Irritable bowel syndrome - Medical information

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most common intestinal upset, affecting 1-2 in every 10 people. IBS is not dangerous in any way, but it can be uncomfortable, unpleasant, and distressing.

IBS symptoms vary from one person to another. Symptoms can include vague abdominal discomfort, a sense of fullness sometimes called bloating, spasm-like pain in the tummy that comes in waves, constipation in some, and loose motions or diarrhoea in others.

There can be other symptoms as well including mucous (slime) from the back passage (but not blood), feeling sick, backache, tiredness, and urinary symptoms.

Irritable bowel syndrome symptoms are intermittent. They come and go.

Symptoms may be present for a few days at a time, or a week, or longer. They usually settle down completely between flare-ups only to come back later. In some people Irritable bowel syndrome is triggered in by stress. Some people can identify particular foods associated with a flare-up of their symptoms.

IBS symptoms may be anything from occasional and mild through to severe distressing and incapacitating. The pain can be severe and very real.

Causes of IBS

There is no single known cause for IBS. People with IBS seem to have developed more sensitive nerves in their bowel. There may also be links with too fast or too slow passage of food through the bowel, gut microbes, the immune system, stress, and a genetic effect as often other family members also suffer with IBS.

Caution with self-diagnosis and treatment

IBS has certain recognisable features that help to confirm the diagnosis:

  • People usually have IBS on and off for many years, and a diagnosis should only be made after at least 6 months of symptoms.
  • IBS usually starts in your 20-30s.
  • The pattern of symptoms of IBS are usually similar from one flare-up to the next.
  • People with IBS are usually perfectly well and symptom free between flare-ups.

Symptoms to report to your GP

Where self-treatment is not recommended:

  • Weight loss (people with IBS usually do not lose weight).
  • Constant pain or increasing pain in one spot (the pain of IBS usually comes and goes during a flare up and disappears completely between flare ups).
  • Worsening constipation suggesting a blockage of the bowel.
  • New symptoms of blood in the motions (stools). IBS can cause diarrhoea but not blood in the stool.
  • Symptoms starting in people over 40 (IBS usually starts early in life although it may be a life-long complaint).
  • Women with new symptoms of IBS especially bloating, feeling full, loss of appetite, abdominal pain, urinary symptoms (early symptoms of ovarian cancer can be confused with IBS).
  • Nausea or loss of appetite.
  • Pale and tired.
  • Running a high temperature (fever).
  • Recent travel abroad (possible tropical bowel disease).
  • IBS symptoms in pregnancy.

If in doubt please see a GP and do not self-treat.

Treatment available

We supplies a range of medicines which reduce bowel spasm, bloating, pain, and diarrhoea associated with IBS. Details are listed below, and a table comparing treatments is available in the FAQs - Which is the best IBS medication?

Significant side effects from IBS medications are rare.


Contains hyoscine butylbromide which relieves gut spasms.

  • Buscopan 10mg: take 1-2 tablets 3-4 times a day.


Contains mebeverine, an antispasmodic.

  • Colofac 135mg (sugar-coated): take 1 capsule 3 times daily before meals.
  • Colofac MR 200mg (slow release): take 1 capsule twice daily.
  • Possible side effects: can very rarely trigger an allergic reaction.

Fybogel Mebeverine

Contains mebeverine (antispasmodic) plus soluble fibre (isphagula husk) which helps with constipation. For some people this works better than Colofac on its own.

  • Fybogel Mebeverine 135mg + ispaghula husk 3.5g (orange-flavour): take 1 sachet 2-3 times daily with plenty of water to prevent the fibre bulking too much and causing a bowel blockage.
  • Possible side effects: can very rarely trigger an allergic reaction. Contains aspartame.


Contains the natural soothing ingredient peppermint oil. Also contains peanut oil.

  • Colpermin (peppermint oil 0.2mls): take 1-2 capsules 3 times daily.
  • Possible side effects: can cause heartburn, soreness around the anus, and mouth soreness if the tablets are chewed (should be swallowed whole).


Contains contains alverine, an antispasmodic. Lower cost generic version also available.

  • Spasmonal (alverine 60mg): take 1-2 capsules 3 times daily before meals.
  • Spasmonal Forte (alverine 120mg): take 1 capsule 3 times daily before meals.
  • Possible side effects: can very rarely trigger an allergic reaction; linked to liver inflammation and altered liver tests on rare occasions.


Works to slow bowel spasms and reduce diarrhoea.

  • Loperamide 2mg: take 1 capsule up to 6 times per day after episodes of diarrhoea.
  • Possible side effects: taking too much loperamide can lead to constipation.

What else can I try?

Other things that help in some people but not others are: eating more fibre, eating less fibre, avoiding foods that seem to be associated with a flare-up, trying to reduce stress, drinking plenty (minimum of 1.5L/day), regular exercise, and possibly for some people probiotics.