A Guide to Irritable Bowel Syndrome (IBS)

Medically Reviewed By Kelsey Trull, PA-C

Irritable bowel syndrome (IBS) causes digestive and bowel symptoms that include stomach pain, constipation and diarrhea, and bloating. The condition can occur without other signs of disease or damage to the digestive tract. IBS affects the stomach and intestines, also referred to as the digestive tract, or part of the gastrointestinal system.

IBS is a common condition that can be long term or lifelong, but treatment can improve symptoms and your quality of life.

This article discusses IBS, including its symptoms, causes, and risk factors. It also explains the diagnosis, treatment, and outlook.

What are the symptoms and types of IBS?

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There are different types of IBS, which may cause various symptoms:

  • IBS with constipation (IBS-C): During IBS flare-ups, IBS-C is when more than a quarter of your stools seem lumpy or hard, and less than a quarter seem watery or loose.
  • IBS with diarrhea (IBS-D): IBS-D is when more than a quarter of your stools seem watery or loose, and less than a quarter seem lumpy or hard.
  • IBS with mixed bowel habits (IBS-M): This is when more than a quarter of your stools seem lumpy or hard, and more than a quarter seem watery or loose.

Read more about the different types of IBS.

Other IBS symptoms include:

  • cramping or pain in the stomach area, which may improve after passing a stool
  • bloating or swelling of the stomach
  • gas
  • lower abdominal pain before a bowel movement, or pain when passing bowel movements
  • a feeling of urgency to pass bowel movements
  • feeling like your bowel movements are incomplete
  • mucus in the stool
  • lack of energy
  • nausea
  • discomfort or nausea after eating an appropriate-size meal
  • other changes in bowel movements, such as any changes in consistency or frequency
  • symptoms that may flare up during menstrual periods

Contact your doctor if you have symptoms of IBS.

What causes irritable bowel syndrome?

The cause of IBS is unknown, but there are several theories. The National Institutes of Health (NIH) suggests a combination of factors may be responsible.

Some theories suggested by the NIH and other research include:

  • Immune responses: Immune responses may contribute Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source to IBS. For example, some people’s intestines may be highly sensitive to stress and bacteria. This may cause an immune response that leads to inflammation and irritation, affecting bowel movements.
  • Bacterial imbalance: Imbalances in gut bacteria may cause IBS. Some bacteria is beneficial for digestion. However, bacterial infection or small intestinal bacterial overgrowth (SIBO) may disrupt the balance of beneficial and nonbeneficial bacteria, causing irritation. IBS that follows an infection is also known as post-infectious IBS.
  • Brain and gut communication: Issues with how the brain and gut work together to coordinate digestion may cause IBS, including:
    • Serotonin is a hormone that helps the brain and gut communicate and function. As suggested by a 2020 review Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , some people with IBS have excess serotonin levels, which may lead to diarrhea and discomfort.
    • The brain helps coordinate muscle movements. With IBS, the digestive tract muscles may push waste along the tract too slowly. As a result, the intestine may absorb too much fluid, leading to dry or hard stools and constipation. Alternatively, the muscles may contract too quickly, meaning the intestines don’t absorb enough fluid, leading to watery stools and diarrhea.

However, more research is needed to confirm how and why IBS develops.

How does diet and nutrition affect IBS?

IBS symptoms can closely relate to the foods you eat. For example, eating very large portions at once may irritate the stomach.

Also, specific triggers can worsen IBS symptoms. Some foods and ingredients clinicians commonly recommend Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source limiting or avoiding include Trusted Source Office on Women's Health Governmental authority Go to source :

  • alcohol
  • caffeine
  • carbonated drinks
  • artificial sweeteners such as sorbitol
  • high-fructose corn syrup
  • spicy foods
  • high levels of fat
  • insoluble fibers, such as whole wheat products, beans, and potatoes
  • dairy, such as milk, cheese, or ice cream

Your doctor may also recommend avoiding gluten to see whether your symptoms improve. Some people with IBS may experience gluten as a trigger, even if they do not have any other gluten-related conditions, such as celiac disease.

As a result, certain diets and nutritional approaches may help IBS symptoms or reduce flare-ups.

What are the risk factors for irritable bowel syndrome?

