An older study in 200 adults found that those with diarrhea-predominant IBS had, on average, 12 bowel movements weekly — more than twice the amount of adults without IBS ( 8 ). Accelerated bowel transit in IBS can also result in a sudden, immediate urge to have a bowel movement.

The signs and symptoms of irritable bowel movement are alternating episodes of diarrhea and constipation, frequent changes in bowel habits, bloating, abdominal cramps, sudden urge to pass stools, passing pellet-like stools, and changes in the frequency of passing stools. It can lead to complications like malabsorption, weight loss, vomiting, anemia, and rectal bleeding. It is triggered by stress, the menstrual cycle, and the intake of dairy products.

In some cases, the symptoms are relieved by bowel movements. People with IBS, more commonly than others, have gastroesophageal reflux, symptoms relating to the genitourinary system, fibromyalgia, headache, backache, and psychiatric symptoms such as depression, sleep disorders, and anxiety.

Instead of slow, rhythmic muscle movements, the bowel muscles spasm. That can cause diarrhea or constipation. Another theory suggests it may involve chemicals made by the body, such as serotonin and gastrin, that control nerve signals between the brain and digestive tract.