Fentanyl

Pronunciation: FEN-tuh-nil.

Generic name
fentanyl
Brand names
Duragesic, Durogesic, Sublimaze, Actiq, Fentora, Abstral
Drug class
Opioid analgesic (synthetic, Schedule II controlled substance in the United States)
Form
Transdermal patch, injection, buccal tablet, sublingual tablet or spray, lozenge, or nasal spray -- exact formulation prescribed depends on the clinical situation and is never interchangeable microgram-for-microgram between formulations
Route
Transdermal (skin patch), intravenous/intramuscular injection, or transmucosal (buccal, sublingual, or intranasal) depending on formulation
Legal status
Prescription-only, controlled substance

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Durogesic; Denpax (6) · Full directory

What fentanyl is and how it works

Fentanyl is a potent, prescription-only synthetic opioid analgesic used to manage severe pain that cannot be adequately controlled by other treatments. It is available in several distinct formulations -- long-acting transdermal patches for continuous chronic pain, immediate-release transmucosal products (lozenge, buccal or sublingual tablet, sublingual spray, or nasal spray) for breakthrough cancer pain only, and injectable forms used only in monitored medical/anaesthesia settings. (1) (2)

Fentanyl is a very potent opioid -- reported to be roughly 50 to 100 times more potent than morphine -- and is intended only for patients who are already opioid-tolerant and for whom other pain treatments are inadequate. It is never appropriate for opioid-naive patients, mild pain, short-term or occasional pain, or postoperative pain. Because even a small accidental exposure can be fatal, especially to a child, safe storage, use, and disposal exactly as instructed are essential.

Mechanism of action: how fentanyl works

Fentanyl is a synthetic opioid agonist acting primarily at the mu-opioid receptor in the central nervous system, inhibiting ascending pain pathways and altering the perception of and response to pain; it also produces generalised central nervous system depression, which underlies its respiratory-depressant and sedative effects. Fentanyl is reported to be approximately 50-100 times more potent than morphine. (1)

What fentanyl is used for

Severe chronic pain requiring continuous opioid treatment (transdermal patch)

Long-acting fentanyl patches are used for the management of pain in opioid-tolerant patients that is severe enough to require daily, around-the-clock, long-term opioid treatment, and for which alternative treatments are inadequate. Patches are not for as-needed (PRN) use. (1)

Breakthrough pain in cancer (immediate-release transmucosal forms only)

Immediate-release transmucosal fentanyl products (lozenge, buccal or sublingual tablet, sublingual spray, or nasal spray) are used only for breakthrough pain episodes in cancer patients who are already opioid-tolerant and already receiving around-the-clock opioid therapy for their underlying persistent cancer pain. They are not appropriate for other types of pain. (2)

Anaesthesia and analgesia adjunct (injectable form)

Injectable fentanyl is used by anaesthesia and other specially trained clinicians, in a monitored setting, as part of anaesthesia or for pain management, including for procedures and in intensive care. (5)

Before taking fentanyl

Do not take / not appropriate for

  • Do not use a fentanyl transdermal patch unless you are already opioid-tolerant. Patches are contraindicated in opioid-naive patients, for acute or intermittent pain, postoperative pain, mild pain, or as an as-needed (PRN) analgesic. (all countries) (1)
  • Do not use any immediate-release transmucosal fentanyl product (lozenge, buccal/sublingual tablet, sublingual spray, or nasal spray) unless you are an opioid-tolerant cancer patient already on around-the-clock opioid therapy for breakthrough cancer pain -- these are not appropriate for any other type of pain or for opioid-naive patients. (all countries) (2)
  • Do not use fentanyl if you have significant respiratory depression, acute or severe asthma in an unmonitored setting or without resuscitation equipment available, or a known or suspected bowel obstruction (including paralytic ileus). (all countries) (1)
  • Do not use fentanyl if you have had a hypersensitivity reaction to fentanyl or any component of the specific product. (all countries) (1)

