Ulcerative Colitis (UC) is a chronic inflammatory bowel disease (IBD) causing inflammation and ulcers in the lining of the large intestine (colon and rectum). The most recognized symptom is typically bloody diarrhea, driven by inflammation accelerating waste movement. This common presentation makes constipation—the opposite problem—seem like a paradox. However, many people with UC experience a sluggish flow of stool, sometimes called ulcerative colitis-associated constipation syndrome (UCAC), which is a genuine concern for those managing the condition.
Constipation as a Direct Symptom of Ulcerative Colitis
Constipation in UC patients is frequently linked to the location of inflammation within the large intestine. When the disease is confined to the rectum (Ulcerative Proctitis), it can directly cause constipation symptoms. Intense inflammation in the rectum causes muscle spasms and increased sensitivity, resulting in tenesmus (the painful feeling of needing to pass stool when the bowel is empty).
This irritation also affects muscle coordination, leading to difficulty passing small, hard stools. Stool may be normal higher up but becomes desiccated and difficult to pass upon reaching the inflamed area. The inflammation itself can also damage the enteric nervous system, the complex network of nerves that controls the gut’s movement, disrupting the normal signals for muscle contractions.
This disruption can delay stool transit through the right side of the colon, even if inflammation is limited to the left side (“proximal constipation”). Chronic inflammation and healing can lead to scar tissue (a stricture) that narrows the intestinal passage and physically blocks stool flow. Constipation is more likely to affect people with left-sided or distal disease, suggesting proximity of inflammation to the end of the digestive tract plays a role.
Treatment and Lifestyle Factors Leading to Constipation
Constipation in UC is often a side effect of medical treatments and patient behavior, beyond the direct effects of inflammation. Medications used to manage the disease can significantly slow digestive tract movement. Opioid pain relievers, used for severe discomfort, decrease gut motility by binding to bowel receptors.
People with UC often develop anemia due to chronic blood loss, requiring iron supplements. Oral iron supplements can directly contribute to constipation by altering the gut microbiome and causing the intestinal lining to absorb more water, resulting in drier, harder stool. Some anti-inflammatory medications, such as 5-aminosalicylates (5-ASAs)—a common first-line treatment—may also cause constipation.
Lifestyle changes adopted by UC patients, often out of fear of triggering symptoms, can inadvertently cause constipation. Many restrict dietary fiber intake, believing it will irritate the inflamed bowel, but insufficient bulk leads to difficulty passing stool. Inadequate fluid intake, sometimes due to fear of increasing bowel movement urgency, contributes to dehydration, making stools hard and dry. Psychological factors, such as stress or delaying bowel movements to avoid pain, can train the bowel to retain stool, worsening the problem.
Management and When to Seek Medical Guidance
Managing constipation in UC requires a careful approach prioritizing gentle relief and coordination with a gastroenterologist. Increasing fluid intake is a simple first step, as proper hydration helps soften stool and makes it easier to pass. While coarse, insoluble fiber can be problematic, small, gradual increases in soluble fiber (found in foods like oats and certain fruits) may be beneficial because it creates less residue and helps normalize stool consistency.
Over-the-counter options should be selected with caution, favoring stool softeners or osmotic laxatives (like polyethylene glycol), which draw water into the colon. Stimulant laxatives, which force the colon to contract, should generally be avoided for chronic use as they can be harsh on an inflamed bowel. Regular, gentle physical activity stimulates the intestinal muscles, helping to improve peristalsis and gut function.
Immediate medical consultation is necessary if constipation is accompanied by severe abdominal pain, persistent vomiting, or significant abdominal swelling, as these may indicate a bowel obstruction or complication. Any suspicion of a stricture or development of new, concerning symptoms should prompt a discussion with the healthcare provider to ensure a safe and tailored management plan. It is particularly important to never stop prescribed UC medications or iron supplements without first consulting a physician.