Constipation. It’s not easy on the body, and it’s not easy to talk about, yet it’s an extremely common chronic side effect of opioid pain medications. So while you may be reading this article discreetly, hoping no one finds out about your bathroom blues, know that this inconvenient side effect is widespread among pain patients. Luckily, it’s treatable, after talking to your doctor about the right treatment. We’ll prepare you for your visit by answering some basic questions about opioid-induced constipation.


At least half of all patients on opioids (prescription drugs such as methadone, fentanyl, oxycodone, codeine and morphine) experience chronic constipation as a side effect, says Eugene R. Viscusi, MD, director of acute pain management, Department of Anesthesiology at Thomas Jefferson University in Philadelphia.

Not only does opioid intake increase your risk of chronic constipation, but your unique health condition may also up your risk. “Some patients, such as the elderly or those with compromised health, are at increased risk,” says Dr. Viscusi. “In addition, patients with poor or reduced physical activity, dehydrated patients or patients with reduced liquid intake seem to have more difficulty. It is easy to see how patients in the palliative care or hospice setting are at unique risk.”

In addition, other common medications that a person might take along with opioids can lead to constipation. Examples include antidepressants, antacids and blood pressure medications.


As mentioned above, constipation can have many causes. “I think of constipation as a multifactorial disease state,” says Dr.Viscusi. “It rarely has a single cause, although opioids can be the major driver.”

When opioids are the primary cause of constipation, it is because they tend to slow down the digestive system. In a healthy digestive system, the large intestine removes water from the stool as it passes through. When waste stays in the large intestine too long, too much water is removed, which leads to the hard, difficult-to-pass stools associated with constipation.

“Opioids work by their activity at specific receptors (mureceptors),” explains Dr. Viscusi. “The gut is lined with these receptors. When opioids attach to the mu receptors in the bowel, the result is a disruption in the normal forward propulsive movement of bowel activity, resulting in slowed bowel activity.”

The digestive sluggishness caused by opioids isn’t just an initial reaction on the part of the body. Unlike some side effects that go away after the first several weeks of usage, constipation is a long-term response that can stubbornly stick around for as long as the person takes opioids.

“Unlike other opioid-related side effects, such as nausea and vomiting, constipation never goes away,” says Dr. Viscusi. “This is one side effect for which patients do not develop tolerance with chronic exposure.”


Tammy Montgomery of Winston-Salem, North Carolina, is one of the many pain patients who suffer daily from opioid-induced constipation. It started, she says, when she began taking methadone for pain related to a brain aneurysm and surgery.

Initially, Montgomery was on 40 mg of methadone a day. “At that time, I had zero pain, but the constipation was unbearable,” she says. “I told my doctor that I wanted to gradually reduce my dosage to see if it would help.”

Now, Montgomery takes just 12 mg of methadone a day. In addition, she eats a high-fiber diet, drinks copious amounts of water, exercises and takes enemas as needed. It’s a combination she arrived at after years of miserable experimentation with laxatives, supplements and drugs, all of which made her unbearably nauseous. Although she still has some residual constipation, she says, “It’s not pleasant, but I could feel a lot worse.” Optimizing the dose of her medication and adjusting her diet has allowed her the pain relief she needed to regain a life she enjoys.

While Montgomery didn’t respond well to laxatives, many patients benefit from them. “Constipation is unpredictable, but most patients treated with opioids will benefit from some bowel regimen that includes laxatives,” says Dr. Viscusi.

Montgomery’s diet and activity level are right in line with medical recommendations for treating constipation. “Adequate hydration is critical, so taking lots of fluids is a good idea,” says Dr. Viscusi. “And since inactivity is a risk factor, regular physical activity is encouraged.”

Additionally, pain patients suffering from opioid-induced constipation have a possible pharmaceutical option. The FDA recently approved a drug called Relistor (methylnaltrexone) for this type of constipation when laxatives are ineffective. Relistor works against the response of the mu opioid receptors in the digestive system, selectively blocking constipation without blocking pain relief. Therefore, it helps normalize bowel function without interfering with pain treatment.

“Patients generally experience rapid bowel movement following administration of methylnaltrexone, which is injected by needle, usually within 30 minutes,” says Dr. Viscusi. “Unlike laxatives, this offers patients a relatively predictable timed response for bowel movement. And most patients describe the sensation to be like normal bowel activity. This can be a tremendous advantage.”


Living life with continual constipation is no walk in the park, but beyond the general distress it causes, you may experience additional complications if it goes untreated.

Lack of pain relief is a common side effect of opioid-induced constipation. Montgomery was able to successfully lower her opioid dosage and still get the pain relief she needed, but she did so under a pain doctor’s supervision. Patients who cut dosages on their own in their quest for constipation relief run the risk of poor pain management, says Dr. Viscusi.

Additionally, chronic constipation can lead to more severe colorectal problems. “Some patients become impacted with stool,” says Dr. Viscusi. “This may result in an uncomfortable and embarrassing visit to the ER for manual disimpaction. Many patients with chronic constipation also complain of significant pain with bowel movements, bleeding and anal fissures. Overtime, there may be changes to the bowel, such as chronic dilation of the colon from collection of stool.”


Before you can experience relief from your constipation, you have to talk to your doctor about the right treatments for you. This can be difficult for some people.

oic2“While many patients complain bitterly about constipation, there are also many who suffer in silence since they are embarrassed to discuss this,” says Dr. Viscusi. “Often, elderly patients will be more accepting of side effects and unwilling to discuss constipation unless specifically asked or questioned by family members.”

Montgomery, a singer and songwriter, is definitely not shy about discussing her problem. In fact, the outgoing musician wrote a song about it for a constipation focus group she participated in. The song, “Pop a Vain in Your Brain,” broke the ice and allowed the other participants in the group to feel more comfortable in sharing their individual stories.

“When you talk about it, you know it’s not just you who’s going through it,” says Montgomery. “Everyone in the group could relate to everything everyone else was saying.”

Montgomery also advocates being vocal with your doctor, particularly when it comes to adjusting the levels of your pain medication. “Work with your doctor to get your pain medication down to the lowest level you can while still treating your pain.”

Montgomery’s other recommendations include diet and exercise changes: “Get all of the good fiber and good food into your body that you can,” she says. “Throw on your tennis shoes and get out there and walk. If you don’t do anything else, walk every day. That helps quite a lot.

“Your mindset is important as well,” continues Montgomery. “You have to ask: ‘Am I going to let this beat me, or am I going to find something that works? {PP}

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