Tell your clinician about

  • Whether you are opioid-tolerant, and exactly which other opioids and doses you have been taking and for how long.
  • Any personal or family history of substance use disorder, addiction, or misuse of alcohol or drugs.
  • Any breathing problems, lung disease (such as COPD or severe asthma), or sleep apnoea.
  • All other medicines you take, especially benzodiazepines, sedatives, other CNS depressants, alcohol, or any medicine that affects the CYP3A4 liver enzyme (many common antifungals, some antibiotics, and HIV medicines, among others).
  • Any history of head injury, increased pressure in the brain, or impaired consciousness.
  • Pregnancy, plans for pregnancy, or breastfeeding.
  • Any liver or kidney problems.
  • For patches: any plans for direct heat exposure to the patch area (heating pads, electric blankets, saunas, hot tubs, sunbathing, heated water beds) or fever, since these can dangerously increase how much fentanyl is absorbed.
(1) (2)

How to take fentanyl

  • Use exactly the formulation, strength, and schedule your prescriber has set -- fentanyl products are not interchangeable with each other, even at what might seem like an equivalent dose.
  • For patches: apply to intact, non-irritated, non-irradiated skin on a flat area such as the chest, back, flank, or upper arm; each patch is worn continuously for 72 hours unless your prescriber directs otherwise.
  • Never cut, damage, or otherwise alter a fentanyl patch -- doing so can release its contents all at once and cause a fatal overdose.
  • Keep the patch application site and surrounding skin away from direct external heat sources (heating pads, electric blankets, heat or tanning lamps, sunbathing, hot baths, saunas, hot tubs, heated water beds), and tell your prescriber promptly if you develop a fever, since heat can dangerously increase how much fentanyl your body absorbs.
  • Dispose of a used patch immediately upon removal by folding the sticky sides together and flushing it down the toilet; unused patches should have the liner removed, be folded sticky-side to sticky-side, and also be flushed down the toilet -- this is the labelled disposal method precisely because accidental exposure to even one patch can be fatal, especially to a child or pet.
  • For immediate-release transmucosal products: use only for breakthrough cancer pain as instructed, and never share your medicine, since a dose that is safe for you can be fatal to someone who is not opioid-tolerant.
  • Any change to your dose, or any decision to reduce or stop treatment, should be made together with your prescriber -- do not adjust your own dose or stop fentanyl on your own, since rapid discontinuation in a physically dependent patient has been associated with serious withdrawal symptoms, uncontrolled pain, and, rarely, suicide; your prescriber will set an individualised, gradual tapering plan if treatment is being reduced or ended.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7)

Missed dose

Contact your prescriber for guidance specific to your formulation and schedule if you miss a dose -- do not apply an extra patch or take an extra dose of a transmucosal product to make up for a missed one.

Overdose

A fentanyl overdose is a medical emergency. Signs include slow, shallow, or stopped breathing, extreme drowsiness or inability to wake, pinpoint pupils, cold or clammy skin, and loss of consciousness. Call emergency services immediately. If naloxone is available, it can be given while waiting for emergency help, but emergency medical attention is still required because fentanyl's effects can outlast a single dose of naloxone. Remove a patch immediately if one is being worn. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Nausea and vomiting.

What to notice: Nausea and vomiting.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Drowsiness (somnolence) and dizziness.

What to notice: Drowsiness (somnolence) and dizziness.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Constipation.

What to notice: Constipation.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Sweating (hyperhidrosis), feeling cold, fatigue, loss of appetite, headache, insomnia, and diarrhoea.

What to notice: Sweating (hyperhidrosis), feeling cold, fatigue, loss of appetite, headache, insomnia, and diarrhoea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Mild skin irritation at the patch application site.

What to notice: Mild skin irritation at the patch application site.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of life-threatening respiratory depression — boxed_warning

Symptoms: Slow, shallow, or stopped breathing, extreme drowsiness, confusion, or inability to wake up.

Action: Seek emergency medical help immediately. This risk is highest when starting treatment or after a dose increase. (1)

Accidental exposure to fentanyl (yourself, a child, or another person) — boxed_warning

Symptoms: Unusual drowsiness, slowed or difficult breathing, or unresponsiveness in anyone who may have accidentally touched or ingested a patch or other fentanyl product.

Action: Seek emergency medical help immediately -- accidental exposure to even one dose can be fatal, especially in children. Always follow the exact storage and disposal instructions you have been given. (1)

Addiction, abuse, or misuse — boxed_warning

Symptoms: Using more medicine than prescribed, using it more often, or strong urges to use it.

