An Overview of Diarrhea Predominant IBS (IBS-D)

Diarrhea predominant irritable bowel syndrome (IBS-D) is a subtype of IBS in which a person experiences frequent episodes of diarrhea with accompanying abdominal pain. Like IBS, IBS-D is a functional gastrointestinal disorder (FGD) in that there is no visible disease, inflammation, or injury to account for its symptoms. Estimates suggest that about one-third of people with IBS experience diarrhea as the predominant symptom.

Symptoms of IBS-D

As opposed to the other IBS subtypes, people who have IBS-D typically experience:

• Frequent bowel movements
• Loose stools
• Feelings of urgency

In addition, people who have IBS-D also have some or all of the following symptoms of IBS:

• Abdominal pain
• Gas and bloating
• A feeling of incomplete evacuation
• Mucus in the stool

According to the Rome IV diagnostic criteria for IBS, symptoms must occur at least once a week, on average, for a period of at least three months.

Some people who have IBS may find that they switch from times of having IBS-D to times of experiencing constipation-predominant IBS (IBS-C).

Others alternate between constipation and diarrhea on a regular basis, which is a subtype known as IBS-mixed type (IBS-M) or IBS-alternating type (IBS-A).

Causes

Although the exact cause of IBS-D remains unknown, researchers are investigating several different possibilities. These include:

• A dysfunction in the brain-gut connection, with possible neurotransmitter involvement
• Food sensitivities
• Gut dysbiosis
• Idiopathic bile acid malabsorption (I-BAM)
• Inflammation in the lining of the gut
• Small intestinal bacterial overgrowth (SIBO)

Treatment 

If you think that you might have IBS-D, please make an appointment with your doctor. There are other serious health conditions that share many of the same symptoms with IBS-D. It is essential to rule these out.

If your doctor concludes that you have IBS-D, they will work with you on a treatment plan. They may recommend over-the-counter treatments or prescribe you a medication. Options include:

• An anti-diarrheal medication, such as Imodium (loperamide)
• An antidepressant to slow down motility and ease pain
• An antispasmodic to reduce gut cramping and pain
• Xifaxan (rifaximin), a targeted antibiotic
• A bile acid binder such as Prevalite (cholestyramine)
• A targeted opioid medication such as Viberzi (eluxadoline)
• Soluble fiber supplements
• Peppermint oil
• Probiotics

In addition, the American College of Gastroenterology recommends all IBS patients try a low-FODMAP diet to see if it helps ease symptoms. IBS-D symptoms may also benefit from other dietary changes, such as:

• Eating smaller meals
• Avoiding high-fat meals
• Avoiding fried foods
• Keeping a food diary 
• Identifying and avoiding your IBS trigger foods

Last, IBS-D symptoms may be reduced through mind/body approaches, with cognitive-behavioral therapy (CBT) and hypnotherapy having the most research backing their effectiveness for IBS.