Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder that causes symptoms such as abdominal pain, bloating and changes in bowel habits. Symptoms can range from mild to severe, come and go, or change in intensity over time.
There are three main types of IBS, classified based on whether a person has diarrhea, constipation, or both.
Identifying the type of IBS you have ensures that your treatment plan effectively manages your symptoms and improves your quality of life.
IBS with diarrhea (IBS-D) is the most common form of irritable bowel syndrome, affecting about 40% of people with IBS. It is associated with frequent episodes of diarrhea.
The exact cause of IBS-D is unknown, although research suggests that changes in the gut microbiota—the trillions of bacteria, fungi, and other microbes that live in the gut and help digest the food you eat—play a role.
Dysbiosisan imbalance of gut microbiota can alter the gut-brain axis. The gut-brain axis is a signaling network between the gut microbiota and the brain. With IBS-D, disturbances in the gut-brain axis can cause food to move too quickly through the intestines, leading to diarrhea, abdominal cramps, and other symptoms.
Dysbiosis can also make the nerves in the gut more sensitive and hyper-reactive to normal digestive activities, so even the normal movement of food or gas through the gut can cause pain and discomfort in people with IBS-D.
Symptoms
IBS-D is associated with frequent diarrhea. On days when symptoms are active, at least 25% of stools will be loose or watery, while less than 25% will be hard or lumpy. Other common symptoms of IBS-D include:
- A sudden, urgent need to have a bowel movement
- Abdominal cramps, which are usually relieved after a bowel movement
- Bloating and gas
- Bowel incontinence
- Whitish mucus in the stool
These symptoms can have a significant impact on your daily life, leading to fatigue, anxiety and depression. People with IBS-D report that their symptoms affect their work productivity and ability to engage in daily activities and hobbies.
IBS with constipation (IBS-C) is associated with infrequent, hard stools. IBS-C is more common in people who were assigned female at birth. It often develops in adolescents and young adults, but it can affect people of all ages.
Although the cause of IBS-C is not fully understood, several factors likely contribute to its development. Dysbiosis (changes in gut microbiota) may also be a major factor in IBS-C.
Dysbiosis with IBS-C can cause slower digestion, meaning that food and waste move through the intestines more slowly than usual. This delayed movement allows the colon to absorb more water from the stool (poop), making the stool hard, dry and difficult to pass.
A low-fiber diet can also contribute to IBS-C. Fiber helps bulk up the stool and encourages the movement of waste through the intestines. People with IBS-C often have increased sensitivities to certain foods, such as dairy, gluten, and high-fat foods. Even small amounts of these foods can irritate the digestive system, causing or worsening constipation in people with IBS-C.
Symptoms
IBS-C causes frequent constipation, which is difficult or infrequent bowel movements. On days when symptoms are active, more than 25% of stools are hard or lumpy, while less than 25% are loose or watery. Other common symptoms of IBS-C include:
- Persistent abdominal pain or cramps
- Severe bloating and gas
- Straining while trying to have a bowel movement
- Infrequent bowel movements, sometimes less than three times a week
- Tenesmus, a feeling of incomplete emptying of the bowels
While IBS-C symptoms may improve temporarily after having a bowel movement, long-term symptom relief requires following your treatment plan.
People who have IBS with mixed bowel habits (IBS-M) experience a combination of diarrhea and constipation. This form of IBS can be trickier to manage because symptoms can change unexpectedly. IBS-M affects both men and women equally.
Although the cause of IBS-M is not fully understood, research suggests that an imbalance in the gut microbiome may lead to problems with the gut-brain axis.
Problems with the gut-brain axis can lead to an imbalance of gut motility, where the intestines alternately move food too quickly (causing diarrhea) and too slowly (causing constipation). This irregular movement interferes with digestion and makes the stool constantly unpredictable.
Factors such as emotional stress and certain foods can cause or worsen symptoms and increase the likelihood of rapid, unpleasant changes in bowel habits.
