How long does Alvimopan take to work?
Last updated September 7, 2026.
**Alvimopan works gradually over several days rather than within hours, and in studies it helped bowel function return roughly a day sooner after surgery.** It is a hospital-only medicine used around bowel resection surgery to counter the gut-slowing effect of opioid pain medicine. The first dose is given 30 minutes to 5 hours before the operation, then 12 mg twice a day starting the day after, for up to 7 days or 15 total doses. You will not feel it kick in the way you feel a pain pill; the signal that it is working is passing gas, having a bowel movement, and keeping down solid food. Walking as soon as your team allows, sipping fluids, and using the smallest effective opioid dose all help your bowels restart. Alvimopan is not for home use and is not a treatment for everyday constipation.
What to do
- Expect days, not hours: Judge progress by passing gas and having a bowel movement, not by how you feel an hour after a dose.
- Keep the schedule: Doses are timed before surgery and twice daily after, and the course stops at 7 days or 15 doses.
- Move early: Short walks as soon as your care team clears you help the bowels restart faster than lying still.
- Limit opioids where you can: Ask about non-opioid pain options, since opioids are the main reason bowel function stalls after surgery.
- Report a stalled gut: Tell your team about vomiting, a swollen or painful belly, or no gas or stool several days out.
- Do not use it at home: Alvimopan is a short hospital course and is not a remedy for opioid-related constipation outside surgery.
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