What Is IBS? Symptoms, Causes, Diagnosis, Triggers & Treatment (Complete Guide)

Have you suspected that you may have Irritable bowel syndrome (IBS) but don’t know whether it is true? This article will give you a comprehensive overview of IBS to help you better understand the condition and determine whether you may need further evaluation by a healthcare professional. 

Let’s dive in and see if anything relates to you. 

IBS is a common digestive disorder that affects the large intestine. It causes symptoms such as bloating, gas, diarrhea, abdominal pain and constipation (1)

Although this condition does not damage the digestive tract or lead to serious complications in most cases, it can significantly affect daily functioning and overall quality of life interfering with a person’s physical, emotional, and social well-being (2)

IBS is classified as a functional gastrointestinal disorder, meaning that the digestive system appears structurally normal and looks healthy during the medical tests but does not function properly. 

Infographic summarizes the irritable bowel syndrome (IBS) symptoms, causes, types, triggers and treatment

IBS Symptoms: Most Common Signs and Warning Symptoms

IBS affects approximately 5-10% of people worldwide (3). However, the true number may be even higher because those affected with digestive symptoms do not seek medical care or receive a formal diagnosis. Some individuals live with symptoms for years and assume that their digestive discomfort is simply normal.

Symptoms of this functional gut disorder vary widely from person to person. Some people experience only occasional discomfort, while others have frequent flare-ups that interfere with daily activities.

Symptoms can also change over time. For example, someone may initially experience diarrhea but later develop constipation or alternating bowel habits.

Most Common IBS Symptoms

Common symptoms include:

  • Abdominal pain or cramping
  • Bloating
  • Excessive gas
  • Abdominal distention (visible swelling of the abdomen)
  • Diarrhea
  • Constipation
  • Alternating diarrhea and constipation
  • Changes in stool frequency or appearance

Abdominal pain is considered the hallmark symptom of IBS. The pain is often related to bowel movements and may improve after passing stool.

Other Possible IBS Symptoms

Some people may also experience additional symptoms such as:

  • Fatigue
  • Nausea
  • Mucus in stool
  • Feeling of incomplete bowel movement
  • Lack of energy
  • Back pain

These symptoms may occur because the digestive system and nervous system are closely connected. Changes in gut function can affect energy levels, mood, and overall well-being.

IBS symptoms may be triggered by several factors, including certain foods, stress, hormonal changes, or disruptions in gut bacteria.

Symptoms That Are NOT Typical of IBS

Although this gastrointestinal condition can cause many uncomfortable digestive symptoms, certain signs are not typical of IBS and may indicate another medical condition.

Contact your healthcare provider if you experience:

  • Blood in the stool
  • Fever
  • Persistent vomiting
  • Unexplained weight loss
  • Symptoms that become progressively worse

These symptoms may require additional medical evaluation to rule out conditions such as:

  • Celiac disease
  • Crohn’s disease
  • Ulcerative colitis
  • Colon cancer

Your healthcare provider may recommend tests such as blood tests, stool tests, imaging studies, colonoscopy, and/or endoscopy to rule out other causes of digestive symptoms.

What Causes IBS?

Many people with IBS want to know exactly what causes the condition. Unfortunately, the precise cause is still unknown.

Researchers believe it develops due to a combination of biological and environmental factors that affect how the digestive system functions (4).

Some of the most commonly proposed contributing factors include:

Gut Microbiome Imbalance

The gut contains trillions of bacteria that help digest food and regulate the immune system. Changes in the composition of these bacteria, known as dysbiosis, may contribute to IBS symptoms (5).

Increased Gut Sensitivity

Some people often have a digestive system that is more sensitive to normal digestive processes. Gas or intestinal stretching that would not cause discomfort in most people may trigger pain in those with IBS (6).

Abnormal Gut Motility

The muscles of the intestines move food through the digestive tract. In IBS, these contractions may be too fast or too slow, leading to spastic bowel and resulting in diarrhea or constipation (7).

Food Sensitivities

Certain foods may worsen symptoms in some individuals. For example, fermentable carbohydrates found in many foods can increase gas production and bloating.

