Abstral Side Effects

Generic Name: fentanyl

Note: This page contains information about the side effects of fentanyl. Some of the dosage forms included on this document may not apply to the brand name Abstral.

Not all side effects for Abstral may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to fentanyl: film, lozenge/troche, spray, tablet

In addition to its needed effects, some unwanted effects may be caused by fentanyl (the active ingredient contained in Abstral). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking fentanyl:

More common
  • Black, tarry stools
  • blurred vision
  • chest pain
  • confusion
  • convulsions
  • cough
  • decreased urine
  • difficult or labored breathing
  • dizziness
  • dry mouth
  • fainting
  • fever or chills
  • increased thirst
  • irregular heartbeat
  • lightheadedness
  • loss of appetite
  • lower back or side pain
  • mood changes
  • muscle pain or cramps
  • nausea or vomiting
  • nervousness
  • numbness or tingling in the hands, feet, or lips
  • painful or difficult urination
  • pale skin
  • pounding in the ears
  • rapid breathing
  • sneezing
  • 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
Less common
  • Abdominal or stomach pain
  • change in walking and balance
  • clumsiness or unsteadiness
  • decreased awareness or responsiveness
  • decreased frequency of urination
  • headache
  • muscle twitching or jerking
  • pounding in the ears
  • rhythmic movement of the muscles
  • seeing, hearing, or feeling things that are not there
  • seizures
  • 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

If any of the following symptoms of overdose occur while taking fentanyl, get emergency help immediately:

Symptoms of overdose
  • Extremely shallow or slow breathing

Some of the side effects that can occur with fentanyl may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Back pain
  • diarrhea
  • difficulty having a bowel movement (stool)
  • difficulty with moving
  • discouragement
  • feeling sad or empty
  • irritability
  • lack or loss of strength
  • loss of interest or pleasure
  • muscle stiffness
  • pain in the joints
  • sleepiness or unusual drowsiness
  • tiredness
  • trouble concentrating
  • trouble sleeping
  • weight loss
Less common
  • 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
  • rash
  • sensation of spinning
  • sweating
Incidence not known
  • Tooth pain
  • trouble with gums
  • trouble with teeth

After you stop taking this drug, it is possible that you may still experience side effects that need medical attention. If you notice any of the following side effects check with your doctor immediately:

  • Restlessness
  • speech disorder
  • stomach cramps
  • weakness

For Healthcare Professionals

Applies to fentanyl: buccal film, buccal tablet, compounding powder, injectable solution, nasal spray, oral lozenge, oral transmucosal lozenge, sublingual spray, sublingual tablet, transdermal device, transdermal film extended release

Nervous system

Nervous system side effects have included mental and respiratory depression (particularly in the elderly), stupor, delirium, somnolence, and dysphoria. Muscle rigidity (involving the respiratory musculature including the glottis) may also occur and further aggravate the respiratory depression associated with fentanyl (the active ingredient contained in Abstral) therapy. Myoclonus has been reported with the use of transdermal therapy. A case of severe hemiplegic migraine attack precipitated by fentayl sedation has also been reported.

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.


Fentanyl shares the potential for abuse associated with other narcotic analgesics. Cases of inhalation of the contents of fentanyl (the active ingredient contained in Abstral) patches and oral ingestion of intravenous preparations have been reported.

Other side effects have included withdrawal symptoms (agitation, restlessness, anxiety, insomnia, tremor, abdominal cramps, blurred vision, vomiting, and sweating) after either abrupt cessation or fast tapering of narcotic analgesics.


Cardiovascular side effects have included hypotension, bradycardia, and arrhythmias rarely.

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.


Gastrointestinal side effects including nausea, vomiting, and constipation have been reported to have occurred commonly. Dental decay of varying severity including dental caries, tooth loss, and gum line erosion have been reported. Choledochoduodenal sphincter spasm has been reported rarely.


Respiratory side effects have included respiratory depression which has been frequently observed with fentanyl (the active ingredient contained in Abstral) therapy and one case of acute noncardiogenic pulmonary edema. Coughing has been reported following fentanyl administration for anesthesia induction.


Genitourinary side effects including urinary retention have been reported for other narcotic analgesics. A case of priapism has been associated with fentanyl (the active ingredient contained in Abstral) anesthesia.


Dermatologic side effects have included pruritus which has been reported frequently. Localized rashes (associated with the use of transdermal fentanyl (the active ingredient contained in Abstral) patches) and, less commonly, systemic rashes have also been reported.


Hypersensitivity side effects including anaphylaxis have been reported rarely.


The hemolysis observed may have been related to rapid injection of large volumes of hypotonic fentanyl (the active ingredient contained in Abstral) solution. The authors therefore recommend slower injection rates and/or mixture in isotonic fluid.

Hematologic side effects have included one study which suggested that a small amount of hemolysis (of uncertain clinical significance) may occur in patients treated with fentanyl.


Immunologic side effects including a case of recurrent herpes simplex infection have been reported following epidural administration of fentanyl (the active ingredient contained in Abstral) Intravenous fentanyl has been reported to increase natural killer cell cytotoxicity and circulating CD16+ lymphocyte levels.


Metabolic side effects including a case of syndrome of inappropriate antidiuretic hormone have been reported.

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