Action: Discuss any concerns about dependence, cravings, or misuse openly and promptly with your prescriber -- this is a recognised risk of fentanyl treatment, not a personal failing, and your prescriber can help. (1)

Neonatal opioid withdrawal syndrome (with prolonged use in pregnancy) — boxed_warning

Symptoms: In a newborn exposed to fentanyl in the womb: irritability, poor feeding, tremors, or breathing problems shortly after birth.

Action: This requires specialist neonatal management; discuss the risk with your prescriber and obstetric team well before delivery if you are being treated with fentanyl during pregnancy. (1)

Serotonin syndrome (with serotonergic medicines) — emergency

Symptoms: Agitation, hallucinations, a fast heartbeat, high body temperature, muscle rigidity or twitching, loss of coordination, nausea, vomiting, or diarrhoea.

Action: Seek emergency medical help immediately; a clinician will urgently assess whether fentanyl needs to be stopped if serotonin syndrome is suspected. (1)

Signs of a serious allergic reaction — emergency

Symptoms: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread rash or hives.

Action: Seek emergency medical help immediately. (1)

Withdrawal symptoms from stopping or reducing treatment too quickly — high caution

Symptoms: Restlessness, watery eyes, runny nose, yawning, sweating, chills, muscle aches, irritability, anxiety, or abdominal cramps.

Action: Work with your prescriber on a gradual, individualised tapering plan rather than adjusting or stopping treatment on your own -- rapid discontinuation in a physically dependent patient has been linked to serious withdrawal, uncontrolled pain, and rare cases of suicide. (1)

Interactions

  • Medicines that inhibit the CYP3A4 liver enzyme can raise fentanyl blood levels and cause potentially fatal respiratory depression; stopping a medicine that induces CYP3A4 can have a similar effect. Tell your prescriber about every medicine you take. (1)
  • Benzodiazepines, other sedatives, and alcohol combined with fentanyl can cause profound sedation, life-threatening respiratory depression, coma, and death. This combination is reserved for situations where there is no adequate alternative, at the lowest effective doses. (1)
  • Serotonergic medicines (for example, some antidepressants) combined with fentanyl can cause serotonin syndrome, a potentially life-threatening condition. (1)
  • Mixed agonist/antagonist or partial-agonist opioids (such as certain other pain medicines) can reduce fentanyl's pain-relieving effect or trigger withdrawal symptoms and are generally avoided in combination. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Prolonged fentanyl use during pregnancy can cause neonatal opioid withdrawal syndrome, which may be life-threatening without recognition and specialist neonatal treatment. Available human data are not sufficient to establish the risk of major birth defects or miscarriage; animal studies showed effects at clinically relevant doses. Discuss the risks and benefits of any opioid treatment during pregnancy with your prescriber and obstetric team. (1) (2) (3) (4) (5) (6) (7)

Breastfeeding

Fentanyl passes into breast milk. Breastfeeding is not recommended during fentanyl treatment because of the risk of excess sedation and respiratory depression in the breastfed infant; any infant exposed through breast milk needs to be monitored for these effects. (1) (2) (3) (4) (5) (6) (7)

Children

Some transdermal patch formulations are approved for long-term management of severe chronic pain in opioid-tolerant children from around 2 years of age in some markets; immediate-release transmucosal products for breakthrough cancer pain are restricted to specific minimum ages (commonly 16 or 18 years, depending on the product) -- always follow the age restriction and opioid-tolerance requirement for the specific product prescribed. (1) (2) (3) (4) (5) (6) (7)

Elderly

Very elderly, frail, or debilitated patients are more sensitive to opioid effects, including life-threatening respiratory depression; starting opioid treatment with a fentanyl patch is not recommended in this population, and closer monitoring is needed throughout treatment. (1) (2) (3) (4) (5) (6) (7)

Hepatic_impairment

Mild-to-moderate hepatic impairment: your prescriber may start you on a lower dose and titrate more slowly, with closer monitoring for sedation and breathing problems. Severe hepatic impairment: use is generally not recommended. (1) (2) (3) (4) (5) (6) (7)

Renal_impairment

Mild-to-moderate renal impairment: your prescriber may start you on a lower dose and titrate more slowly, with closer monitoring. Severe renal impairment: use is generally not recommended. (1) (2) (3) (4) (5) (6) (7)

Monitoring

Before starting

  • Confirmation of opioid tolerance and prior analgesic history.
  • Assessment of risk factors for addiction, abuse, and misuse.
  • Review of breathing/lung conditions and all other medicines, especially CYP3A4-interacting drugs, benzodiazepines, and other CNS depressants.
  • Discussion of naloxone availability with the patient and caregiver, based on individual overdose risk factors.

