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Alfenta Side Effects

Generic Name: alfentanil

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

For the Consumer

Applies to alfentanil: intravenous solution

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

If any of the following side effects occur while taking alfentanil, check with your doctor or nurse immediately:

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

Minor Side Effects

Some of the side effects that can occur with alfentanil 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:
  • 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.

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

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.