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Alfentanil Side Effects

In Summary

Commonly reported side effects of alfentanil include: bradycardia, hypotension, and respiratory depression. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to alfentanil: intravenous solution

Along with its needed effects, alfentanil 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 or nurse immediately if any of the following side effects occur while taking alfentanil:

More common
  • Blurred vision
  • chest pain or discomfort
  • confusion
  • difficult or troubled breathing
  • dizziness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • fainting
  • fast, slow, pounding, or irregular heartbeat or pulse
  • headache
  • irregular, fast or slow, or shallow breathing
  • lightheadedness, dizziness, or fainting
  • nervousness
  • not breathing
  • pale or blue lips, fingernails, or skin
  • pounding in the ears
  • sweating
  • trouble breathing
  • unusual tiredness or weakness
  • Cough
  • noisy breathing
  • rigid muscles of the neck, arms, and legs
  • tightness in the chest
Incidence not known
  • Agitation
  • cough
  • darkening of the skin
  • diarrhea
  • difficulty with swallowing
  • fainting
  • fever
  • hives, itching, or skin rash
  • loss of appetite
  • nausea
  • overactive reflexes
  • poor coordination
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • restlessness
  • shivering
  • sweating
  • talking or acting with excitement you cannot control
  • trembling or shaking
  • twitching
  • vomiting

Some side effects of alfentanil 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:

More common
  • Drowsiness
  • sleepiness
  • False or unusual sense of well-being

For Healthcare Professionals

Applies to alfentanil: injectable solution


The most commonly reported adverse reactions include apnea, rigidity, and bradycardia.[Ref]


Common (1% to 10%): Apnea
Uncommon (0.1% to 1%): Hypercarbia, laryngospasm
Frequency not reported: Life-threatening respiratory depression, postoperative respiratory depression, bronchospasm, hypoxia, bradypnea, hiccups, hypercapnia, epistaxis, airway complication of anesthesia, endotracheal intubation complication
Postmarketing reports: Respiratory arrest, cough[Ref]


Postmarketing reports: Anaphylaxis[Ref]


Very common (10% or more): Arrhythmia, bradycardia (14%), hypertension (18%), hypotension (18%), tachycardia (12%)
Frequency not reported: Asystole
Postmarketing reports: Cardiac arrest[Ref]


Very common (10% or more): Chest wall rigidity (17%),
Common (1% to 10%): Skeletal muscle movements, muscle rigidity
Uncommon (0.1% to 1%): Skeletal muscle rigidity of neck and extremities[Ref]

Nervous system

Common (1% to 10%): Dizziness, movement disorders, dyskinesia
Uncommon (0.1% to 1%): Headache
Frequency not reported: Serotonin syndrome, seizures, sleepiness/postoperative sedation, somnolence, neurological anesthetic complication
Postmarketing reports: Myoclonic movements[Ref]


Common (1% to 10%): Euphoric mood
Uncommon (0.1% to 1%): Postoperative confusion, postoperative euphoria, excitation
Frequency not reported: Addiction abuse, misuse, agitation, crying
Postmarketing reports: Disorientation[Ref]


Very common (10% or more): Nausea (28%), vomiting (18%)[Ref]


Uncommon (0.1% to 1%): Itching, urticaria
Frequency not reported: Pruritus, allergic dermatitis, hyperhidrosis
Postmarketing reports: Erythema, rash[Ref]


Common (1% to 10%): Injection site pain[Ref]


Adrenal insufficiency has been reported with opioid use, more often following greater than 1 month of use. Androgen deficiency has occurred with chronic use of opioids.[Ref]

Postmarketing reports: Adrenal insufficiency, androgen deficiency[Ref]


Uncommon (0.1% to 1%): Urinary retention[Ref]


Common (1% to 10%): Visual disturbance
Frequency not reported: Blurred vision
Postmarketing reports: Miosis[Ref]


Common (1% to 10%): Fatigue, chills
Uncommon (0.1% to 1%): Shivering
Postmarketing reports: Pyrexia[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Alfentanil Hydrochloride (alfentanil)." Akorn Inc, Buffalo Grove, IL.

Some side effects of alfentanil may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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