Fentanyl Side Effects
Medically reviewed by Drugs.com. Last updated on Aug 7, 2023.
Applies to fentanyl: lozenge/troche, spray, tablet. Other dosage forms:
Sublingual route (Spray)
Warning: Life-Threatening Respiratory Depression, Accidental Ingestion; Cytochrome P450 3A4 Interaction; Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants; Risk of Medication Errors; Addiction, Abuse, and Misuse; REMS; and Neonatal Opioid Withdrawal SyndromeSerious, life-threatening, and/or fatal respiratory depression has occurred. Monitor closely, especially upon initiation or following a dose increase. Due to the risk of fatal respiratory depression, fentanyl sublingual spray is contraindicated in opioid non-tolerant patients and in management of acute or postoperative pain, including headache/migraines.Accidental ingestion of fentanyl sublingual spray, especially by children, can result in a fatal overdose of fentanyl. Keep out of reach of children. Ensure proper storage and disposal.Concomitant use with CYP3A4 inhibitors (or discontinuation of CYP3A4 inducers) can result in a fatal overdose of fentanyl.Concomitant use of opioids with benzodiazepines or other CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for use in patients for whom alternative treatment options are inadequate; limit dosages and durations to the minimum required and follow patients for signs and symptoms of respiratory depression and sedation.When prescribing, do not convert patients on a mcg per mcg basis from any other oral transmucosal fentanyl product to fentanyl sublingual spray.When dispensing, do not substitute with any other fentanyl products.Fentanyl sublingual spray exposes users to risks of addiction, abuse, and misuse, which can lead to overdose and death. Assess patient’s risk before prescribing and monitor regularly for these behaviors and conditions.Fentanyl sublingual spray is available only through a restricted program called the TIRF REMS Access program. Outpatients, healthcare professionals who prescribe to outpatients, pharmacies, and distributors are required to enroll in the program.Prolonged use of fentanyl sublingual spray during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated. If prolonged opioid use is required in a pregnant woman, advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available..
Buccal mucosa route (Film; Lozenge/Troche; Tablet)
Due to the risk of fatal respiratory depression, transmucosal fentanyl citrate is contraindicated in opioid non-tolerant patients and in management of acute or postoperative pain, including headache/migraines. Monitor for respiratory depression during treatment. Accidental ingestion of fentanyl can result in a fatal overdose, especially in children; keep out of reach of children. Use with CYP3A4 inhibitors or inducers may change fentanyl plasma levels resulting in a fatal overdose of fentanyl and monitoring is recommended. Concomitant use of opioids with benzodiazepines or other CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients with inadequate alternative treatment options, limit dosage and duration to the minimum required, and monitor for respiratory depression and sedation. When prescribing, do not convert patients on a mcg per mcg basis from any other fentanyl products. When dispensing, do not substitute with any other fentanyl products. Fentanyl is a Schedule II controlled substance with abuse liability similar to other opioid analgesics. Assess risk prior to initiation and monitor for signs of misuse, abuse, and addiction during treatment. Only available through a restricted program called the Transmucosal Immediate Release Fentanyl Risk Evaluation and Mitigation Strategy (TIRF REMS) Access program. Outpatients, healthcare professionals who prescribe to outpatients, pharmacies, and distributors are required to enroll in the program. Prolonged use during pregnancy may result in neonatal opioid withdrawal syndrome. If prolonged use is required in a pregnant woman, advise patient of potential fetal risk and ensure appropriate treatment will be available.
Sublingual route (Tablet)
Due to the risk of fatal respiratory depression, sublingual fentanyl citrate is contraindicated in opioid non-tolerant patients and in management of acute or postoperative pain, including headache/migraines. Monitor for respiratory depression during treatment. Accidental ingestion of fentanyl can result in a fatal overdose, especially in children; keep out of reach of children. Use with CYP3A4 inhibitors or inducers may change fentanyl plasma levels resulting in fatal overdose and monitoring is recommended. Concomitant use of opioids with benzodiazepines or other CNS depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing for patients with inadequate alternative treatment options, limit dosage and duration to the minimum required, and monitor for respiratory depression and sedation. When prescribing, do not convert patients on a mcg per mcg basis from any other fentanyl products. When dispensing, do not substitute with any other fentanyl products. Fentanyl is a Schedule II controlled substance with abuse liability similar to other opioid analgesics. Assess risk prior to initiation and monitor for signs of misuse, abuse, and addiction during treatment. Only available through a restricted program called the Transmucosal Immediate Release Fentanyl Risk Evaluation and Mitigation Strategy (TIRF REMS) Access program. Outpatients, healthcare professionals who prescribe to outpatients, pharmacies, and distributors are required to enroll in the program. Prolonged use during pregnancy may result in neonatal opioid withdrawal syndrome. If prolonged use is required in a pregnant woman, advise patient of potential fetal risk and ensure appropriate treatment will be available.
