Irritable Bowel Syndrome (IBS) Symptoms and Triggers

Irritable bowel syndrome (IBS) is a common disease of the digestive tract. It causes abdominal pain and changes in bowel movements. Professionals classify it as a “functional disorder.” This is because it affects the intestines’ normal function, the sensitivity of the nerves from the gut, and the way the brain controls gut function. However, there are no “organic” changes seen with an endoscope, X-rays, or other tests.

IBS is a diagnosis of exclusion. Doctors diagnose the condition only when they rule out celiac and Crohn’s disease. Research from the last few decades shows the condition is associated with gut dysbiosis or altered gut flora, even if standard tests don’t detect gut changes. These changes play important roles in the development of symptoms.

In this article, we’ll review common symptoms and their triggers.

ibs - woman clutching her stomach in pain

IBS Symptoms

IBS symptoms seem to come and go; they are not constant. IBS has a pattern of recurring symptoms of periods of flare-ups and remissions. These symptoms also vary in intensity. One characteristic of IBS symptoms is they often happen when the individual is awake.

People usually experience symptoms in their 20s, but they can show up later in life.

Abdominal pain is a key symptom. It feels like a dull ache or cramps in the lower abdomen. This pain may get worse after a meal or a bowel movement.

Those with irritable bowel syndrome will experience changes in bowel movements. Some people experience diarrhea (IBS-D) with loose stools. Others experience constipation (IBS-C) with hard, lumpy bowel movements. Some experience both diarrhea and constipation, known as IBS with mixed movements (IBS-M).

There is another classification, “IBS unclassified” for those who don’t meet the criteria. These individuals may notice mucus in the stools and feel they cannot completely evacuate bowels during defecation.

Other digestive symptoms include bloating, excess gas, and nausea.

Upon physical examination, abdominal tenderness may be present.

Neurological Symptoms

IBS symptoms affect more than just the digestive tract. Since there is a connection between the gut and brain via the gut-brain axis, many experience neurological symptoms. These include fatigue, brain fog, sleep problems, and headaches.

People with IBS experience stress, anxiety, and depression more frequently than others. Stress in particular is a well-known trigger for flare-ups.

Severe Symptoms

There are some non-typical symptoms that suggest other digestive conditions are present. These include fever, bloody stools, weight loss, iron deficiency anemia, a palpable lump in the abdomen, and vomiting. If you experience these, seek medical attention for further investigation.

Abdominal pain associated with defecation is likely of gut origin. If you experience this pain from exercise, movement, menses, or urination, there may be another underlying cause.

ibs - doctor talking to patient


When testing for IBS, doctors use lab tests, ultrasounds, and X-rays to rule out other digestive conditions. They then use Rome IV criteria to confirm a diagnosis.

According to the Rome IV criteria, there must be abdominal pain experienced at least one day weekly over the last three months and one of the following:

  1. Abdominal pain related to bowel movements (pain either improves or gets worse)
  2. The pain correlated with changes in bowel movement (constipation and/or diarrhea)
  3. Abdominal pain is associated with changes in bowel consistency
ibs - hamburger and soda

IBS Triggers

Since there isn’t a cure for IBS, people must learn to live with it and manage the condition. One way to do this is to avoid flare-up triggers.


Some foods can trigger IBS symptoms and flare-ups. In the case of IBS-C, the most common foods are bread and bakery products made with refined grains. Processed foods, dairy products, and a high amount of protein can also cause a flare-up. Carbonated drinks, coffee, and alcohol may also trigger an episode of IBS-C.

Foods high in fiber can aggravate IBS-D; particularly insoluble fiber found in vegetables and fruits. Large meals, fried food, high-fat diets, dairy products, and wheat are also culprits. Coffee, alcohol, chocolate, carbonated drinks, and foods with fructose and sorbitol also contribute.

Not only the foods, but the way a person eats can also worsen symptoms. Someone with the condition may experience symptoms when they eat too quickly or while driving. Chewing gum and stress can also worsen symptoms.

Stress and Anxiety

Stress and anxiety are key triggers for flare-ups. Sleep problems often co-exist and further aggravate the condition. Stress can come from various sources like work, home, financial insecurity, or relationship issues. Childhood history of verbal, emotional, or physical abuse and certain personality traits have been linked to IBS.

Other Triggers

Some medications, particularly antibiotics, antidepressants, and cough medicines with sorbitol can trigger symptoms. Hormonal changes related to menses can also worsen symptoms in women.

Infections may also act as triggers. Up to one in three cases are “post-infectious” IBS. The disease develops after an infection such as the stomach flu. Researchers believe the gut inflammation, changes in intestinal permeability and alteration of gut flora from infection trigger the development.

If you have IBS, avoid triggers of flare-ups and talk to your doctor about how to manage it. There are certain IBS diets you can try and natural supplements to relieve symptoms as well.