Diarrhea IBS (IBS-D) Causes, Symptoms, Treatment, Diet

It is often self-diagnosed but irritable bowel syndrome presents with specific signs and symptoms and has to meet with certain criteria in order to be diagnosed. Most people think it is a condition associated with frequent bowel movements and diarrhea but there are different types of IBS and various other symptoms like abdominal cramps, gas, bloating and mucus in the stool.

What is IBS-D?

IBS-D stands for diarrhea-predominant irritable bowel syndrome (IBS). It is one of the four bowel movement patterns seen in irritable bowel syndrome. The other three are constipation-predominant IBS (IBS-C), mixed diarrhea and constipation IBS (IBS-M) and alternating constipation and diarrhea IBS (IBS-A). Many IBS sufferers may experience change in sub-types with about 1 in 3 switch between IBS-C and IBS-D.

The exact cause of IBS is unknown and there is no cure for it. However, a combination of dietary and lifestyle measures are effective in managing the condition. Sometimes drugs may be prescribed for severe cases in order to reduce the frequency of attacks and minimize the intensity of symptoms. It is important to note that irritable bowel syndrome is not a psychogenic condition although it may at times be aggravated by anxiety and psychological stress.

Causes of IBS-D

The exact cause of irritable bowel syndrome, irrespective of the type, is unclear. It is classified as a functional bowel disorder meaning that the condition is due to an alteration in physiology but not an actual disease process (pathology) or structural abnormality. Functional bowel disorders are only diagnosed when other related conditions have been investigated and excluded as a possible cause of the symptoms.

It appears that the intestinal motility is altered in irritable bowel syndrome. In the cases of IBS-D the problem may be that the muscles that are responsible for intestinal motility are hyperactive. As a last the bowel transit time (movement of food and waste through the bowel) is increased. However, there are many theories about the mechanism behind IBS which may therefore also to diarrhea-predominant IBS.

Although many possible causes have been postulated, the exact cause of irritable bowel syndrome is still unknown. There are instances where it arises after a bacterial infection of the gastrointestinal tract, as is the case with Campylobacter or salmonella. Food intolerances, anxiety, depression and genetics are some of the other risk factors that have also been identified. However, it is important to understand that IBS is not an infectious disorder, food intolerance or psychological condition.

Signs and Symptoms

Abdominal pain is characteristic feature of IBS irrespective of the type of bowel pattern. It is believed to be due to spasms of the intestinal muscles as well as visceral hyperalgesia where a person is more aware of the sensations within the bowels. The pain is often relieved by a bowel movement but this is not always the case. It is abdominal pain and cramping that is the hallmark of IBS and not the alteration of bowel habit.

Alterations in bowel pattern is the other major symptom. With IBS-D this is bouts of diarrhea. As is the case with any type of irritable bowel syndrome, the symptoms only appear for periods of time and then resolve. IBS is a chronic condition marked by episodes of acute flareups.

The diarrhea may not always occur in the same way as diarrhea with infectious gastroenteritis for example. Instead the bowel movements may be very frequent, a person may have too many bowel movements in a day although the stool consistency is normal and it may occur after certain triggers like shortly after eating.

Other symptoms that occur with IBS includes mucus in the stool, excessive flatulence, a bloated sensation and abdominal distension.

Diagnosis of Diarrhea IBS

The diagnosis of IBS can be difficult. Firstly it is important that various diagnostic investigations are conducted to exclude various diseases that may present with similar symptoms, such as inflammatory bowel disease (IBD), lactose intolerance and even colorectal cancer. In fact many people do not understand the difference between IBS and IBD, often thinking it is the same condition.

Therefore investigations like a colonscopy, barium meal x-ray, CT scan and even MRI may be conducted. However, this is not to diagnose irritable bowel syndrome but instead to exclude other conditions. Secondly, once these investigations confirm the absence of other diseases then the symptoms may be assessed to see if it meets with any specific criteria that is considered for IBS diagnosis, namely the Rome criteria or Manning criteria.

Treatment of IBS-D

There is no cure for irritable bowel syndrome (IBS) irrespective of the type. Dietary and lifestyle measures are the cornerstone of managing irritable bowel syndrome, reducing the frequency of flareups and minimizing symptoms. Medication may be prescribed for symptomatic relief and management but is usually reserved for severe cases. These drugs include:

  • IBS agents such as eluxadoline and lubiprostone to reduce symptoms.
  • Anticholinergic agents such as dicyclomine and hyoscyamine to reduce the cramps.
  • Antidiarrheal agents such as diphenoxylate and loperamide to reduce and stop diarrhea.
  • Tricyclic antidepressants such as imipramine and amitriptyline help with reducing pain.

Other drugs may also be prescribed but this is usually off-label, meaning that the drug in question is not specifically indicated for irritable bowel syndrome but may help with managing the condition. There have been varying reports associated with managing IBS with probiotics and should be tried on an individual basis.

Diet for Diarrhea IBS

Dietary management of irritable bowel syndrome is highly individualistic. Some sufferers may have rare and unusual triggers that does not seem to be a problem for the majority of IBS sufferers. Therefore a food diary should be kept and an elimination diet should be attempted. However, there appears to be a variety of foods that may serve as a trigger and exacerbate the symptoms of diarrhea-predominant IBS. These general dietary measures includes:

  • Increasing fiber intake and even using fiber supplements where necessary.
  • Avoiding caffeine in foods and drinks that have high quantities of it, such as coffee.
  • Minimizing the intake of gluten-rich foods where gluten intolerance appears to be a problem.
  • Reducing milk and dairy intake where lactose intolerance seems to be a concomitant problem.

Read more on IBS diet and lifestyle.


  1. emedicine.medscape.com/article/180389-overview
  2. www.webmd.com/ibs/guide/default.htm

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