Serious side effects of Fentanyl
Along with its needed effects, fentanyl may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur while taking fentanyl:
- Black, tarry stools
- blurred vision
- chest pain
- decreased urine
- difficult or labored breathing
- dry mouth
- fever or chills
- increased thirst
- irregular heartbeat
- loss of appetite
- lower back or side pain
- mood changes
- muscle pain or cramps
- nausea or vomiting
- numbness or tingling in the hands, feet, or lips
- painful or difficult urination
- pale skin
- pounding in the ears
- rapid breathing
- sore throat
- sunken eyes
- swelling of the hands, ankles, feet, or lower legs
- tightness in the chest
- troubled breathing with exertion
- ulcers, sores, or white spots in the mouth
- unusual bleeding or bruising
- unusual tiredness or weakness
- wrinkled skin
- Abdominal or stomach pain
- change in walking and balance
- clumsiness or unsteadiness
- decreased awareness or responsiveness
- decreased frequency of urination
- muscle twitching or jerking
- pounding in the ears
- rhythmic movement of the muscles
- seeing, hearing, or feeling things that are not there
- severe constipation
- severe sleepiness
- shakiness in the legs, arms, hands, or feet
- slow or fast heartbeat
- thinking abnormalities
- trembling or shaking of the hands or feet
Get emergency help immediately if any of the following symptoms of overdose occur while taking fentanyl:
Symptoms of overdose
- Extremely shallow or slow breathing
Other side effects of Fentanyl
Some side effects of fentanyl may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.
Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Back pain
- difficulty having a bowel movement (stool)
- difficulty with moving
- feeling sad or empty
- lack or loss of strength
- loss of interest or pleasure
- muscle stiffness
- pain in the joints
- sleepiness or unusual drowsiness
- trouble concentrating
- trouble sleeping
- weight loss
- Changes in vision
- excessive muscle tone
- feeling of constant movement of self or surroundings
- feeling of warmth or heat
- flushing or redness of the skin, especially on the face and neck
- irritation, pain, or sores at the site of application
- itching skin
- muscle tension or tightness
- sensation of spinning
Incidence not known
- Tooth pain
- trouble with gums
- trouble with teeth
For Healthcare Professionals
Applies to fentanyl: buccal film, buccal tablet, compounding powder, injectable solution, intravenous solution, nasal spray, oral lozenge, oral transmucosal lozenge, sublingual spray, sublingual tablet, transdermal device, transdermal film extended release.
The most commonly reported adverse reactions included headache, nausea, vomiting, ,dizziness, and constipation.[Ref]
Very common (10% or more): Somnolence, dizziness
Common (1% to 10%): Sedation, pyrexia, fatigue, lethargy, tremor, headache, chills, irritability, malaise, confusion, abnormal thinking, anxiety, dysphoria
Uncommon (0.1% to 1%): Hyperesthesia
Very rare (less than 0.01%): Severe hemiplegic migraine
Frequency not reported: Slurred speech, paresthesia, hypesthesia, tremor
Postmarketing reports: Loss of consciousness, vertigo, coma, shock, convulsion[Ref]
Cases of seizures have occasionally been reported, but some investigators have suggested that the seizure-like events reported may have been episodes of fentanyl induced-rigidity.[Ref]
Common (1% to 10%): Tachycardia
Uncommon (0.1% to 1%): Sinus tachycardia, chest pain, hypertension, hypotension, palpitations
Rare (less than 0.1%): Arrhythmias, cardiac arrest
Frequency not reported: Syncope, vasodilation, bradycardia, bigeminy, myocardial infarct
Postmarketing reports: Circulatory depression[Ref]
One report has suggested that epidural fentanyl may mask the pain of myocardial ischemia in patients treated with fentanyl for other reasons. Another report has suggested that QTc interval prolongation may occur in some patients receiving the related narcotic sufentanil. Another report has implicated fentanyl as a potential cause of pulsus alternans in a patient with aortic stenosis and congestive heart failure.