Gut-Brain Communication

The digestive system and the brain communicate through what is known as the gut-brain axis. Stress, anxiety, and emotional factors can influence how the gut functions and may trigger adverse gastrointestinal reactions.

Previous Infections

Some people develop Irritable Bowel Syndrome after a severe stomach infection or food poisoning. This condition is known as post-infectious IBS (8).

What Triggers IBS?

People experience different triggers of adverse gut symptoms, and these can vary from person to person. Understanding individual triggers is an important step in managing the symptoms.  

Food triggers (FODMAPs)

Foods high in FODMAPs can trigger IBS symptoms in some people. These carbohydrates are poorly absorbed in the gut and may lead to bloating, gas, abdominal pain, diarrhea, and constipation (9)

Stress

The gut and brain are closely connected, and increased stress can affect digestion, gut sensitivity, and bowel habits. As a result, many people with this digestive condition notice more bloating, abdominal pain, diarrhea, or constipation during stressful periods (10)

Hormones

Hormonal changes can influence IBS symptoms in some people, especially women. Fluctuations in hormones such as estrogen and progesterone may affect gut motility, digestion, and sensitivity in the gastrointestinal tract. As a result, symptoms may worsen during menstruation, pregnancy, or menopause (11)

Antibiotics

Antibiotics can trigger or worsen IBS symptoms by disrupting the balance of beneficial bacteria in the gut microbiome. In some cases, symptoms may begin after a course of antibiotics or a gastrointestinal infection (12).

Travel / Routine Changes

Disruptions in daily routine, such as altered sleep patterns, different meal timing, dietary changes, and increased stress can all affect gut function and bowel regularity. As a result, many individuals experience bloating, abdominal discomfort, or changes in bowel habits while traveling or adjusting to a new routine .

How IBS Is Diagnosed

Usually, doctors diagnose IBS based on symptoms and by ruling out other digestive conditions.

Many patients undergo several medical tests before receiving an IBS diagnosis. These tests may include blood tests, stool tests, imaging studies, or endoscopy to exclude other diseases.

Healthcare providers commonly use diagnostic guidelines developed by the Rome Foundation.

Rome IV Diagnostic Criteria

According to the Rome IV criteria, IBS can be diagnosed when a person experiences:

Recurrent abdominal pain at least once per week during the past three months

AND at least two of the following:

  • Pain related to bowel movements
  • Changes in bowel movement frequency
  • Changes in stool appearance

In 2026 Rome V updated the criteria to include abdominal discomfort and lower symptom-frequency thresholds. 

  • Rome V now allows abdominal pain or abdominal discomfort, recognizing that many patients describe their symptoms as discomfort rather than pain. 
  • Rome IV required symptoms at least 1 day per week on average. Rome V lowers the threshold to 3 days per month of abdominal pain or discomfort

Test for IBS

Developed by Dr. Mark Pimentel, IBS-Smart test is a home test that can identify if you have IBS due to the infectious gastroenteritis. It is used in people who have IBS-D and IBS-M subtypes and can give a clear picture of diagnosis.

Types of IBS

IBS is classified into different subtypes based on bowel habits.

Understanding the subtype can help guide treatment strategies.

IBS-C (Constipation-Predominant)

IBS-C occurs when constipation is the dominant symptom.

Common features include:

  • Hard or lumpy stools
  • Difficulty passing stool
  • Infrequent bowel movements
  • Abdominal discomfort associated with constipation

More than 75% of bowel movements are typically hard or difficult to pass.

IBS-D (Diarrhea-Predominant)

IBS-D is characterized by frequent loose or watery stools.

Symptoms may include:

  • Urgent bowel movements
  • Loose stools
  • Abdominal cramping or discomfort
  • Increased bowel frequency

More than 75% of stools are loose or watery.

IBS-M (Mixed Type)

IBS-M involves alternating diarrhea and constipation.

People with this subtype experience both hard stools and loose stools at different times.

IBS-U (Unclassified)

Some individuals have IBS symptoms but do not clearly fall into the other categories. These cases are classified as IBS-U.

