IBS: understanding your symptoms and choosing treatment

How the brain and bowel communicate in IBS

The bowel and brain continually exchange signals. In IBS, normal stretching, food movement or gas may feel more uncomfortable, and bowel movement can be faster or slower than usual. Previous infection, food, sleep and stress can influence this system. This does not mean you imagined the symptoms or need to be anxious to have IBS.

IBS itself does not damage the bowel or turn into cancer. It is different from inflammatory bowel disease (IBD). However, someone with IBS can develop another condition, so a new symptom should not automatically be attributed to their existing diagnosis.

How I make the diagnosis

I look for recurring pain or discomfort associated with passing poo or changes in its frequency or appearance. Some people mainly have constipation (IBS-C), some diarrhoea (IBS-D), and some both (IBS-M). The pattern can change over time and with treatment. Bloating alone does not establish IBS.

IBS is a clinical diagnosis based on the symptom pattern, examination and exclusion of the important alternative diagnoses relevant to you. You do not need every possible investigation before starting treatment; often a limited, targeted set of tests is enough. If symptoms are unusual, change or raise concern, I may recommend further investigation.

Am I too old to have IBS?

IBS can be diagnosed at any age. The diagnosis is based on the symptom pattern, examination and the most relevant tests, rather than age alone.

When symptoms begin later in life, or change in someone who already has IBS, I look carefully for other causes as well. Depending on the symptoms and examination, these may include bowel cancer, inflammatory bowel disease, coeliac disease, microscopic colitis or an effect of medicines.

Warning signs such as bleeding, iron deficiency, weight loss or symptoms that wake you from sleep need assessment rather than being assumed to be IBS.

Which tests are useful?

Blood tests may include a blood count, inflammatory marker and coeliac screen. Keep eating gluten until coeliac testing and any necessary diagnostic assessment are complete, unless your clinical team advises otherwise. If diarrhoea is present, faecal calprotectin can help assess whether bowel inflammation needs further investigation.

FIT measures blood and is not a test for IBS. A normal FIT does not exclude all causes of symptoms or replace a recommended colonoscopy. Bleeding, unexplained iron deficiency, weight loss, a lump or a concerning family history may require a different investigation pathway.

Routine commercial food-IgG or microbiome panels do not establish an IBS diagnosis. I am happy to discuss the evidence available, and the evidence gaps, behind tests you may have heard about.

Meals, movement and a regular bowel routine

Regular meals, manageable portion sizes, physical activity and a consistent sleep routine are useful starting points. A brief record of stool form, pain, meals and treatments can show what is changing. There is no need to track every mouthful indefinitely.

If you have constipation, improving stool consistency may help discomfort, but persistent pain may need additional treatment. With diarrhoea, review caffeine, alcohol and sugar-free products as possible triggers. Change one or two things at a time so we can judge whether they helped.

Choosing the type and amount of fibre

Soluble fibre such as psyllium can help IBS symptoms and bowel consistency. Start with a small amount and increase gradually according to tolerance and the product instructions. Take it with adequate fluid. Ask first if you have swallowing problems, a known bowel narrowing or a prescribed fluid restriction.

A large increase in wheat bran can worsen bloating and pain. That does not mean all fruit, vegetables, grains, nuts and seeds should be removed. Foods contain mixtures of fibre, and the amount you tolerate can differ. I would involve a dietitian when adjusting food choices becomes difficult.

Trying a low-FODMAP diet, then adding foods back

FODMAPs are fermentable carbohydrates that can draw water into the bowel and produce gas. Some people with IBS are sensitive to the resulting stretch. If simpler changes have not helped, a dietitian-guided low-FODMAP trial may be useful.

The restrictive phase is short. It is followed by planned reintroduction and a diet based on what you personally tolerate. The aim is to expand your choices, not avoid every high-FODMAP food forever.

If you are losing weight, already eating very little or becoming afraid of food, tell me before trying another exclusion diet. Do not begin a gluten-free diet before coeliac assessment.

Medicines and other treatments for your symptoms

I choose treatment for the symptom that is affecting you most, then review whether it has helped. A medicine that improves stool consistency may not treat pain or bloating. The dose, side effects and your other health conditions guide the choice.

Related information

• Constipation and difficult emptying
• Coeliac testing before changing your diet
• What calprotectin can tell us
• Ongoing symptoms after a negative FIT
• Understanding inflammatory bowel disease (IBD)
• Microscopic colitis: when the camera looks normal