IBS is often described as a psychosomatic disorder.  A psychosomatic disorder is defined as a condition in which psychological stresses adversely affect physiological (somatic) functioning to the point of distress. It is a condition of dysfunction or structural damage in bodily organs through inappropriate activation of the involuntary nervous system and the glands of internal secretion. Thus, the psychosomatic symptom emerges as a physiological concomitant of an emotional state.1 According to Habib et al, 70.8% of IBS patients have some form of psychosomatic symptom. In their study, the majority of patients with psychosomatic disorders were in the age group 26-35 (51.44%) and female (53.28%).1

IBS is often described as a psychosomatic disorder [Image: Shutterstock].

About 34% patient had two or more psychosomatic illnesses. Headache (62.26%) and insomnia (63.03%) were the commonest followed by chest pain (36.54%). Chest pain (77.68%), headache (62.26%) and insomnia (56.07%) was more common in male whereas palpitation (60.58%) and breathlessness (57.68%) was more common in female.

Furthermore, studies show that 39.1% of patients with IBS have major depression and about 29% have anxiety disorders.1,2

Definition of anxiety

The Diagnostic and Statistical Manual of Mental Disorders 5th Edition (DSM-V) defines anxiety as:3

  • Excessive anxiety and worry (apprehensive expectation), occurring more days than not for at least six months, about a number of events or activities (such as work or school performance).
  • The individual finds it difficult to control the worry.
  • The anxiety and worry are associated with three (or more) of the following six symptoms (with at least some symptoms having been present for more days than not for the past six months): Restlessness, feeling keyed up or on edge
  • Being easily fatigued
  • Difficulty concentrating or mind going blank
  • Irritability
  • Muscle tension
  • Sleep disturbance (difficulty falling or staying asleep, or restless, unsatisfying sleep)
  • The anxiety, worry, or physical symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning
  • The disturbance is not attributable to the physiological effects of a substance (eg a drug of abuse, a medication) or another medical condition (eg hyperthyroidism)
  • The disturbance is not better explained by another medical disorder (eg anxiety or worry about having panic attacks in panic disorder, negative evaluation in social anxiety disorder [social phobia], contamination or other obsessions in obsessive-compulsive disorder, separation from attachment figures in separation anxiety disorder, reminders of traumatic events in posttraumatic stress disorder, gaining weight in anorexia nervosa, physical complaints in somatic symptom disorder, perceived appearance flaws in body dysmorphic disorder, having a serious illness in illness anxiety disorder, or the content of delusional beliefs in schizophrenia or delusional disorder).

* Note: Only one item required in children.

Definition of IBS

The Rome IV criteria define IBS as a functional bowel disorder in which recurrent abdominal pain is associated with defecation or a change in bowel habits. Disordered bowel habits are typically present (eg constipation, diarrhoea or a mix of constipation and diarrhoea), as are symptoms of abdominal bloating/distension. Symptom onset should occur at least six months prior to diagnosis and symptoms should be present during the last three months.4

Recurrent abdominal pain on average at least one day/week in the last three months, associated with two or more of the following criteria:

  • Related to defection
  • Associated with change in the frequency of stool
  • Associated with a change in the form (appearance of stool).

IBS is subtyped according to the predominant symptoms into:

  • Constipation (IBS-C)
  • Diarrhoea (IBS-D)
  • Mixed (IBS-M)
  • Unspecified (IBS-U).

What causes IBS?

The aetiology of IBS is unclear.  Studies have proposed that it might be caused by the disturbance of function along the brain-gut axis. However, to date, no specific biological abnormality has been identified that could explain the symptoms with specific exceptions such as post-infectious IBS.5

Theories about the pathophysiology of IBS include gastrointestinal (GI) dysmotility, visceral hypersensitivity, low-grade inflammation, increased intestinal mucosal permeability, immunological and genetic factors as well as altered intestinal microbiota.5

A biopsychosocial disease model in IBS

In 1977, American internist and psychiatrist, Dr George Engel, formulated the so-called biopsychosocial disease model. He believed that in order to understand and respond adequately to patients’ suffering and to give them a sense of being understood, clinicians must take the biological, psychological, and social dimensions of illness into consideration.9

In 1998, Prof Douglas Drossman, founder and past chairperson of the Rome Committees, published a paper entitled Gastrointestinal Illness and the Biopsychosocial Model. The aim of the paper was to review the evidence supporting the biopsychosocial model in understanding patients with GI disorders. He described IBS as an illness without a disease and concluded that the biopsychosocial model, can play an extremely important role in the management of GI disorders.10

Rome IV (2016) recommends a biopsychosocial approach to improve adherence and optimise treatment and outcomes.

