Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) causing inflammation anywhere along the digestive tract. Although often associated with diarrhea, constipation—defined as fewer than three bowel movements per week or passing hard, dry stools—can occur and may signal a serious complication.
Pathological Causes Specific to Crohn’s
The inflammation characteristic of Crohn’s disease leads to structural changes that physically impede stool passage. Chronic inflammation and subsequent healing cause the intestinal wall to thicken and scar, leading to a narrowing called a stricture. Strictures act as physical roadblocks, slowing or completely obstructing the movement of digested food and stool.
Constipation also results from the disease’s effects on intestinal motility, the normal muscle contraction (peristalsis) that moves waste through the gut. Active inflammation in a bowel segment can disrupt these coordinated contractions necessary for efficient transit. If the disease affects the rectum (proctitis), inflammation may interfere with nerve signals that trigger the urge to defecate, causing functional constipation.
Another internal factor is the formation of adhesions, bands of scar tissue that form outside the bowel, often after surgery or inflammation. These fibrous bands can tether loops of the intestine together or stick them to the abdominal wall, restricting natural movement. This restriction slows transit time and can result in chronic constipation.
Contributing Factors and Medications
Pain management often involves opioid-based medications, such as codeine or morphine, which slow gut motility. Opioids inhibit peristalsis and increase water absorption from the stool, resulting in hard, dry feces.
Dietary choices made to manage CD symptoms can inadvertently cause constipation. Many patients restrict high-fiber foods to avoid discomfort during a flare-up, but this lack of bulk prevents healthy stool formation. Inadequate fluid intake, especially following chronic diarrhea, causes dehydration and results in harder stools that are difficult to pass.
Patients experiencing pain during or after a bowel movement, often due to perianal complications like fissures, may consciously avoid defecating. This voluntary withholding allows more water to be absorbed, compounding constipation and creating a cycle of pain avoidance. Non-opioid medications, including iron supplements for CD-related anemia and some antidepressants, also list constipation as a side effect.
Targeted Management and Warning Signs
Management of constipation in Crohn’s disease must begin with a medical consultation to determine the underlying cause. This is crucial because if a stricture is present, using laxatives or increasing fiber intake can be dangerous and potentially lead to a complete bowel obstruction. A healthcare provider must rule out a physical blockage before recommending treatment.
For cases not involving a stricture, the safest treatments are stool softeners and osmotic laxatives. Osmotic agents, such as polyethylene glycol, draw water into the intestine, softening the stool and making it easier to pass. These are preferred over stimulant laxatives, which can cause cramping and dehydration.
Patients must be cautious with bulk-forming agents, like psyllium, as these supplements can swell and become lodged in a narrowed section of the bowel. Dietary changes should involve a gradual increase in soluble fiber and adequate hydration. Severe or sudden constipation accompanied by red flag symptoms requires immediate emergency medical attention, as it signals a life-threatening intestinal obstruction. Warning signs include severe abdominal pain, persistent vomiting, and the inability to pass gas or stool.