How Long Does IBS Last?

Chronic condition 

IBS is considered a chronic condition, meaning it is long-term and does not typically go away completely. However, symptoms often come and go, with periods of flare-ups and times of relief. With proper management, many people are able to significantly reduce symptoms and improve their quality of life. 

Flare-ups vs remission 

IBS often follows a pattern of flare-ups and remission. During flare-ups, symptoms such as abdominal pain, bloating, and changes in bowel habits become more noticeable, while remission periods are when symptoms are mild or absent. The frequency and intensity of these cycles vary from person to person. 

Individual variability

Symptoms, triggers, and severity can differ widely from person to person. Because of this variability, effective management usually requires a personalized approach tailored to each individual’s specific symptoms and triggers. 

IBS Treatment: Diet, Medications, Supplements and Lifestyle Changes

Although IBS does not have a cure, symptoms can often be managed successfully through a combination of dietary strategies, lifestyle changes, medications, and supportive therapies.

The best treatment approach varies from person to person depending on symptoms and triggers.

Dietary Approaches

Diet plays a major role in managing IBS symptoms.

Helpful strategies may include:

  • Following a low FODMAP diet
  • Identifying individual food triggers
  • Reducing foods that commonly worsen symptoms, such as fatty foods, caffeine, alcohol, and spicy foods
  • Increasing soluble fiber intake when appropriate

Researchers at Monash University suggest that the low FODMAP diet can improve symptoms significantly in people with IBS.

Lifestyle Changes

Lifestyle habits can also influence digestive health.

Helpful practices include:

  • Managing stress
  • Getting regular physical activity
  • Maintaining a consistent sleep schedule

Stress reduction techniques such as mindfulness, meditation, or yoga may also improve IBS symptoms.

Medications

Doctors may prescribe medications depending on symptoms.

These may include:

  • Antidiarrheal medications
  • Laxatives for constipation
  • Antispasmodics to reduce intestinal cramps
  • Certain antidepressants that help regulate the gut-brain connection

Supplements

Some supplements may provide symptom relief for certain individuals.

Examples include:

  • Soluble fiber
  • Probiotics
  • Peppermint oil capsules

Psychological Therapies

Because the gut and brain are closely connected, psychological therapies may also help manage symptoms.

Examples include:

  • Cognitive behavioral therapy (CBT)
  • Gut-directed hypnotherapy

When to Seek Professional Help

If digestive symptoms are affecting your daily life, it may be helpful to consult a healthcare professional.

A proper evaluation by a gastroenterologist can help confirm whether symptoms are due to IBS and rule out other serious medical conditions, such as Crohn’s disease, ulcerative colitis or celiac disease.

Irritable bowel syndrome (IBS) is a complex digestive condition that can affect every person differently. From abdominal pain and bloating to constipation, diarrhea, and food sensitivities, IBS symptoms can significantly impact daily life. While the exact cause of IBS is not fully understood, factors such as gut microbiome imbalances, stress, hormones, infections, and gut-brain communication all appear to play a role.

The good news is that IBS can often be successfully managed with the right combination of dietary changes, lifestyle strategies, stress management, supplements, medications, and professional support. Understanding your personal triggers and identifying your IBS subtype can help you create a more targeted treatment plan and reduce flare-ups over time.

If you are experiencing ongoing digestive symptoms, it is important to speak with a healthcare provider to rule out other conditions and receive an accurate diagnosis. With the right approach, many people with IBS can improve their symptoms, support gut health, and feel better long term.

Working with a registered dietitian who specializes in digestive health can help identify potential triggers and develop an effective management plan. Schedule a free discovery call to see if we are a good match working together. 

About the Author

Yuliya Gudkova, RDN, LDN is a registered dietitian specializing in gut health and irritable bowel syndrome. She helps individuals manage digestive symptoms using evidence-based nutrition strategies, including the low FODMAP diet.

If you are looking for support in managing IBS symptoms, consider scheduling a consultation to develop a personalized plan for improving your digestive health.

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