Biological factors

Genetic factors that have been implicated in IBS include serotonin transporter, IL-1017 and other genetic polymorphisms.

Psychological factors

Emotions and behaviour are often dictated by personality traits. The majority of studies supports the idea that IBS patients have higher levels of neuroticism (tendency to experience negative emotions, such as anger, anxiety or depression) compared to the general population, and patients with similar GI complaints.7

A lot of patients with IBS believe that their chronic gut symptoms indicate a serious illness or even cancer. In addition, patients describe IBS not only as symptoms but mainly as it affects daily function, thoughts, feelings and behaviours.7

Social factors

IBS symptoms are sometimes exacerbated by environmental factors such as stress (eg divorce, relationship difficulties, serious illness, financial problems, abuse, trauma). According to Surdea-Blaga et al, the experience of stressful life events can also determine symptom exacerbation among adults with IBS and frequent healthcare seeking.7

Parental attitudes may also be important to the development or clinical expression of IBS. Levy et al indicated that children of patients with IBS had significantly more healthcare visits than those without IBS.6,8

Long-term or chronic stress can lead to long-term anxiety. The latter is the most common comorbid psychiatric disorder in IBS patients. A study found that environmental factors that played a role in the onset of IBS at an early age (15 years) include:6,7

  • 31% of patients lost a loved one as a result of death, divorce or separation
  • 19% had an alcoholic parent
  • 61% reported unsatisfactory relationships with, or between their parents.

Childhood trauma (eg witnessing a murder, death or illness of a parent) has also been associated with an increased vulnerability for multiple somatic symptoms of which IBS. Therefore, noted Surdea-Blaga et al, childhood deprivation may have an important influence on the etiology of IBS.7

The role of physical and sexual abuse in IBS is unclear, but evidence has shown that is does lead to increased psychological distress. Most probably, as a consequence, abuse is associated with greater impairment of functioning in daily lives, more visits to the doctor and a poorer health outcome.7

The severity of abdominal pain was found to be higher in patients exposed to emotional stress. Stress exacerbated abdominal distension in up to 33% of IBS patients. In addition, data showed that environmental factors and psychosocial stressors (for example history of being psychologically abused, less than six hours of sleep and irregular diet) influenced the progression from an IBS non-consulter to an IBS patient.7

Management approach


Obtaining a detailed history with a few additional questions is warranted to confirm the suspected diagnosis of IBS. It is important to start by ruling out any warning signs. These include:13

o   Age over 50 without prior colon cancer screening; the presence of overt GI bleeding

o   Nocturnal passage of stools

o   Unintentional weight loss

o   A family history

o   Recent changes in bowel habits

o   Presence of a palpable abdominal mass or lymphadenopathy.

If these warning signs are absent, further history should be obtained to quantify the frequency of symptoms and determine whether the patient meets the Rome IV diagnostic criteria.

More specifically, the patient should be asked if his/her pain is present at least one day a week on average for the last three months. The rationale behind the latter two questions is to ensure that the symptoms are recent, and that there is no organic disease manifesting itself over at least six months.

The final component to applying the criteria involves associating the abdominal pain to bowel habits. A careful history should be obtained to confirm whether abdominal pain is related to defecation, a change in stool frequency, or a change in the appearance of stool. In order to clarify the latter characteristic, the Bristol stool chart should be employed as previously described.

A benign physical examination further supports the diagnosis of IBS, although the importance of a physical examination cannot be underestimated as this does reassure the patient.


Because of the interaction between physiological and psychological factors, the management of IBS is complex. Most guidelines recommend pharmacotherapy and non-pharmacotherapy interventions.  The latter include psychotherapy (eg cognitive behavioural therapy) and lifestyle interventions (dietary and complementary and alternative interventions).

