What Is Opioid-Induced Constipation?

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Opioid-induced constipation refers to constipation that is caused by taking opioid medications. Constipation occurs when bowel movements are infrequent or difficult to pass. Opioid-induced constipation is different from other forms of chronic constipation and requires specialized treatment. 

Other symptoms of opioid-induced constipation may include nausea, vomiting, bloating, and abdominal pain. Opioid-induced constipation is often treated both with medications and lifestyle changes. This article will provide an overview of opioid-induced constipation, including common symptoms, causes, and treatment options. 

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Opioid-Induced Constipation Symptoms

Opioid-induced constipation may start as soon as you begin taking opioid medications or it may develop slowly while taking these medications. Opioid drugs are medications used to treat acute or chronic pain. 

Common symptoms of opioid-induced constipation include:

Causes

Opioid-induced constipation is caused by changes in the gastrointestinal (GI) tract that occur because of opioid drugs. 

Opioid drugs affect the mu receptors in the gastrointestinal tract. The mu receptors control the contraction of the muscles in the GI tract, known as intestinal motility. When these receptors are activated by an opioid drug, intestinal motility significantly decreases. This causes the muscles to slow down and stop contracting. This leads to stool staying in the GI tract instead of being removed from the body. 

Mucosal secretions in the gastrointestinal tract are also affected. When the secretions decrease, the GI tract becomes dry, and stool cannot pass through as easily. This results in dry, bulky stool that stays in the GI tract. 

Opioids also lead to increased contraction of the anal sphincter. This is the muscle that helps to release stool from the body. When it is contracted, you may notice that it feels difficult to have a bowel movement. This leads to straining and may cause hemorrhoids.

Should I Avoid Opioids?

Because opioid drugs cause significant side effects, including constipation, it is important to use them as little as possible. The Centers for Disease Control and Prevention (CDC) developed clinical guidelines to help practitioners decide when to prescribe opioid medication and when to seek an alternative drug. The guidelines guide prescribers through setting treatment goals, considering the potential benefits and risks of treatment, and determining the most effective dosage. 

Evaluation and Diagnosis

Opioid-induced constipation is a relatively common problem and should be considered any time an individual takes opioid drugs. It’s estimated that up to 4% to 5% of the population in the United States regularly takes opioid drugs, and 40% to 80% of them experience opioid-induced constipation.

The first step in making a diagnosis is taking a thorough medical history. When you see your doctor, they will likely ask you about the frequency and consistency of your bowel movements. They will also ask if you have experienced pain or straining when having a bowel movement. 

According to the American Gastroenterological Association (AGA), opioid-induced constipation can be diagnosed using the Rome IV definition. The Rome Foundation is a not-for-profit organization that develops diagnostic criteria for gut disorders. According to the Rome Foundation, a person meets the criteria for opioid-induced constipation when they experience new or worsening constipation symptoms when starting or increasing opioid therapy and:

  • Strain during more than 25% of the time spent passing stool
  • Have hard or lumpy stools more than 25% of the time
  • Feel as though they are unable to fully empty all the stool 25% of the time
  • Notice the feeling of a blockage when trying to pass a stool
  • Require manual maneuvers to pass stool 25% of the time
  • Have fewer than three bowel movements per week

Barriers to Diagnosis

Opioid-induced constipation is a relatively common problem but still goes undiagnosed too often. A 2019 study found that barriers to diagnosis include:

  • Physicians’ lack of awareness of the problem
  • Patients feeling embarrassed about bringing it up
  • Doctors feeling uncomfortable asking about constipation
  • Lack of universal diagnostic guidelines
  • Lack of specific treatment plans

Treatment and Lifestyle Changes

Opioid-induced constipation usually does not improve on its own and requires treatment. 