During treatment

  • Close monitoring for respiratory depression and sedation, especially during the first 24-72 hours of a new patch or after any dose increase.
  • Ongoing review for signs of misuse, abuse, or dependence.
  • Monitoring for fever or heat exposure that could increase fentanyl absorption from a patch.
  • Regular reassessment of whether continued opioid treatment remains necessary, and of the tapering plan if treatment is being reduced.
(1)

Storage

Store at controlled room temperature, out of sight and reach of children, in a secure location given its high risk of diversion, misuse, and fatal accidental exposure. Dispose of used and unused patches by folding the adhesive sides together and flushing down the toilet, exactly as instructed by your prescriber or pharmacist, as soon as they are no longer needed.

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information (Duragesic, Revised 03/2021) and the TIRF REMS program materials; verify against the current full label for the specific product and formulation before prescribing.

United States

Indication: Severe chronic pain in opioid-tolerant patients (transdermal patch)

Dose summary: Opioid-tolerant defined as: taking, for one week or longer, at least 60 mg oral morphine/day, 25 mcg transdermal fentanyl/hour, 30 mg oral oxycodone/day, 8 mg oral hydromorphone/day, 25 mg oral oxymorphone/day, 60 mg oral hydrocodone/day, or an equianalgesic dose of another opioid. Each patch is worn for 72 hours. Initiate at the lowest effective dose; individualise based on pain severity, prior opioid experience, and risk factors. Mild-to-moderate hepatic/renal impairment: initiate at one-half the usual starting dose and titrate slowly. Not indicated as a PRN analgesic. Contraindicated in opioid-non-tolerant patients, acute/intermittent/postoperative/mild pain.

Renal context: Severe hepatic and renal impairment: use is not recommended. Mild-to-moderate impairment: start at one-half the usual dose and titrate slowly with close monitoring. (1)

Mechanism of action

Hepatic guidance

Use with caution in hepatic impairment; mild-to-moderate impairment warrants a reduced starting dose and slower titration, and severe impairment is generally not recommended for outpatient use.

Overdose note

Fentanyl overdose presents with respiratory depression, sedation, miosis, and hypotension progressing to circulatory and respiratory failure. Management requires airway support, ventilatory assistance, and titrated naloxone, with extended monitoring because fentanyl's respiratory-depressant effects may outlast a single naloxone dose, particularly with patch formulations where a depot of drug remains in the skin. (1)

Frequently asked questions

Is fentanyl available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, fentanyl in various formulations (transdermal patch, injection, and historically immediate-release transmucosal products) is approved and available in all of these regions, under prescription-only, controlled-substance status. (1) (3) (4) (5) (6) (7)

Can I use a fentanyl patch for short-term or occasional pain, such as after surgery?

No. Fentanyl patches are contraindicated for acute, intermittent, postoperative, or mild pain, and for use as an as-needed analgesic. They are intended only for continuous, around-the-clock treatment of severe chronic pain in patients who are already opioid-tolerant. (1)

How should I dispose of a used fentanyl patch?

Fold the sticky sides of the patch together immediately after removal, then flush it down the toilet. Unused patches should have the liner removed, be folded sticky-side to sticky-side, and also be flushed down the toilet. This method is specified in the label because even a used patch can contain enough fentanyl to be fatal to a child, pet, or anyone who is not opioid-tolerant. (1)

What should I do if a fentanyl patch falls off?

Dispose of the fallen-off patch safely (fold sticky sides together and flush) and apply a new patch to a different skin site as your prescriber has instructed. Tell your prescriber if this happens frequently. (1)

Why can't I use heating pads or take hot baths while wearing a fentanyl patch?

