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Health guide

Functional Medicine for IBS

Review approval confirmed 5 October 2026

What is Irritable Bowel Disease?

The condition discussed here is irritable bowel syndrome (IBS), not inflammatory bowel disease (IBD). IBS affects bowel function and can be diagnosed from a typical symptom pattern alongside appropriate checks for other causes. [1]

IBS can affect quality of life, and symptoms deserve attention whether or not anxiety is also present. Anxiety is not evidence that bowel symptoms are imagined. [1]

Signs and Symptoms of IBS

The signs and symptoms of IBS vary but are usually present for a long time. The symptom severity can also be varied but typical common symptoms include:

  • Constipation
  • Diarrhoea
  • Passing mucus when you pass a stool
  • Bloating
  • Abdominal pain, cramping or stomach pains
  • Feeling nauseous
  • Gas production and passing excessive amounts of wind
  • Tiredness and lack and energy
  • Changes in the appearance of bowel movement
  • Changes in how often you are having a bowel movement
  • These symptoms often come and go and are usually worse after eating and relieved by passing a stool

What Caused IBS?

The precise cause of Irritable Bowel Syndrome isn’t known. Factors that appear to play a role include:

  • Muscle contractions in the intestine. The walls of the intestines are lined with layers of muscle that contract as they move food through your digestive tract. Contractions that are stronger and last longer than normal can cause gas, bloating and diarrhoea. Weak intestinal contractions can slow food passage and lead to hard, dry stools.
  • Nervous system. Abnormalities in the nerves in your digestive system may cause you to experience greater than normal discomfort when your abdomen stretches from gas or stool. Poorly coordinated signals between the brain and the intestines can cause your body to overreact to changes that normally occur in the digestive process, resulting in pain, diarrhoea or constipation.
  • Severe infection. IBS can develop after a severe bout of diarrhoea (gastroenteritis) caused by bacteria or a virus. IBS might also be associated with a surplus of bacteria in the intestines (bacterial overgrowth).
  • Early life stress and stress levels. People exposed to stressful events, especially in childhood, tend to have more symptoms of IBS.
  • Changes in gut microbes. Examples include changes in bacteria overgrowth, fungi and viruses, which normally reside in the intestines and play a key role in health. Research indicates that the microbes in people with IBS might differ from those in healthy people.
  • IBS is not diagnosed by assuming a damaged or “leaky” gut lining. Blood tests and, where indicated, stool tests help assess alternative causes such as coeliac disease or inflammation. Broad commercial microbiome or food-intolerance panels do not establish the cause of IBS. [1]

Triggers

Symptoms of IBS can be triggered by:

  • Some foods can worsen IBS symptoms. Food allergy is a different condition; symptoms after a meal do not by themselves show an allergy or justify removing whole food groups. [1]
  • Stress can affect the gut–brain interaction and worsen symptoms. This does not make IBS an imaginary condition or mean that stress is its only cause. [1]

Risk factors

Many people have occasional signs and symptoms of IBS. But you’re more likely to have the syndrome if you:

  • Are young. IBS occurs more frequently in people under age 50.
  • IBS is reported more often in women in many studies. Sex or hormone use alone does not diagnose IBS. [1]
  • Have a family history of IBS. Genes may play a role, as may share factors in a family’s environment or a combination of genes and environment.
  • Have anxiety, depression or other mental health issues. A history of sexual, physical or emotional abuse also might be a risk factor.

Complications

Chronic constipation or diarrhoea can cause haemorrhoids.

In addition, IBS is associated with:

  • Poor quality of life. Frequent pain and bowel symptoms can affect work, study, relationships and daily activities. The effect differs between people. [1]
  • Mood disorders. Experiencing the signs and symptoms of IBS can lead to depression or anxiety. Depression and anxiety also can make IBS worse.

IBS and Functional Medicine

IBS can persist for years and affect daily life. Meals can trigger symptoms, but a food-related symptom does not by itself identify inflammation or an allergy. Diet and lifestyle measures may help alongside other evidence-based treatment. [1]

A functional medicine consultation may consider diet, activity, sleep and stress alongside standard IBS care. It should not be presented as superior to conventional treatment or as a guaranteed way to eliminate symptoms. Low-FODMAP advice should be given by a suitably trained professional; response to probiotics varies. [1]

Assessment should begin with the symptom history, medicines, examination and appropriate tests. Low stomach acid, neurotransmitter imbalance or a damaged microbiome should not be assumed to explain IBS without reliable evidence. [1]

The aim is to reduce symptoms and improve daily life through a plan that is reviewed over time. Complete symptom resolution cannot be guaranteed. [1]

Fatigue, poor sleep or other symptoms may coexist with IBS. New or persistent symptoms need assessment in their own right rather than being attributed automatically to the gut. [1]

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