From the Guidelines
The etiology of irritable bowel syndrome (IBS) is multifactorial, involving a complex interplay between gut-brain axis dysfunction, visceral hypersensitivity, altered gut motility, intestinal inflammation, and dysbiosis of the gut microbiome, as supported by recent studies 1.
Key Factors Contributing to IBS Etiology
- Psychological factors such as stress, anxiety, and depression can trigger or worsen symptoms through the gut-brain connection, with evidence suggesting a significant comorbidity between IBS and mental health disorders 1.
- Genetic predisposition appears to play a role, with family clustering observed in many cases, although specific genetic markers are still being researched.
- Post-infectious IBS can develop following gastroenteritis, particularly after bacterial infections like Campylobacter or Salmonella, highlighting the role of infectious agents in triggering IBS symptoms 1.
- Dietary factors, including FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), can trigger symptoms in susceptible individuals by increasing intestinal gas production and osmotic load.
- Hormonal influences may explain the higher prevalence in women and symptom fluctuations during menstrual cycles, suggesting a potential role for sex hormones in IBS pathophysiology.
Pathophysiological Mechanisms
- Visceral hypersensitivity and altered gut motility are key pathophysiological features of IBS, contributing to abdominal pain and altered bowel habits 1.
- Intestinal inflammation and dysbiosis of the gut microbiome may also play roles in the development and maintenance of IBS symptoms, with research ongoing into the specific mechanisms involved 1.
- Altered intestinal permeability ("leaky gut") may contribute to immune activation and symptom generation, although more research is needed to fully understand this potential mechanism.
Clinical Implications
- Understanding the complex etiology of IBS helps explain why treatment approaches often need to be multimodal, addressing both physiological and psychological factors to effectively manage symptoms 1.
- A multidisciplinary approach, including medical management, dietary modifications, and psychological therapy, is considered best practice for managing IBS, especially in cases with comorbid mental health disorders.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Irritable Bowel Etiology
The etiology of irritable bowel syndrome (IBS) is complex and multifactorial. Several factors contribute to the development of IBS, including:
- Alterations in gut microbiota 2, 3, 4
- Motility disturbances 2, 3, 4
- Visceral hypersensitivity 3, 4
- Altered CNS processing 3
- Genetic associations 3
- Disturbances in mucosal and immune function 3
- Emotional stress and eating habits 5, 4
- Acute enteric infection 3
- Psychological comorbidity 3
Pathophysiology
The pathophysiology of IBS is not yet completely understood, but it is well established that there is disordered communication between the gut and the brain, leading to motility disturbances, visceral hypersensitivity, and altered CNS processing 3. Other mechanisms that may contribute to the development of IBS include:
- Abnormal gut water secretion 4
- Abnormal gas accumulation 4
- Imbalanced gut microbiota 4
- Certain food constituents that may exacerbate bowel symptoms 4
- The impact of adult and childhood abuses on IBS 4
Diagnosis and Treatment
The diagnosis of IBS is made using criteria based on clinical symptoms, such as the Rome criteria 5. Treatment of IBS requires a multidisciplinary approach and may include:
- Non-pharmacological interventions, such as dietary and lifestyle modification 2, 4
- Pharmacological interventions, such as antispasmodics, stool consistency modifiers, and psychiatric drugs 2, 6, 4
- Probiotics and antibiotics 2, 6, 4
- Diet therapy, including exclusion of certain food constituents 4
- Complementary and alternative medicines (CAMs) 4