Psoriasis and Irritable Bowel Syndrome Risk
Yes, patients with psoriasis are at significantly increased risk of developing irritable bowel syndrome (IBS), with a 24% higher risk compared to matched controls, though the association is substantially stronger with inflammatory bowel disease (IBD) than with IBS specifically. 1
Magnitude of Risk
The most recent high-quality evidence demonstrates that psoriasis patients face elevated gastrointestinal disease risk across multiple conditions:
IBS risk is increased by 24% (HR 1.244,95% CI 1.168-1.325) over 15-year follow-up in a large matched cohort study of over 256,000 psoriasis patients. 1
The risk is higher in certain subgroups: women (HR 1.291) and patients ≥65 years (HR 1.325) show particularly elevated IBS risk. 1
IBD carries substantially higher risk than IBS: Crohn's disease risk is increased 2.5-fold (prevalence ratio 2.49) and ulcerative colitis risk is increased 1.7-fold (prevalence ratio 1.64-1.91) compared to the general population. 2, 3
Clinical Implications for Screening
All psoriasis patients should be informed about their increased risk of gastrointestinal disorders, including both IBD and IBS. 2
Red-Flag Symptoms Requiring Gastroenterology Referral
Screen for these specific symptoms that warrant immediate specialist evaluation: 2, 3
- Chronic diarrhea lasting ≥3 months
- Nocturnal bowel movements that awaken the patient from sleep
- Rectal bleeding (non-hemorrhoidal)
- Chronic abdominal pain
- Perianal fistula or abscess
- Unintentional weight loss
Prevalence of GI Symptoms
Psoriasis patients demonstrate significantly higher prevalence of all gastrointestinal symptoms compared to controls, including belly pain, bloating, diarrhea, mucus in stool, blood in stool, and weight loss. 4 This prevalence increases further in patients with more severe psoriasis or concomitant psoriatic arthritis. 4
Risk Stratification by Disease Severity
Patients with psoriatic arthritis, particularly those with axial involvement, have higher incidence and prevalence of IBD than those with skin-only psoriasis. 2 The presence of psoriatic arthritis should heighten clinical suspicion for gastrointestinal comorbidity. 5
Bidirectional Causal Relationship
Evidence suggests a bidirectional causal relationship between psoriasis and Crohn's disease specifically (OR 1.350 for psoriasis causing Crohn's; OR 1.425 for Crohn's causing psoriasis), though this relationship does not extend to ulcerative colitis in the same manner. 6 This shared pathophysiology likely reflects common immunopathogenic mechanisms involving systemic inflammation. 4, 7
Treatment Considerations
When selecting systemic therapy for psoriasis patients with gastrointestinal symptoms:
IL-17 inhibitors (secukinumab, brodalumab, ixekizumab) must be strictly avoided in patients with known or suspected IBD, as they can exacerbate Crohn's disease. 2, 3
TNF inhibitors (adalimumab, infliximab) or IL-12/23 inhibitors (ustekinumab) are preferred when both psoriasis and IBD coexist, as these agents treat both conditions effectively. 3
Common Pitfalls
The key clinical error is failing to distinguish between IBS and IBD in psoriasis patients. While IBS risk is modestly elevated (24% increase), IBD risk is dramatically higher (150-250% increase for Crohn's disease). 2, 3, 1 Any alarm symptoms listed above should trigger IBD evaluation rather than presumptive IBS diagnosis, as missing IBD has far greater implications for morbidity and mortality. 2