Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder that causes symptoms like abdominal pain, bloating, and changes in bowel habits. The symptoms can range from mild to severe, coming and going or changing in intensity over time.
There are three main types of IBS, classified based on whether a person experiences diarrhea, constipation, or both.
Identifying which type of IBS you have ensures your treatment plan effectively manages symptoms and improves your quality of life.
IBS with diarrhea (IBS-D) is the most common form of irritable bowel syndrome, affecting approximately 40% of people with IBS. It is associated with frequent diarrhea episodes.
The exact cause of IBS-D is unknown, though research suggests changes in the gut microbiota—the trillions of bacteria, fungi, and other microbes that live in the intestines and help digest the foods you eat—play a role.
Dysbiosis, an imbalance of the gut microbiota, can change the gut-brain axis. The gut-brain axis is the signaling network between gut microbiota and the brain. With IBS-D, disruptions in the gut-brain axis can cause food to move through the gut too quickly, leading to diarrhea, abdominal cramping, and other symptoms.
Dysbiosis may also make nerves in the intestines more sensitive and hyper-reactive to normal digestive activities, so even the normal movement of food or gas through the intestines can trigger 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 fewer than 25% will be hard or lumpy. Other common symptoms of IBS-D include:
- Sudden, urgent need for bowel movements
- Abdominal cramping, typically relieved after a bowel movement
- Bloating and gas
- Bowel incontinence
- Whitish mucus in stool
These symptoms can have a significant impact on your day-to-day life, leading to fatigue, anxiety, and depression. People with IBS-D report 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 assigned female at birth. It often develops in adolescents and young adults but can affect people of all ages.
While the cause of IBS-C is not entirely understood, several factors likely contribute to its development. Dysbiosis (changes in the gut microbiota) may be a major factor in IBS-C, as well.
Dysbiosis with IBS-C can cause slower digestive motility, meaning food and waste move through the intestines more slowly than usual. This delayed movement allows the large intestine to absorb more water from stool (poop), making stool hard, dry, and difficult to pass.
A low-fiber diet can also contribute to IBS-C. Fiber helps bulk up stool and promote waste movement through the intestines. People with IBS-C often have increased sensitivity to certain foods, like dairy, gluten, and high-fat foods. Even small amounts of these foods may irritate the digestive system, triggering 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 fewer than 25% are loose or watery. Other common symptoms of IBS-C include:
- Persistent abdominal pain or cramping
- Severe bloating and gas
- Straining while trying to have a bowel movement
- Infrequent bowel movements, sometimes fewer than three times per week
- Tenesmus, a sensation of an incomplete bowel movement
While symptoms of IBS-C may improve temporarily after 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 more complex to manage because symptoms can shift unexpectedly. IBS-M affects both males and females 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.
Issues of the gut-brain axis can lead to gut motility imbalance, where the intestines alternate between moving food too quickly (leading to diarrhea) and too slowly (causing constipation). This irregular movement disrupts digestion and makes stool consistently unpredictable.
Factors like emotional stress and certain foods can trigger or worsen symptoms and increase the likelihood of rapid, uncomfortable shifts in bowel habits.
Symptoms
With IBS-M, symptoms fluctuate between constipation and diarrhea. On days when 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 cramping that varies in intensity and location
- Gas and bloating, which can fluctuate as your stool changes
- Urgent need for a bowel movement at times, while other times experiencing difficulty passing stool
- Sensation of incomplete bowel movement
- Mucus in stool
- Feeling uncomfortably full or nauseous after eating a meal
Diagnosing IBS and determining your type involves a thorough medical history and symptom review, a physical examination, and diagnostic tests.
Healthcare providers use the Rome criteria to diagnose IBS. The Rome criteria specifies that to receive an IBS diagnosis, you must experience abdominal pain at least once per week over the last 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:
- Stool test: This involves analyzing a sample of poop to check for infections, inflammation, or the presence of blood. The test can help rule out inflammatory bowel disease (IBD) or bacterial intestinal infections.
- Blood test: A healthcare provider 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 are not typically common with IBS.
- Colonoscopy: A healthcare provider inserts a thin, flexible tube with a small camera into the anus to examine the intestinal lining. This test can help rule out conditions like 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 track how well the muscles move food through the large intestine.
Diagnostic tests can’t diagnose specific IBS types, so it may be helpful to keep a symptom log to help your healthcare provider determine which type you have. This log should include details on the following:
- Stool frequency
- Stool consistency
- Pain or discomfort you experience
- Diet, exercise, stress, and sleep levels (to help identify symptom triggers)
See a healthcare provider if you experience persistent IBS symptoms. While occasional diarrhea and constipation are common, ongoing symptoms may be a sign 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 like antidiarrheal medicines, anticholinergic medicines that control intestinal spasms, or laxatives for treating constipation. Probiotics or fiber supplements may also help improve the gut microbiota and promote healthy bowel movements.
Certain symptoms are a red flag for more serious conditions that require prompt medical attention. See your healthcare provider as soon as possible if you experience:
- Bloody stools
- Severe or persistent pain
- Nausea or vomiting
- Fever
- Abdominal pain and/or diarrhea at night
- Unintentional weight loss
It’s not always possible to prevent irritable bowel syndrome, but certain lifestyle changes and dietary habits may help reduce symptoms or prevent them from worsening:
- Eat a balanced diet: A diet with smaller, more frequent meals may help manage IBS symptoms. Incorporating more soluble fiber—found in fruits, beans, and oat products—can improve stool consistency and frequency. A low-FODMAP diet might be helpful. It involves avoiding foods high in certain carbohydrates that are more difficult to digest, including dairy, wheat and rye products, and certain fruits.
- Manage stress: Stress and psychological distress can trigger or worsen IBS symptoms. Stress management techniques like 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 by IBS type but often include dietary changes, lifestyle modifications, and medications. Treatment can help reduce the frequency and severity of symptoms. Keep a log of your symptoms and possible triggers, and see a healthcare provider if you experience ongoing IBS symptoms.