Direct heat over or near the patch increases how much fentanyl your skin absorbs and has caused fatal overdoses. Avoid heating pads, electric blankets, heat or tanning lamps, sunbathing, hot baths, saunas, hot tubs, and heated water beds while wearing a patch, and tell your prescriber if you develop a fever. (1)

What is the mechanism of action of fentanyl?

Fentanyl is a synthetic opioid agonist acting primarily at the mu-opioid receptor in the central nervous system, inhibiting ascending pain pathways and altering the perception of and response to pain; it also produces generalised central nervous system depression, which underlies its respiratory-depressant and sedative effects. Fentanyl is reported to be approximately 50-100 times more potent than morphine. (1)

What is the generic name of Fentanyl?

The generic name is fentanyl. It is sold under brand names including Duragesic, Durogesic, Sublimaze, Actiq, Fentora, Abstral. (1) (2)

What class of drug is fentanyl?

Fentanyl is classed as: Opioid analgesic (synthetic, Schedule II controlled substance in the United States). (1) (2)

References

  1. DURAGESIC (fentanyl transdermal system), CII -- Full Prescribing Information, Revised 03/2021U.S. Food and Drug Administration -- approved full prescribing information (PDF), Janssen Pharmaceuticals · United States · accessed 2026-07-29 · source 1
  2. TIRF REMS Access program -- Abstral/Actiq/Fentora/Lazanda/Onsolis/Subsys prescribing restrictionU.S. Food and Drug Administration -- TIRF (Transmucosal Immediate-Release Fentanyl) REMS program materials · United States · accessed 2026-07-29 · source 2
  3. Durogesic DTrans Transdermal Patch -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Janssen-Cilag · United Kingdom · accessed 2026-07-29 · source 3
  4. Fentanyl-ratiopharm matrix patch Article 29 referral; Effentora European Public Assessment ReportEuropean Medicines Agency (EMA) -- Article 29/31 referral outcomes for fentanyl transdermal and immediate-release products; Effentora EPAR · European Union · accessed 2026-07-29 · source 4
  5. DURAGESIC (fentanyl transdermal system) Product MonographHealth Canada product monograph · Canada · accessed 2026-07-29 · source 5
  6. DUROGESIC / DENPAX fentanyl transdermal patch -- ARTG registrationTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 6
  7. Fentanyl Injection / Durogesic New Zealand Data SheetsMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-29 · source 7

Brand names by country

Single-ingredient fentanyl names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • FENTANYL TRANSDERMAL12.5 ug/h, 62.5 ug/h, 100 ug/h, 37.5 ug/h, 75 ug/h, 50 ug/h, 25 ug/h · specgx llc
  • Fentanyl system25 ug, 12.5 ug, 75 ug, 100 ug, 50 ug · alvogen

United Kingdom

  • Durogesic DTrans (3)MHRA licensed emc smpc confirmed · 12, 25, 50, 75, 100 mcg/hour patch · Janssen-Cilag Ltd

Canada

  • ABSTRAL
  • DURAGESIC
  • CO FENTANYL
  • FENTORA
  • FENTANYL CITRATE INJECTION SDZ
  • RAN-FENTANYL MATRIX
  • PMS-FENTANYL MTX
  • MYLAN-FENTANYL MATRIX
  • APO-FENTANYL MATRIX

Australia

  • Durogesic; Denpax (6)TGA ARTG registered confirmed · 12, 25, 50, 75, 100 mcg/hour patch · Janssen-Cilag Pty Ltd / Alphapharm

New Zealand

  • Durogesic; Fentanyl Injection (Sandoz/Medsurge/DBL) (7)Medsafe approved confirmed · 12, 25, 50, 75, 100 mcg/hour patch, injection, various strengths · Janssen-Cilag (NZ) Ltd and multiple injection suppliers
View brands in additional countries.

European Union

Effentora (buccal tablet, centrally authorised); Durogesic/fentanyl patches (nationally authorised) (4)

This page provides general medicine information, not a diagnosis, prescription, or substitute for a pain-medicine specialist, prescriber, pharmacist, or the current local product information for the exact fentanyl formulation prescribed.

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