Irritable bowel syndrome (IBS): symptoms, treatment and diet

The NHS lists four main symptoms: stomach pain or cramps, usually worse after eating and better after doing a poo; bloating, where your tummy feels uncomfortably full and swollen; diarrhoea, with watery poo and sometimes sudden urges; and constipation, where you strain and feel you cannot empty your bowels fully.

There may be days when symptoms are better and days when they are worse (flare-ups). Guts UK says symptoms can occur daily or come and go over weeks or months, and may change over time.

IBS can also cause wind, passing mucus in poo, tiredness, feeling sick, backache, bladder problems such as needing to pee often or urgently, not always being able to control when you poo, and pelvic pain.

Guts UK says IBS is often described by the main bowel pattern. About 1 in 3 people have IBS with constipation (IBS-C) and about another third have IBS with diarrhoea (IBS-D). Others do not fall into a specific pattern, or have both constipation and diarrhoea (IBS-M).

IBS is a long-term condition of the digestive system. NHS inform says the exact cause is unknown and that many suggested causes have not been proven to lead to IBS.

Guts UK describes it as a disorder of the way the gut and brain communicate, in which nerves in the gut can be too sensitive to normal movement of the bowel, causing pain. It says a gut infection or antibiotic use can start the condition for some people, that IBS tends to run in families although no gene has been found, and that changes in gut microbes and endometriosis have been linked to it.

The NHS says a GP will ask what symptoms you have, whether they come and go, how often and when you get them, and how long you have had them. They may feel your tummy for lumps or swelling.

There is no test for IBS. The NHS says you might need a blood test to check for problems such as coeliac disease and tests on a poo sample to check for infections and inflammatory bowel disease. You will not usually need further hospital tests unless the GP is not sure what the problem is.

NHS inform advises not changing your diet until these tests are done, because the coeliac blood test can be affected by what you eat. Guts UK says doctors use guidelines in which pain happens on average one day a week or more for at least three months and is linked to a change in bowel habit.

The NHS says there is no single diet or medicine that works for everyone with IBS. It suggests eating a healthy, balanced diet, keeping a diary of what you eat and any symptoms, and drinking at least 8 to 10 drinks (around 1.5 litres) of fluid a day.

It advises not skipping or delaying meals, not eating too quickly, and not eating lots of fatty, spicy or processed foods. It also suggests no more than 3 portions of fresh fruit a day (a portion is 80g) and no more than 3 cups of tea, coffee or other caffeinated drinks a day.

• For bloating, cramps and wind: eat oats regularly, have up to 1 tablespoon of linseeds a day, and avoid hard-to-digest foods such as cabbage, broccoli, cauliflower, brussels sprouts, beans and onions.

• For diarrhoea: cut down on high-fibre foods such as wholegrain foods, nuts and seeds, and avoid products containing the sweetener sorbitol.

• For constipation: drink plenty of water and increase soluble fibre such as oats, pulses, carrots, peeled potatoes and linseeds.

• Probiotics: the NHS says you can try them for a month, and Guts UK says trying them for up to 12 weeks is recommended, stopping if there is no improvement.

Guts UK says that if simple dietary advice does not help, a state-registered dietitian can look for trigger foods by removing certain foods and adding them back slowly. One form of this is the low FODMAP diet, which excludes short-chain fermentable carbohydrates, and it says it works for about half to two thirds of people with IBS.

Guts UK recommends not trying exclusion diets on your own and advises that they may not be suitable if you have, or have had, an eating disorder. It also says there is little evidence that a gluten-free diet helps IBS symptoms.

Guts UK says lifestyle changes such as diet and exercise should be the first approach, with medicines tried if those are not effective, and that because IBS is individual, if one medicine does not help another could be tried.

The NHS suggests asking a pharmacist about medicines such as Buscopan or peppermint oil for cramps, loperamide (Imodium) for diarrhoea and laxatives such as Fybogel for constipation. Guts UK adds that antispasmodics such as mebeverine and alverine can be used for pain and wind, and that guidelines recommend avoiding lactulose as it may worsen wind.

If simple measures have not helped, Guts UK says a GP may consider a low dose of amitriptyline, which works on gut-brain signalling and is used at lower doses than for depression. If symptoms continue for 12 months, gut-directed hypnotherapy or IBS-specific cognitive behavioural therapy can be considered. The NHS says to see a GP if diet changes and pharmacy medicines are not helping.

The sources used here describe IBS mainly in adults. Guts UK says doctors can diagnose IBS at any stage of life, with the most common age being 20 to 40. A child with persistent tummy pain, poor growth or blood in the poo needs to be seen by a GP rather than assumed to have IBS.

If you are pregnant and have IBS, check with your midwife, GP or pharmacist before using any medicine, including pharmacy treatments, as not all of those mentioned above will be suitable.

See a GP if you think you might have IBS and have had symptoms for over 4 weeks, so they can check and rule out other problems.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have lost a lot of weight for no reason, are bleeding from your bottom or have bloody diarrhoea, find a hard lump or swelling in your tummy, or have shortness of breath, noticeable heartbeats and skin that is paler than usual. NHS inform adds that a change in bowel habit lasting more than 6 weeks, especially over the age of 50, needs prompt attention.

On the NHS, IBS is usually diagnosed and managed in general practice, with referral to a dietitian or gastroenterologist if symptoms do not respond. Guts UK notes that gut-directed psychological therapies can have long waiting times.

Private dietitians, gastroenterologists and therapists are also available. Whichever route you choose, make sure coeliac disease and inflammatory bowel disease have been considered before changing your diet, and check that any practitioner advising an exclusion diet is a registered dietitian.