IBS Constipation Treatment: Gut-Brain Axis in Primary Care

Primary Care IBS: A Focus on Constipation and the Gut-Brain Connection

A 2026 study from KU Leuven in Belgium analyzed nearly 500 adults newly diagnosed with irritable bowel syndrome (IBS) in primary care. While 70% met formal diagnostic criteria, the research highlights distinct clinical profiles, particularly for the constipation subtype (IBS-C). The findings point to a complex interaction between physical symptoms and mental health, suggesting IBS-C management requires more than just laxatives.

Primary Care IBS: Underdiagnosis and High Symptom Burden

Led by researcher R. Wils at the TARGID center, the DOMINO study analysis provides a rare look at IBS in a real-world primary care setting. A key finding is that 30% of patients diagnosed by their general practitioner did not meet the strict Rome IV diagnostic criteria. This gap suggests overdiagnosis, underdiagnosis of other conditions, or a different illness perception between doctors and specialists.

More striking is the symptom severity. Using the IBS Severity Scoring System (IBS-SSS), where scores above 175 indicate moderate disease, the average score was 268. Severe symptoms (scores above 300) were present in 36% of patients. This contradicts the outdated notion that IBS in primary care is a mild condition. The study confirms these patients experience significant daily disruption. Symptom severity was significantly higher in patients who did meet the Rome IV criteria, indicating this group has a more definitively classifiable and impactful form of the disorder.

IBS-C is Less Common but Psychosocial Comorbidity is High in Mixed Subtype

Stool subtype distribution revealed IBS-C as the least common, affecting 20% of the cohort. Diarrhea-predominant (IBS-D) and mixed (IBS-M) subtypes were more common at 33% and 31%, respectively. This challenges assumptions about subtype frequency in primary care and may influence diagnostic considerations.

The team, including gastroenterologist Jan Tack, found important differences in psychosocial health. Patients with IBS-M scored significantly higher on measures of somatic symptom disorder, depression (PHQ-9), and anxiety (GAD-7) compared to those with unclassified IBS. This aligns with other research on the gut-brain link in IBS subtypes. While IBS-C participants had high symptom scores, the data specifically flags IBS-M as a subtype with pronounced psychological comorbidity, suggesting its management is particularly complex.

Implications for Managing IBS with Constipation

For the 1 in 5 primary care IBS patients with constipation, these findings have direct implications. First, symptom severity is often high, warranting proactive treatment. Second, while the study didn’t find IBS-C to have the highest depression scores, the overall link between Rome-positive diagnosis and worse psychosocial health underscores a bidirectional gut-brain relationship. Constipation and abdominal pain can increase stress and anxiety, which in turn can slow gut motility and heighten pain perception via the gut-brain axis.

This means standard over-the-counter laxatives, which only address stool passage, are often insufficient. Effective management must also target visceral hypersensitivity and brain-gut communication. This mechanistic understanding supports the use of gut-brain neuromodulators, certain antidepressants, and mind-body therapies as part of a comprehensive plan. Research into compounds like linaclotide and tenapanor shows how modern treatments work by both drawing water into the intestine and reducing pain signals.

Moving Toward Integrated IBS-C Care in Primary Care

This analysis confirms that primary care physicians are on the front lines of IBS management. For IBS-C, a practical application is to routinely assess symptom severity and screen for anxiety and depression using simple questionnaires like the PHQ-9. Treatment should be stratified: moderate IBS-C may start with osmotic laxatives like polyethylene glycol or magnesium, while severe or refractory cases likely need prescription secretagogues (linaclotide, lubiprostone, plecanatide) or neuromodulators.

Given the gut-brain findings, non-pharmacological strategies are essential. A referral for gut-directed hypnotherapy or cognitive behavioral therapy should be considered early. Dietary approaches, particularly a structured low-FODMAP diet guided by a dietitian, can reduce fermentable sugars that cause gas, pain, and motility issues. Supporting the gut microbiome with polyphenols and possibly specific probiotics may also modulate the underlying environment. This integrated approach addresses the multiple mechanisms—motility, sensation, inflammation, and brain-gut interaction—that drive IBS-C.

Frequently Asked Questions

Is IBS in primary care usually a mild condition?

No. The DOMINO study found over 80% of primary care IBS patients had moderate or severe symptoms, with an average severity score far above the threshold for moderate disease, indicating it is a serious health issue.

What does it mean if my IBS is “Rome-positive”?

Meeting the Rome IV criteria means your symptom pattern aligns with the international standard for diagnosing IBS. The study found Rome-positive patients had significantly worse symptoms, lower quality of life, and more anxiety and depression than those who did not meet all criteria.

Why is the mixed IBS subtype (IBS-M) linked to more anxiety?

The unpredictable alternation between constipation and diarrhea in IBS-M may create greater distress and loss of control, exacerbating anxiety. The gut-brain axis is a two-way street; stress worsens gut symptoms, and severe, fluctuating gut symptoms increase psychological distress.

If I have IBS-C, should I just take a laxative?

While laxatives can help with stool passage, they often don’t relieve the abdominal pain and bloating of IBS-C. Because the condition involves disrupted gut-brain communication, effective management typically requires a combination of treatments targeting motility, pain, and stress.

Sources:
https://pubmed.ncbi.nlm.nih.gov/42663160/