Alfentanil Side Effects

Medically reviewed by Drugs.com. Last updated on Feb 5, 2025.

Applies to alfentanil: intravenous solution.

Precautions

Your doctor will check your progress closely while you or your child are receiving this medicine. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to receive it.

This medicine may cause allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Call your doctor right away if you or your child have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Check with your doctor before using this medicine with alcohol or other medicines that affect the central nervous system (CNS). The use of alcohol or other medicines that affect the CNS with alfentanil may worsen the side effects of this medicine, such as dizziness, poor concentration, drowsiness, unusual dreams, and trouble with sleeping. Some examples of medicines that affect the CNS are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicines, medicine for depression, medicine for anxiety, prescription pain medicine or narcotics, medicine for attention deficit and hyperactivity disorder, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics.

This medicine may cause sleep-related breathing problems (eg, sleep apnea, sleep-related hypoxemia). Your doctor may decrease your dose if you have sleep apnea (stop breathing for short periods during sleep) while using this medicine.

This medicine may make you dizzy, drowsy, or lightheaded. Do not drive or do anything else that could be dangerous until you know how this medicine affects you. Sit or lie down if you feel dizzy. Stand up carefully.

Tell your doctor if you or your child have stiffness in the muscles of your neck, chest, hands, or legs after receiving this medicine.

Check with your doctor right away if you or your child have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. Your risk may be higher if you also take certain other medicines that affect serotonin levels in your body.

This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.

Using narcotics for a long time can cause severe constipation. To prevent this, your doctor may direct you to take laxatives, drink a lot of fluids, or increase the amount of fiber in your diet. Be sure to follow the directions carefully, because continuing constipation can lead to more serious problems.

Using this medicine while you are pregnant may cause neonatal withdrawal syndrome in your newborn babies. Tell your doctor right away if your baby has an abnormal sleep pattern, diarrhea, a high-pitched cry, irritability, shakiness or tremors, weight loss, vomiting, or fails to gain weight.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of alfentanil

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:

Other side effects of alfentanil

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:

For healthcare professionals

Applies to alfentanil: injectable solution.

General adverse events

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

Respiratory

• 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]

Hypersensitivity

• Postmarketing reports: Anaphylaxis^[Ref]

Cardiovascular

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

Musculoskeletal

• 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]

Psychiatric

• 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]

Gastrointestinal

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

Dermatologic

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

Local

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

Endocrine

Opioids:

• Postmarketing reports: Adrenal insufficiency, androgen deficiency^[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]

Genitourinary

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

Ocular

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

Other

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

See also:

Further information

Alfentanil side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer