Overactive Bowel Movements (Hyperactive Bowel) Causes

The term diarrhea which indicates the passing of more than 200g or 200ml of stool usually in more than three bowel movements within a 24 hours does not account for every change in bowel habit. With diarrhea, the stool is either watery or of a loose consistency and often accompanied by other symptoms like urgency to defecate, abdominal cramping, excessive flatulence, abdominal bloating and bowel incontinence in severe cases. At times a person may experience frequent bowel movements, where the stool is of a normal consistency. In this case it does not fit into the category of diarrhea but cannot be ignored as being more frequent than normal.

It is often referred to as an overactive bowel leading to frequent bowel movements since it cannot be clearly defined clinically. While this reference is not incorrect, it is important not to detract from diarrhea itself, which should be investigated and treated promptly. In the true sense of the word, an overactive bowel is not pathological and will not lead to any complications like dehydration if it persists for a long period of time. Nevertheless, any disturbance in bowel habit in manner that deviates from the norm for a person needs to be carefully assessed and monitored.

Nutrition and Lifestyle

The physiological factors that may contribute to this change is discussed further under frequent bowel movements.

  • Food – certain foods, particularly spicy foods, overeating, frequent eating
  • Fluid – excessive fluid intake may regulate or restore normal bowel movements
  • Fiber – high fiber intake may regulate normal bowel movements but can also contribute to excessive gas or diarrhea
  • Stress – anxiety
  • Stimulants – nicotine, caffeine
  • Exercise – moderate physical activity regulates normal bowel habit while excessive strenuous activity may cause diarrhea

Discontinuing or removing any of the abovementioned factors will restore the bowel movements to the norm.

Functional Disorders

Irritable bowel syndrome (IBS) is probably the best known functional bowel disorder. This means that there is no detectable abnormality that can be attributed to the change in bowel habits as well as the other symptoms that is often present like abdominal cramping, abdominal bloating and abdominal distension. Stress, stimulants and certain foods are known to exacerbate the condition. The exact cause of IBS is unknown but it is associated with a disruption in gastrointestinal motility.

IBS may be diarrhea-predominant or constipation-predominant. Often there may be an alternation between the two states. In terms of the diarrhea-predominant type, a person will not experience diarrhea throughout the course of the disease. Instead there are frequent episodes of diarrhea but most patients will report overactive bowels, meaning bowel movements of 3 to 5 times a day (sometimes more) that is of a normal consistency. Most patients experience this after eating, even in the absence of stress, known trigger foods or stimulant use.

Drugs and Diseases

The pathological causes of an overactive bowel can be divided into acute or chronic and most will eventually lead to diarrhea. Some of these causes include :

  • Drugs
  • Endocrine
    • Hyperthyroidism
    • Endocrine tumors
  • Bowel Diseases and Bowel Surgery
    • Inflammatory bowel disease (IBD) – ulcerative colitis, Crohn’s disease
    • Gastric bypass surgery
    • Intestinal resection (short bowel syndrome)
    • Whipple surgery
  • Cancer
    • Colon / colorectal
    • Small intestine

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