Pharmacotherapy for IBS

There is no cure for IBS. As a symptom-based disorder, treatment goals are aimed at resolving symptoms such as pain, bloating, cramping, and diarrhoea or constipation.

The 2019 American Gastroenterological Association (AGA) recommends the following agents, which have been shown to be effective in the management of specific symptoms:11

  • Alosetron hydrochloride is a serotonin 5 HT3 antagonist (blocker) indicated for treatment of women with severe diarrhoea-predominant IBS (IBS-D)
  • Lubiprostone is a chloride channel activator indicated for treatment of IBS with constipation (IBS-C) in women 18 years or older
  • Treatment of specific symptoms:
    • Laxatives (anti-constipation medications), such as milk of magnesia, lactulose, miraLax and linaclotide, are used to treat constipation
    • Anti-diarrheal agents, such as loperamide, diphenoxylate and atropine are used to treat diarrhoea
    • Antispasmodics, such as belladonna alkaloids/ phenobarbital, hyoscyamine, dicyclomine, propantheline and peppermint oil, are used to treat abdominal cramps and associated diarrhoea
    • Antidepressants, such as fluoxetine, citalopram, sertraline, desipramine, amitriptyline, venlafaxine and duloxetine are used to relieve gut pain and treat psychological distress (anxiety and depression). Other types of psychiatric medications can help in unmanageable cases
    • Probiotics, dietary supplements that contain certain beneficial bacteria, may help to balance the intestinal track. More research is needed in this area
    • Antibiotics, such as rifaximin, are used to treat small bowel bacterial overgrowth, which may occur concurrently with or contribute to IBS
    • Fibre supplements can ease the movement of bowel contents, preventing constipation.
Pharmacotherapy for IBS and anxiety

Combination therapy of anti-anxiety and smooth muscle relaxants may be useful. If patients’ symptoms are leading to limiting activities of daily living, low dose tricyclics (eg amitriptyline at doses from 10mg-25mg at night) may be considered.  If the patient experiences significant anxiety or underlying mood disorders, selective serotonin reuptake inhibitors (SSRIs) (eg escitalopram 10mg-20mg) may also be needed, according to Barrow.12

Ford et al evaluated the efficacy of antidepressants and control therapy or usual management in patients with IBS. They found that the relative risk of IBS symptoms not improving with antidepressants versus placebo was 0.66, with similar treatment effects for both tricyclic antidepressants and SSRIs. They concluded that antidepressants are efficacious in reducing symptoms in IBS patients.14


The efficacy of a number of psychotherapy (eg cognitive behavioural therapy, dynamic psychotherapy, hypnotherapy. biofeedback, and relaxation therapy) has been investigated in patients with IBS.13

Psychotherapeutic interventions should be reserved for severe forms of IBS that show high incidence of a comorbid psychological disorder or if a known comorbidity with a depressive or anxiety disorder exists, according to guidelines of the National Institute for Health and Care Excellence, British Society of Gastroenterology and the AGA.13 

A 2005 meta-analysis showed that there is a 25% chance that a patient will benefit from any type of psychotherapy, while hypnotherapy and stress management had a higher rate of success with 52% and 67%, respectively.

More recently, Ford et al found that the RR of symptoms not improving with psychological therapies was 0.69. CBT, relaxation therapy, multi-component psychological therapy, hypnotherapy, and dynamic psychotherapy were all beneficial when data from two or more RCTs were pooled. They concluded that psychological therapies appear to be effective treatments for IBS, although there are limitations in the quality of the evidence, and treatment effects may be overestimated as a result.14

Lifestyle interventions

Lifestyle and diet interventions sometimes are considered before pharmacological treatment. Lack of exercise, food deficiencies, lack or excess of dietary fibre intake, and lack of suitable times for defecation could contribute to the development of IBS, specifically constipation-predominant IBS. An increase in dietary fibres and regular exercise might benefit constipated IBS patients.13

Excessive caffeine consumption, indigestible carbohydrates and high lactose intake have been found to contribute to diarrhoea-predominant IBS. A stepwise food exclusion approach might be effective if the symptoms are mild to moderate.

