What causes IBS?

What causes IBS?

While the consumption of certain foods, food allergies and stressful situations are known to trigger irritable bowel syndrome (IBS), the root cause of IBS is still unknown. 

The following issues that result in flare-ups of IBS have been identified, however, triggers often vary depending on the person:

Gastrointestinal motor issues and IBS

As the colon is compromised for some reason, either due to an infection or type of medication, digestion may slow down causing constipation or increase causing diarrhoea.

Mental health issues and IBS

Stress often aggravates certain physical issues - IBS being one of them. Depression and panic attacks also seem to be linked to IBS. It is still unknown as to whether mental health issues have a direct link to physical ailments or just exacerbate them. 

Brain to gut signal issues

The messages relayed to the intestines from the brain can sometimes not be received correctly, this causes the intestines to not work properly when digesting food.


It is also a plausible theory that IBS is genetic and can run in families. This can be due to genetics or similarly experienced environmental factors – the evidence surrounding these theories is still unclear though.


Cramping and bloating due to IBS may be extremely painful for someone with a low pain threshold. Therefore, someone who does not handle pain very well may experience IBS symptoms more frequently than others who might not recognise them as much.

Bacterial gastroenteritis

A bacterial infection of the intestines (i.e. bacterial gastroenteritis), this can cause IBS symptoms.

Bacterial changes in the small intestine

If the bacteria vital for the digestive processes in the small intestine changes, this has known to result in symptoms of gas (flatulence) as well as diarrhoea.


Women are known to have more severe IBS symptoms when they are having their periods. This had led some doctors to believe that there may be a link between the hormones responsible for reproduction and bowel issues. This is evidence-supported as women tend to experience fewer symptoms of IBS when they have gone through menopause.

Food sensitivity

Certain foods are some of the most well-known triggers for IBS. People often find that after eating a specific food, the symptoms of IBS tend to flare up again.  

Problem foods can include:

  • Alcohol
  • Coffee
  • Dairy
  • Fatty foods
  • Carbohydrates
  • Spicy foods

The theory is that the intestines struggle to absorb specific components of the above foods. This results in bloating, abdominal pain, diarrhoea, constipation and more.

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