What Is IBS?Symptoms, Triggers and How It's Diagnosed

Some weeks your stomach is calm. Then comes the stretch where everything cramps, swells and runs, or refuses to run. You’ve blamed the salad, the coffee, the meeting. The only constant is that it keeps coming back.

What it looks like

The NHS² describes stomach pain or cramps, usually worse after eating and better after doing a poo, abdominal swelling, diarrhea and constipation. It says symptoms come and go, with days that are better and days that are worse, called flare-ups. The NIDDK³ adds bloating, a feeling of not finishing, and whitish mucus in the stool. The NHS also lists gas, fatigue, nausea, back pain and bladder control problems.

The NIDDK¹ describes three types:

• IBS-C: more than a quarter of stools are hard or lumpy, and less than a quarter loose or watery.
• IBS-D: more than a quarter of stools are loose or watery, and less than a quarter hard or lumpy.
• IBS-M: more than a quarter of stools are both hard or lumpy and loose or watery on abnormal bowel movement days.

If constipation is your pattern, see constipation. For gas and swelling, see gas and bloating through the day.

Why it happens, and why women

Doctors haven’t identified a single cause. The NIDDK³ says IBS involves problems with brain-gut interaction, how your brain and gut work together. Contributing factors listed include stressful early-life experiences, depression and anxiety, bacterial infections or overgrowth in the small intestine, food sensitivities and genes. The NIDDK also lists family history and severe digestive infections as risk factors.

For women, the NIDDK³ says symptoms often increase during periods. Our article on stress and anxiety upsetting the stomach goes deeper into the stress link.

The NHS² lists food and drink triggers: alcohol, caffeine, spicy or fatty foods, stress and antibiotics.

The NIDDK¹ says people with IBS often also have other conditions, such as fibromyalgia, chronic fatigue syndrome, anxiety, depression and acid reflux disease. IBS is chronic, often lasting years, the NIDDK says, but it doesn’t lead to other health problems or damage your digestive tract.

How it’s diagnosed

IBS is diagnosed from a pattern, and by ruling out other conditions. The NIDDK⁴ says you have abdominal pain along with two or more of these: pain related to bowel movements, changes in how often you go, or changes in how your stool looks. The symptoms need to have happened at least once a week in the last 3 months, and to have started at least 6 months ago.

Doctors may use tests to exclude other diagnoses, the NIDDK⁴ says: blood tests for anemia and infection, stool tests, a hydrogen breath test, an endoscopy with biopsy to check for celiac disease, and a colonoscopy for colon cancer or inflammatory bowel disease. Lactose is one cause to check, so see dairy and bloating.

For the visit, the NIDDK⁴ says to describe your symptom pattern and timeline, family history of celiac disease, colon cancer or inflammatory bowel disease, recent infections and stressful life events.

What helps

The NIDDK⁵ says different changes help different people with IBS, and recommends talking with a dietitian. Its list:

• Fiber. It may improve constipation by making stool soft and easier to pass. Soluble fiber, in beans, fruits and oats, is more helpful, and the NIDDK⁵ says to increase it by 2 to 3 grams a day to avoid extra gas and bloating.
• Gluten. Some people with IBS have more symptoms after eating gluten, even without celiac disease, and your doctor may suggest trying without it.
• Low FODMAP diet. It cuts carbohydrates that are hard to digest, including certain fruits, vegetables, dairy, wheat products, honey and sugar alcohols. The NIDDK⁵ suggests trying it for a few weeks, then reintroducing foods gradually.

The play

Try this: a symptom and food diary

For two to four weeks, write each day what you ate and drank, your bowel movements, your pain, and where you are in your cycle.

Note stressful days and any antibiotics.

The NIDDK³ says doctors want your symptom pattern and timeline. A diary gives them both.

When to get checked

Don’t wait if

1. Urgent

   Get urgent care if you have unexplained significant weight loss, rectal bleeding or bloody diarrhea, abdominal lumps or swelling, or shortness of breath, palpitations and skin paler than usual. The NHS² lists these as reasons to be seen quickly.

The NHS² says to see a GP if you think you may have IBS and have had symptoms for over 4 weeks. The NIDDK⁴ lists alarm features that suggest a different condition: anemia, bleeding from the rectum, bloody stools or stools that are black and tarry, and weight loss.

Book an appointment if any of these fit:

• Pain and bowel changes have lasted more than 4 weeks
• You’re not sure which type of IBS fits your pattern
• Your symptoms follow your period or stress
• Diet changes haven’t helped
• You have a family history of celiac disease, colon cancer or inflammatory bowel disease

Your stomach has a pattern. A diagnosis starts with writing it down.