It’s tough enough to have pain severe enough to be treated with opioid pain medications like Vicodin or Oxycontin—but the side effects can make things even more difficult. Constipation from taking opioid medications can be debilitating and is estimated to affect 40 – 86% of patients using these drugs.
Why do opioids cause constipation?
Constipation from opioid pain meds occurs because of how these medications work. Opioids relieve pain due to direct effects on µ-opioid receptors, which is how they can relieve pain—but these receptors are also plentiful throughout the GI tract (your digestive system). This means a slower transit time through the gut, increased fluid absorption (harder stools) and increased sphincter tone.
What should I do first on my own, before I ask my doctor for help?
Start with dietary measures like more water and fiber, increased physical activity, and over-the-counter laxatives. Laxatives recommended as first-line therapy for opioid induced constipation include stimulant laxatives like Senna, Dulcolax (bisacodyl), or Cascara. There is insufficient evidence from clinical trials to recommend one over another, so pick one to see if it will work for you.
What won’t work?
For opioid induced constipation, bulk forming agents won’t work and may cause more discomfort. Bulk forming agents include psyllium, Metamucil, Citrucel, or Fibercon. These act to increase stool bulk and stimulate peristalsis—movements that push stuff through the colon. Not only will these options not help with opioid induced constipation (because opioids prevent peristalsis) but they may result in worse abdominal pain.
Over the counter options didn’t work, now what?
At this point, see your doctor. Constipation that doesn’t respond to the OTC options above needs the help of your physician. Your doctor may prescribe osmotic agents (eg, polyethylene glycol, lactulose), or newer prescription medications.
What are the “big guns”—the newer prescriptions?
- Amitiza (lubiprostone). Amitiza is a prokinetic, meaning it stimulates motility. It is a prescription medication for constipation that stimulates chloride channels and promotes intestinal fluid secretion. This adds fluid to stool and speeds up travel time through the gut, improving symptoms of constipation.
- Movantik (naloxegol). The newest kid on the block, Movantik, blocks the effects of opioids on the gut and works well in folks who have not responded to laxatives.
- Relistor (methylnaltrexone). Though effective and approved for opioid induced constipation, Relistor is an injection. Given newer pill options, Relistor may be phased out. Relistor is a subcutaneous injection given once every other day or every third day.
Hope this helps.