Some factors may increase the risk of IBS or increase the risk of worsened symptoms. These factors include:

  • having been assigned female at birth
  • hormonal changes, such as Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source menstrual periods
  • family history of IBS
  • stress
  • a history of stressful or difficult events in childhood
  • previous gastrointestinal infection
  • anxiety, depression, or other psychological conditions
  • diet, such as inflammatory diets or diets higher in:
    • overall calories
    • total fats and saturated fats
    • carbohydrates

How do doctors diagnose irritable bowel syndrome?

There is no one test for IBS. Instead, a doctor will ask questions about your symptoms and medical history. If your symptoms meet certain criteria, your doctor may suspect IBS.

For example, doctors may diagnose IBS if you have experienced abdominal pain at least 1 day a week for the past 3 months, as well as at least 2 of the following features:

  • pain that links to bowel movements
  • changes in the frequency of bowel movements
  • changes in the appearance of the stool

Your doctor may conduct a physical exam, such as by feeling your stomach or checking your blood pressure.

Doctors can also order tests to ensure your symptoms are not due to a different condition. Tests include:

  • blood tests
  • stool samples, to check for blood or evidence of infection
  • sigmoidoscopy, in which a flexible, lighted tube with a tiny camera is inserted into the rectum
  • colonoscopy, in which a longer tube examines the entire colon
  • barium X-ray, in which you ingest a solution that helps show abnormalities on X-ray images

You may be asked to stop eating or drinking certain foods for a few weeks to determine whether your symptoms may result from food intolerance. For example, your doctor may ask you to eliminate dairy products if they suspect lactose intolerance.

How is irritable bowel syndrome treated?

Treatment can help ease symptoms, address nutritional imbalances, and reduce flare-ups.

The following are treatment options for IBS.

Dietary approaches for IBS

Doctors may recommend specific diets or learning and avoiding your IBS triggers to help ease symptoms.

For example, dietary approaches IBS include:

Learn more about a FODMAP diet for IBS and adding fiber to the diet.

Medications for IBS

Depending on your condition and symptoms, your doctor may recommend medications, such as:

  • probiotics, which can be available over the counter (OTC)
  • medications to stop diarrhea, such as:
    • loperamide (Imodium, Diamode)
    • rifaximin (Xifaxan)
    • eluxadoline (Viberzi, Truberzi)
    • alosetron (Lotronex)
  • medications to help with constipation, such as:
    • laxatives
    • lubiprostone (Amitiza)
    • plecanatide (Trulance)
    • linaclotide (Linzess)
    • fiber supplements

Ask your doctor or a pharmacist for recommendations before using probiotics.

Other medications that can help alleviate abdominal pain include:

  • antispasmodic medications
  • certain antidepressants, including selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants
  • peppermint oil capsules

Other approaches

As well as prescription treatment, the following self-care methods may also help you manage or alleviate your symptoms:

Your healthcare team may also recommend complementary techniques that work alongside traditional medical approaches. Though they may not cure IBS or replace medical treatments, they may help improve symptoms or quality of life.

Examples include:

Always ask for medical advice before trying new supplements or remedies, even if they are available OTC, to avoid interactions with medications, substances, or underlying health conditions.

What is the outlook of irritable bowel syndrome?

IBS can be long term, or symptoms may go away and come back with time. IBS complications include:

However, treatment can help reduce IBS symptoms significantly or make them more manageable.

Is IBS curable?

Currently, IBS has no known cure Trusted Source Office on Women's Health Governmental authority Go to source , but treatment can reduce symptoms and flare-ups.

Also, some people have experienced improvement over time — sometimes even no longer experiencing symptoms. Research Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source cites examples of people who experience Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source post-infectious IBS and those who had IBS as children.

Talk with your doctor if you have questions about your treatment or outlook.


IBS is a combination of digestive symptoms that can include diarrhea, constipation, abdominal pain, and bloating.

The cause of the condition is unknown, but theories include colon sensitivity and an imbalance of bacteria in the digestive tract.

IBS has no known cure but treatments include medication, probiotics, and dietary approaches.

Contact your doctor if you have symptoms of IBS.

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Medical Reviewer: Kelsey Trull, PA-C
Last Review Date: 2023 Jul 26
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