Nevertheless, fentanyl has been advocated by some as a satisfactory agent for coronary artery surgery.[Ref]
Very common (10% or more): Nausea (18%), vomiting (10%), constipation
Common (1% to 10%): Dry mouth, abdominal distension, gastritis, dysphagia, dyspepsia, gastroesophageal reflux disease, ascites, hematemesis, taste perversion, abdominal pain, dehydration, anorexia, cachexia, vomiting, dry mouth, mouth ulcers/stomatitis, tongue edema
Uncommon (0.1% to 1%): Abdomen enlarged, flatulence
Rare (less than 0.1%): Choledochoduodenal sphincter spasm
Frequency not reported: Diarrhea
Postmarketing reports: Ileus, dental caries, tooth loss, gingival recession, gingivitis, gingival bleeding, lip edema, pharyngeal edema, gum bleeding, ulcer[Ref]
Uncommon (0.1% to 1%): Urinary retention
Very rare (less than 0.01%): Priapism
Very common(10% or more): Iontophoretic transdermal system: Application site reaction-Erythema (14%)
Common (1% to 10%): Application site irritation, pruritus
Uncommon (0.1% to 1%): Hyperhidrosis, rash
Rare (less than 0.1%): Systemic rashes
Frequency not reported: vesicles, papules/pustules, dry and flaky skin, vesiculobullous rash wound site oozing/bleeding, wound site inflammation/erythema
Postmarketing reports: Application site discharge, application site bleeding, application site infection, rash and scab, erosion, hyperesthesia, application site necrosis[Ref]
Approximately 60% of patients had some redness at the skin site 24-hours after removal of the iontophoretic transdermal system. The majority of skin events were categorized as mild, erythema and papules were observed; 2 patients had hyperpigmentation at the application site lasting 2 to 3 weeks; 3 patients had a rectangular mark at the application site which persisted for up to 3 months.[Ref]
Rare (less than 0.1%): Anaphylaxis[Ref]
The hemolysis observed may have been related to rapid injection of large volumes of hypotonic fentanyl solution. The authors therefore recommend slower injection rates and/or mixture in isotonic fluid.[Ref]
Common (1% to 10%): Anemia, neutropenia, lymphadenopathy, thrombocytopenia, leukopenia, aspartate aminotransferase increased, blood alkaline phosphatase increased, blood glucose increased, blood lactate increased, hypoalbuminemia, vasodilation[Ref]
Very rare (less than 0.01%): Recurrent herpes simplex infection following epidural administration[Ref]
Very rare (less than 0.01%): Syndrome of inappropriate antidiuretic hormone
Frequency not reported: abnormal healing, dehydration[Ref]
Uncommon (0.1% to 1%): Hot flush[Ref]
Common (1% to 10%): Fall/accidental injury, back pain, arthralgia, joint swelling, muscular weakness, myoclonus, involuntary muscle contractions, muscle rigidity (involving the respiratory musculature including the glottis)
Frequency not reported: Leg cramps, myalgia
Postmarketing reports: Abnormal gait/incoordination[Ref]
Uncommon (0.1% to 1%): Vision blurred, dry eye
Rare (less than 0.1%): Abnormal vision[Ref]
Common (1% to 10%): Depression, confusional state, hallucination, insomnia
Uncommon (0.1% to 1%): Anxiety, agitation, restlessness, agitation, disorientation, abnormal dreams, depersonalization, depression, emotional lability, euphoria, delirium
Frequency not reported: Nervousness[Ref]
Common (1% to 10%): Dyspnea, rhinitis, yawning, respiratory distress, apnea, bradypnea, hypoventilation, respiratory depression
Uncommon (0.1% to 1%): Cough, increased bronchial secretion, dysphonia, pharyngolaryngeal pain, wheezing, hypoxia, exertional dyspnea
Very rare (less than 0.01%): Acute noncardiogenic pulmonary edema
Frequency not reported: Asthma, hiccup, atelectasis, hyperventilation
Postmarketing reports: Respiratory arrest[Ref]
Frequently asked questions
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Related treatment guides
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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.