Symptoms
In IBS-M, symptoms vary between constipation and diarrhea. On the days you experience symptoms, more than 25% of stools are hard or lumpy, and more than 25% are watery and loose. Other common symptoms of IBS-M include:
- Abdominal cramps that vary in intensity and location
- Gas and bloating, which can vary as your stool changes
- An urgent need to empty the bowels from time to time, while sometimes there are difficulties with the stool
- A feeling of incomplete emptying of the bowels
- Mucus in the stool
- A feeling of unpleasant satiety or nausea after a meal
Diagnosing IBS and determining your type involves a thorough medical history and review of symptoms, a physical exam, and diagnostic tests.
Healthcare providers use the Roman criteria to diagnose IBS. The Rome criteria state that to be diagnosed with IBS, you must experience abdominal pain at least once a week for the past three months associated with two or more of the following:
- Bowel movements
- Changes in the appearance (texture) of bowel movements
- Changes in the frequency of bowel movements
Diagnostic tests are not always necessary to diagnose IBS, but your healthcare provider may order tests to rule out other conditions with symptoms similar to IBS. These tests include:
- Chair test: This involves analyzing a stool sample to check for infection, inflammation or the presence of blood. The test can help rule out inflammatory bowel disease (IBD) or bacterial intestinal infections.
- Blood test: A health care professional will take blood from a vein and check for signs of inflammation, infection, or anemia. Specific markers, such as C-reactive protein (CRP) and white blood cell count, indicate inflammation or infection that is not common in IBS.
- Colonoscopy: A healthcare professional inserts a thin, flexible tube with a small camera into the anus to examine the intestinal lining. This test can help rule out conditions such as IBD and colorectal cancer.
- Hydrogen breath test: This measures the amount of hydrogen gas in your breath, which can identify lactose intolerance or small intestinal bacterial overgrowth (SIBO).
- manometry: This specialized test measures the strength and coordination of muscle contractions in the colon. A thin, flexible tube with pressure sensors is placed inside the colon to monitor how well the muscles move food through the colon.
Diagnostic tests cannot diagnose specific types of IBS, so it can be helpful to keep a record of your symptoms to help your doctor determine which type you have. This log should contain details of the following:
- Stool frequency
- Stool consistency
- Pain or discomfort you feel
- Diet, exercise, stress and sleep levels (to identify symptom triggers)
See your doctor if you experience persistent IBS symptoms. While occasional diarrhea and constipation are common, persistent symptoms may be a sign that you have IBS or another digestive disorder.
If your healthcare provider diagnoses you with IBS, they can help identify the specific type and create a treatment plan that can help effectively manage your symptoms.
Common treatments for IBS include dietary changes, stress management techniques, and medications such as anti-diarrhea medications, anticholinergic medications to control intestinal spasms, or laxatives to treat constipation. Probiotics or fiber supplements can also help improve gut microbiota and promote healthy bowel movements.
Certain symptoms are red flags for more serious conditions that require immediate medical attention. Contact your doctor as soon as possible if you experience:
- Bloody stool
- Severe or persistent pain
- Nausea or vomiting
- Fever
- Abdominal pain and/or diarrhea at night
- Unintentional weight loss
It is not always possible to prevent irritable bowel syndrome, but certain changes in lifestyle and eating habits can help reduce symptoms or prevent them from getting worse:
- Eat a balanced diet: A diet with smaller, more frequent meals can help manage IBS symptoms. Including more soluble fiber — found in fruits, beans and oat products — can improve stool consistency and frequency. A low-FODMAP diet may be helpful. It involves avoiding foods high in certain carbohydrates that are more difficult to digest, including dairy products, wheat and rye products, and certain fruits.
- Manage stress: Stress and psychological distress can cause or worsen IBS symptoms. Stress management techniques such as mindfulness meditation and breathing exercises can help reduce stress levels.
- Exercise: Regular physical activity can support digestion and reduce stress levels to manage IBS symptoms.
Irritable bowel syndrome (IBS) causes abdominal pain and changes in bowel habits. Its subtypes are IBS-D (diarrhea), IBS-C (constipation), and IBS-M (both diarrhea and constipation).
Treatment approaches vary depending on the type of IBS, but often include dietary changes, lifestyle modifications, and medications. Treatment can help reduce the frequency and severity of symptoms. Keep a record of your symptoms and possible triggers, and see a health care professional if you have ongoing IBS symptoms.