Opioids are medications primarily prescribed for pain management. While effective, they commonly cause side effects, with constipation being one of the most frequent and bothersome. This is known as Opioid-Induced Constipation (OIC), a significant challenge for many undergoing opioid therapy.
How Opioids Affect the Digestive System
Opioids bind to mu-opioid receptors throughout the body, including the gastrointestinal tract. When activated in the gut, these receptors disrupt normal digestion and influence gut motility, the muscle contractions that move food and waste.
Opioid binding reduces peristalsis, the wave-like contractions that propel contents forward, causing waste to remain in the intestines longer. Opioids also decrease fluid secretion into the intestines and increase water absorption from stool, resulting in harder, drier stool that is difficult to pass.
Opioids can also increase anal sphincter tone and reduce rectal fullness sensation. These actions make it harder to initiate and complete a bowel movement, contributing to OIC. Unlike other opioid side effects, constipation often persists throughout therapy because the gut does not develop tolerance.
Identifying Opioid-Induced Constipation and Initial Steps
OIC is recognized by changes in bowel habits after starting opioids. Indicators include fewer than three bowel movements per week, straining, hard or dry stools, incomplete evacuation, abdominal bloating, or abdominal discomfort. These symptoms are directly linked to opioid use, distinguishing OIC from other forms of constipation.
OIC management often begins with lifestyle and dietary adjustments. Increase fluid intake to soften stool. Incorporate more fiber from fruits, vegetables, and whole grains to add bulk, making it easier to pass. Regular physical activity, if appropriate, can also stimulate bowel movements.
If lifestyle changes are insufficient, over-the-counter laxatives can be considered. Stool softeners (e.g., docusate) moisten stool. Osmotic laxatives (e.g., polyethylene glycol) draw water into intestines to soften stool. Stimulant laxatives (e.g., senna) encourage bowel contractions.
Professional Treatments for Opioid-Induced Constipation
If home remedies and OTC laxatives don’t provide relief or symptoms worsen, professional medical attention is necessary. Seek a doctor for severe abdominal pain, no bowel movement for several days, or alarm symptoms like unexplained weight loss or blood in stool. A healthcare provider can assess and rule out other potential causes.
For persistent or severe OIC, medical professionals may prescribe medications to counteract opioid effects in the gut. Peripherally acting mu-opioid receptor antagonists (PAMORAs) are a class of drugs that block opioid receptors in the gastrointestinal tract. This action helps restore normal bowel function without affecting the pain-relieving effects of opioids in the brain.
Other prescription laxatives or therapies may be considered based on individual needs. Treatment plans are individualized, considering OIC severity, other medical conditions, and current medications.