What causes Irritable Bowel Syndrome?

We now realise that IBS does not have a single cause but results from a combination of factors that probably vary from person to person. In the past psychological factors were thought to be most important but we now know that this is not the case. Stress and anxiety make the problem worse but that is the case in any illness.

IBS runs in families so it seems reasonable to assume that some people are predisposed to the problem rather like some individuals are predisposed to asthma or migraine. Therefore if you are not predisposed you will probably never get the condition even if you are exposed to a trigger. Triggers include infections - especially of the gut such as gastroenteritis, excessive use of antibiotics, dietary factors, certain drugs such as anti-inflammatories and stress (but this should not be over-rated). It appears that under the right circumstances the gut becomes more sensitive and tends to go into spasm.

Non colonic Symptoms
In addition to abdominal pain, bloating and bowel disturbances, patients with IBS suffer from a variety of other symptoms including:-

  • Nausea
  • Low back pain
  • Lethargy
  • Bladder symptoms - frequency and urgency
  • Gynaecological symptoms - especially pain on intercourse
  • Thigh pain
  • Weight gain
  • Poor skin and hair quality
These are important to recognise because they not only make patients feel even more unwell but they can also lead to the individual being referred to the wrong specialist such as the gynaecologist or back specialist. These features can be very hard to treat but it is helpful if the patient understands that they are part of their IBS and hopefully will improve somewhat if the IBS can be improved.

Functional dyspepsia
This is the name given to a disorder similar to IBS which affects the top end of the gut. The main symptoms are tummy pain affecting the upper abdomen associated with bloating, nausea or feeling easily full up after meals. Patients with functional dyspepsia frequently also suffer from symptoms of IBS so they may, for instance, have an irregular bowel habit. Treatment is not that different to the treatment of IBS with antidepressants often proving quite helpful. We have also shown that hypnotherapy is helpful with this condition (103).

Non cardiac chest pain
This is a functional gastrointestinal disorder that can lead to chest pain that can be very similar to angina. Angina is the name given to pain coming from the heart which is due to narrowing of the coronary arteries (the main arteries to the heart). However, in non cardiac chest pain (NCCP) the pain is coming from the oesophagus (gullet, swallowing tube) and NOT the heart and so patients never die from NCCP. It is extremely important that a heart cause for the pain is excluded first but once that has been done reassurance is very important. However, it is often very hard to reassure patients with NCCP as when they get the pain in their chest they find it hard to believe that it is not coming from the heart. That is why it is so important to make sure that the heart is normal so that the doctor can be absolutely certain that when he is reassuring the patient that heart disease has not been missed.

The actual reason why the oesophagus becomes painful is not entirely clear but it is thought that it is most commonly due to acid. Once an acid cause has been ruled out it seems that the pain is either due to the oesophagus going into spasm or becoming over sensitive. It is usual for doctors to first treat NCCP with anti acid therapy. This usually takes the form of a drug called a histamine 2 (H2) blocker or a proton pump inhibitor (PPI). The PPI's are stronger and usually more effective and the H2 blockers are reserved for people who can't tolerate PPIs. The most common H2 blocker is ranitidine (Zantac) and there are a whole variety of PPI's such as omeprazole (Losec), lansoprazole (Zoton), pantoprazole (Protium) and esomeprazole (Nexium).

If a PPI does not help the pain of NCCP other medications that can help reduce spasm or sensitivity are tried. Occasionally drugs that help angina such as glyceryltrinitate or calcium channel blockers (for example Nifedipane), can also help NCCP chest pain. Unfortunately, they may cause side effects such as headaches that limit their use. Another group of drugs that are often more useful are the antidepressants which are so useful in the other functional gastrointestinal disorders. Benzodiazepines (such as Diazepam) can also be helpful in relieving an episode of chest pain but unfortunately this class of drug has got a bad name because of their potential to cause dependency. This is a real problem but if the patient can be trusted to take them on an "as necessary" basis rather than continuously they can be extremely helpful. The good thing about drugs like diazepam is, other than the risk of dependency and some drowsiness, they are extremely safe.

We have recently shown that hypnotherapy can be very helpful in patients with NCCP (152) and that the beneficial effects are long lasting (159).