to miss a dose of this medicine. Skip any missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. A fentanyl overdose can be fatal, especially in a child or other person using the medicine without a prescription. Overdose symptoms may include extreme drowsiness, weak pulse, fainting, and slow breathing (breathing may stop).

What should I avoid while using fentanyl?

Do not drink alcohol. Dangerous side effects or death could occur.

Fentanyl may impair your thinking or reactions. Avoid driving or operating machinery until you know how this medicine will affect you. Dizziness or severe drowsiness can cause falls or other accidents.

Grapefruit and grapefruit juice may interact with fentanyl and lead to unwanted side effects. Discuss the use of grapefruit products with your doctor.

What other drugs will affect fentanyl?

You may have breathing problems or withdrawal symptoms if you start or stop taking certain other medicines. Tell your doctor if you also use an antibiotic, antifungal medication, heart or blood pressure medication, seizure medication, or medicine to treat HIV or hepatitis C.

Fentanyl 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.

What are the ingredients in fentanyl?

Active ingredient: fentanyl citrate

Inactive ingredients:

Fentanyl Transdermal System (patch) Teva: isopropyl myristate, octyldodecanol, polybutene, and polyisobutene adhesive.

Fentora buccal tablets: mannitol, sodium starch glycolate type A potato, sodium bicarbonate, sodium carbonate, anhydrous citric acid, magnesium stearate.

Subsys sublingual spray: ​​dehydrated alcohol 63.6% (V/V), purified water, propylene glycol, xylitol, and L-menthol

Lazanda nasal spray: mannitol, pectin, phenylethyl alcohol, propylparaben, sucrose, water. Sodium hydroxide and/or hydrochloric acid are added if required for pH adjustment.

Actiq lozenge: sugar, citric acid, dibasic sodium phosphate, artificial berry flavor, magnesium stearate, modified food starch and confectioner’s sugar.

Popular FAQ

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When illegally used fentanyl is abused or taken in an overdose, this opioid can quickly be fatal because it is so potent and people are not used to its effects. Fentanyl is often laced into street drugs and consumed unknowingly by users, leading to death. Also, when it's used in combination with other central nervous system depressants like opioids, alcohol or benzodiazepines, the risk of overdose and death multiplies. Continue reading

Traces of fentanyl can stay in your system for a lot longer than it takes for the effects of fentanyl to wear off. Drug testing can detect fentanyl or its metabolites (breakdown products) in urine for 24 to 72 hours, in blood for 5 to 48 hours, and in hair for up to 3 months, but it cannot be consistently detected in saliva. Continue reading

Fentanyl test strips can be found at your local health department, at a community needle-exchange program, from reliable online sources, or even vending machines in some states. Once the strip is dipped into a sample of the drug (usually dissolved in a small amount of water), the results indicate if fentanyl is present. Follow the instructions for use on your specific test strips. Continue reading

A fentanyl overdose may result in signs and symptoms such as:

  • stupor (dazed or nearly unconscious)
  • coma (cannot be awakened, unable to speak)
  • pupil constriction
  • slowed or absent breathing (respiratory depression or failure)
  • cyanosis (bluish or purplish tint to the skin, lips or fingernails due to low oxygen levels)
  • vomiting
  • heartbeat slows or stops
  • death
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Both illicit fentanyl and carfentanil are extremely dangerous opioids that may lead to a quick overdose and death when abused, but carfentanil is more potent than fentanyl. Multiple doses of the anti-overdose drug naloxone (Narcan) may not be effective to reverse an overdose. Continue reading

Fentanyl is an extremely potent, synthetic (man-made) opioid. It is about 50 times more potent than heroin and 100 times more potent than morphine. In contrast, heroin is 2 to 3 times more powerful than morphine. Fentanyl is a legally prescribed drug for pain in the US and is classified as Schedule II controlled substance when used for legitimate purposes. Heroin is illegal in the U.S. and is classified as a Schedule I controlled substance. Continue reading

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