Alfentanil Side Effects Center

Last updated on RxList: 10/19/2022
Alfentanil Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Alfentanil?

Alfentanil HCl Injection is an opioid analgesic (pain reliever) indicated as an analgesic adjunct given in incremental doses in the maintenance of anesthesia with barbiturate/nitrous oxide/oxygen; as an analgesic administered by continuous infusion with nitrous oxide/oxygen in the maintenance of general anesthesia; as a primary anesthetic agent for the induction of anesthesia in patients undergoing general surgery in which endotracheal intubation and mechanical ventilation are required; and as the analgesic component for monitored anesthesia care (MAC). Alfentanil is available in generic form.

What Are Side Effects of Alfentanil?

Alfentanil may cause serious side effects including:

  • hives,
  • difficulty breathing,
  • swelling of your face, lips, tongue, or throat,
  • blurred vision,
  • chest pain or pressure,
  • confusion,
  • dizziness,
  • fainting,
  • lightheadedness,
  • fast, slow, or irregular heartbeat,
  • pounding pulse,
  • headache,
  • fast or shallow breathing,
  • nervousness,
  • breathing that stops,
  • pale or blue lips, fingernails, or skin,
  • pounding in the ears,
  • sweating,
  • unusual tiredness,
  • weakness,
  • cough,
  • noisy breathing,
  • rigid or stiffness of the neck, arms, and legs,
  • tightness in the chest,
  • agitation,
  • cough,
  • darkening of the skin,
  • diarrhea,
  • trouble swallowing,
  • fever,
  • itching,
  • skin rash,
  • loss of appetite,
  • nausea,
  • overactive reflexes,
  • poor coordination,
  • restlessness,
  • shivering,
  • sweating,
  • talking or acting with excitement you cannot control,
  • trembling,
  • twitching, and
  • vomiting

Get medical help right away, if you have any of the symptoms listed above.

Common side effects of alfentanil include:

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Alfentanil

The dosage of alfentanil HCl injection is individualized and adjusted to the desired effect in each patient according to body weight, physical status, underlying pathological condition, use of other drugs, and type and duration of surgical procedure and anesthesia.

What Drugs, Substances, or Supplements Interact with Alfentanil?

Alfentanil may interact with other CNS depressants (such as barbiturates, tranquilizers, opioids, or inhalation general anesthetics), erythromycin, cimetidine, and drugs affecting hepatic blood flow or enzyme function. Tell your doctor all medications and supplements you use.

Alfentanil During Pregnancy or Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using alfentanil; it is unknown how it might affect a fetus. Alfentanil passes into breast milk. Consult your doctor before breastfeeding. Withdrawal symptoms may occur if you suddenly stop taking alfentanil.

Additional Information

Our Alfentanil HCl Injection Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Back Pain: 16 Back Pain Truths and Myths See Slideshow
Alfentanil Professional Information


The most common adverse reactions of opioids are respiratory depression and skeletal muscle rigidity, particularly of the truncal muscles. Alfentanil may produce muscular rigidity that involves the skeletal muscles of the neck and extremities. See CLINICAL PHARMACOLOGY, WARNINGS, and PRECAUTIONS on the management of respiratory depression and skeletal muscle rigidity.

The adverse experience profile from 696 patients receiving alfentanil for Monitored Anesthesia Care (MAC) is similar to the profile established with alfentanil during general anesthesia. Respiratory events reported during MAC included hypoxia, apnea, and bradypnea. Other adverse events reported by patients receiving alfentanil for MAC, in order of decreasing frequency, were nausea, hypotension, vomiting, pruritus, confusion, somnolence and agitation.

The following adverse reaction information is derived from controlled and open clinical trials in 785 patients who received intravenous alfentanil during induction and maintenance of general anesthesia. The controlled trials included treatment comparisons with fentanyl, thiopental sodium, enflurane, saline placebo and halothane. The incidence of certain side effects is influenced by the type of use, e.g., chest wall rigidity has a higher reported incidence in clinical trials of alfentanil induction, and by the type of surgery, e.g., nausea and vomiting have a higher reported incidence in patients undergoing gynecologic surgery. The overall reports of nausea and vomiting with alfentanil were comparable to fentanyl.

Incidence Greater than 1% - Probably Causally Related (Derived from clinical trials)

Gastrointestinal: nausea (28%), vomiting (18%)

Cardiovascular: arrhythmia, bradycardia (14%), hypertension (18%), hypotension (10%), tachycardia (12%)

Musculoskeletal: chest wall rigidity (17%), skeletal muscle movements*

Respiratory: apnea*, postoperative respiratory depression

Central Nervous System: blurred vision, dizziness*, sleepiness/postoperative sedation

*Incidence 3% to 9% All others 1% to 3%

Incidence Less than 1% - Probably Causally Related (Derived from clinical trials)

Adverse events reported in post-marketing surveillance, not seen in clinical trials, are italicized.

Body as a whole: anaphylaxis

Central Nervous System: headache*, myoclonic movements, postoperative confusion*, postoperative euphoria*, shivering*

Dermatological: itching*, urticaria*

Injection Site: pain*

Musculoskeletal: skeletal muscle rigidity of neck and extremities

Respiratory: bronchospasm, hypercarbia*, laryngospasm*

*Incidence 0.3% to 1%

Drug Abuse And Dependence

Alfentanil is a Schedule II controlled drug substance that can produce drug dependence of the morphine type and therefore has the potential for being abused.

Opioid analgesics have been associated with abuse and dependence in health care providers and others with ready access to such drugs. Alfentanil should be handled accordingly.

Read the entire FDA prescribing information for Alfentanil (alfentanil)


Medically speaking, the term "myalgia" refers to what type of pain? See Answer

© Alfentanil Patient Information is supplied by Cerner Multum, Inc. and Alfentanil Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

Health Solutions From Our Sponsors