Side effects

Alfentanil may cause side effects. Tell your health care provider if any of these symptoms are severe or do not go away:

• upset stomach
• vomiting
• drowsiness
• unsteadiness and confusion
• constipation
• decreased appetite
• dry mouth
• difficultly urinating
• sweating

If you experience any of the following symptoms, call your health care provider immediately:

• unsteadiness
• difficulty breathing
• hallucinations
• difficulty being roused
• seizures

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online at http://www.fda.gov/MedWatch/report.htm or by phone 1-800-332-1088.