Laxatives are medications used to make having a bowel movement easier and more comfortable. They are considered first-line treatment for opioid-induced constipation. Options include:

  • Stool softeners work by allowing water and lipids to enter the stool in the gastrointestinal tract. This softens the stool, making it easier to pass. Docusate sodium is a commonly used stool softener. 
  • Osmotic laxatives draw water into the gastrointestinal tract. This softens the stool and makes it easier to pass. Common examples include polyethylene glycol (PEG), magnesium hydroxide, magnesium citrate, and lactulose. 
  • Lubricants soften the stool by lubricating the lining of the gastrointestinal tract. This allows the stool to pass through the tract more easily. An example of a lubricant laxative is mineral oil. 
  • Stimulant laxatives stimulate the muscles in the gastrointestinal tract to contract and move stool out of the body. This is known as colonic motility. Examples include bisacodyl, sodium picosulfate, and senna. 

While laxatives are able to treat the symptoms of opioid-induced constipation, they do not cure the problem. In recent years, practitioners have begun to use new classes of drugs to treat opioid-induced constipation. These drugs are able to target the mu receptors directly and include:

  • Entereg (alvimopan)
  • Amitiza (lubiprostone)
  • Relistor (methylnaltrexone) 
  • Movantik (naloxegol)

Lifestyle changes that help to ease constipation include drinking more water, increasing physical activity, consuming fiber-rich foods, and using the toilet as soon as you feel the urge to go. While these lifestyle changes may help, they usually do not relieve opioid-induced constipation on their own.

Because of the physical changes taking place in the gastrointestinal tract, most individuals with opioid-induced constipation require laxative therapy. Enemas, a method used to cleanse the colon, are occasionally used as a last resort when other treatment options have not provided relief.

A Note on Fiber

Fiber is often thought of as an important part of preventing constipation. Fiber is a type of carbohydrate that cannot be digested by the body. Because it cannot be broken down in the gastrointestinal tract, it aids in the elimination of stool. While fiber can be helpful in preventing constipation, it should be used with caution in opioid-induced constipation. Because opioid-induced constipation causes dry, hard stools, adding more fiber to the diet may result in abdominal pain and cramping without providing any constipation relief. Any fiber supplement should be taken with plenty of water to ensure your body is able to comfortably pass stool. 

Prognosis

Opioid-induced constipation is caused by taking opioid medication and should resolve once the medication is stopped. Starting a laxative at the same time as starting opioid therapy has been found to improve or even prevent constipation.

If you will be starting or increasing the dose of opioids soon, talk with your doctor about taking a laxative medication. These drugs are able to relieve constipation and keep your bowel movements regular. 

Coping

To cope with opioid-induced constipation, talk with your doctor about starting regular laxative medication right away. Make sure you are drinking plenty of water and eating a healthy diet with fruits and vegetables. Ask your doctor about how many grams of fiber to aim for each day. Finally, be sure to use the toilet as soon as you feel the urge to have a bowel movement. 

Summary

Opioid-induced constipation is a common problem among those who take opioid drugs to treat their pain. Taking opioid medication leads to constipation because these drugs cause decreased motility and mucosal secretions in the gastrointestinal tract. This leads to hard, dry stools that are difficult or painful to pass. Treatment usually begins with laxative medications and lifestyle modifications such as drinking more water, exercising, and eating more fiber-rich foods. 

A Word From Verywell

Opioid-induced constipation is a frustrating and uncomfortable side effect of taking opioid drugs. Know that it is normal to experience constipation when taking pain medicines, and talk with your doctors about how to relieve your symptoms right away.

Starting a regular laxative when you begin a new opioid medication has been proven to be helpful in preventing constipation issues. Opioids affect how your gastrointestinal tract works, so don’t try to fix this with lifestyle changes alone. Talk with your doctor and get the support you need. 

Frequently Asked Questions

  • How common is opioid-induced constipation?

    Opioid-induced constipation is a common problem and affects up to 40% to 80% of individuals who take opioid medications. 

  • How do you prevent opioid-induced constipation?

    It can be difficult to prevent opioid-induced constipation. The most effective strategy is to begin taking laxatives as soon as you start the opioid medication. Talk with your doctor about which laxatives to take and the dose. In addition to medications, drink plenty of water and eat a healthy diet with fruits and vegetables. 

  • How is opioid-induced constipation treated?

    Opioid-induced constipation is treated with laxatives to soften the stool and increase motility in the gastrointestinal tract.

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6 Sources
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