A meta-analysis has demonstrated significant benefit of the low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols or FODSMAP diet in improving functional GI symptoms in IBS patients.

Probiotics showed modest improvements for bloating, abdominal pain and bowel movement difficulties. No specific probiotic strain was found to be superior to another.

Complementary and alternative interventions

According to the World Gastroenterology Organisation Global Guidelines for IBS, complementary and alternative therapies (CAM) are increasingly being used by patients with IBS.13

A Cochrane review of herbal medicines for the treatment of IBS identified several well-designed clinical studies that showed improvement of IBS symptoms. One study employing a variety of Chinese herbal medicines, given alone or in a fixed combination, showed significant improvement of various IBS symptoms over a placebo treatment that extended beyond the end of the study.

Other alternative treatments frequently used by patients suffering from IBS are peppermint oil and acupuncture. A Cochrane review found that the effects of acupuncture on IBS symptoms were variable and did not differ significantly from the sham acupuncture treatment or any other interventions. This may be due to inconsistencies in study designs and possible inclusion of patients who were not thoroughly diagnosed with IBS prior to treatment.


IBS is the most common functional GI disorder with worldwide a prevalence rate of about 10%.  IBS is commonly associated with anxiety and depression and in some patients, onset can be traced back to stress or trauma. Diagnosis is complicated as a result of the lack of consistent biological markers, the non-specificity of the cardinal symptoms of abdominal pain or discomfort, as well as the heterogeneity of patients. Rome IV recommends a biopsychological approach to diagnosis. Clinicians involved in the management of IBS patients should consider psychological factors when initiating a management plan. Management includes pharmacotherapy and non-pharmacotherapy interventions.

  • Habid A, Ahmad R and Rehman S. Prevalence of associated psychosomatic symptoms in patients of irritable bowel syndrome. IJAM, 2018.
  • Zamani M, Alizabeth-Tabari and Zamani V. Systematic review with meta‐analysis: the prevalence of anxiety and depression in patients with irritable bowel syndrome. AP&T, 2019. 
  • Cecil R. Reynolds, PhD Randy W. Kamphaus, PhD. Generalised Anxiety Disorder. https://images.pearsonclinical.com/images/assets/basc-3/basc3resources/DSM5_DiagnosticCriteria_GeneralizedAnxietyDisorder.pdf
  • Lacy BE and Patel NK. Rome Criteria and a diagnostic approach to irritable bowel syndrome. J Clin Med, 2017.
  • Faresjö Å, Walter S, Norlin A et al.Gastrointestinal symptoms – an illness burden that affects daily work in patients with IBS. Health Qual Life Outcomes, 2019.
  • Tanaka Y, Kanazawa M, Fukudo S and Drossmann DA. Biopsychosocial model of irritable bowel syndrome. J Neurogastroenterol Motil, 2011.
  • Surdea-Blaga, Baban A ad Dumitrascu DL. Psychosocial determinants of irritable bowel syndrome. World J Gastroenterol, 2012.
  • Levy RL and van Tilburg MAL. Functional abdominal pain in childhood: Background studies and recent research trends. Pain Res Manag, 2012.
  • Borrell-Carrio F, Suchman AL and Epstein RM. The Biopsychosocial Model 25 Years Later: Principles, Practice, and Scientific Inquiry. Ann Fam Med, 2004.
  • Drossman DA. Gastrointestinal Illness and the Biopsychosocial Model. Psychosomatic Medicine, 1998.
  • Colombel J-F, Shin A and Gibson PR. AGA Clinical Practice Update on Functional Gastrointestinal Symptoms in Patients with Inflammatory Bowel Disease: Clinical Gastroenterology and Hepatology, 2019. 
  • Barrow P. Stress management in the IBS patient. The Specialist Forum, 2019 (April).
  • Zhou S et al. Pharmacological and non-pharmacological treatments for irritable bowel syndrome. Protocol for a systematic review and network meta-analysis. Medicine, 2019.
  • Ford A, Lacy B, Harris L et al. Effect of Antidepressants and Psychological Therapies in Irritable Bowel Syndrome: An Updated Systematic Review and Meta-Analysis. The American Journal of Gastroenterology, 2019.