Potential Causes for Changes in Bowel Habits | Knowledge is Power


A Brief Summary of the Most Common Causes of Diarrhea and How to Accurately Diagnose and Treat

by Amy White FNP MSN BSN RN Amy White FNP MSN BSN RN (New)

Specializes in Gastroenterology. Has 18 years experience.

How To Diagnose And Treat Common Causes Of Diarrhea

Potential Causes for Changes in Bowel Habits | Knowledge is Power

Loose stools, or diarrhea, can be annoying, frustrating, and downright disruptive to everyday life. We are going to look at several potential causes for this change in bowel habits that can be addressed and treated effectively so life can be more enjoyable.

  • Irritable Bowel Syndrome (IBS)
  • Celiac Disease (CD)
  • Infectious
  • Microscopic Colitis (MC)
  • Bile Acid Diarrhea (BAD) or Bile Acid Malabsorption (BAM)
  • Inflammatory Bowel Disease (IBD)

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome is a functional disorder, meaning gut irritability can often occur related to certain stressors in life, such as stress, anxiety, depression, and even food indiscretion. Typically, IBS is characterized by abdominal cramping or pain and either diarrhea, constipation, or a combination of both. In all patients with suspected IBS, it is necessary to rule out other etiologies that could be more life-threatening if not diagnosed or treated. Stool studies should be obtained to rule out infectious and inflammatory types of diarrheas, this is paramount before an IBS diagnosis is given. Anti-spasmodic medications such as Levsin or Bentyl can be used to help with IBS symptoms. If a patient has IBS with constipation, I would avoid anti-spasmodic medications, a common side effect can be constipation. 

Celiac Disease (CD)

Celiac disease can also produce loose stools, but is typically associated with weight loss as malabsorption is a key component of this disease.  Celiac disease can be genetic and is characterized as an immune disorder triggered by an environmental agent – gluten. It is vital to accurately diagnose CD because this untreated disease can put the patient at risk for lymphoma and gastrointestinal cancer. Treatment can be simple yet complex. Avoid gluten in food (typically wheat, rye, and barley) as well as non-conventional items such as shampoo, beer, candy, deli meats, and more.


Infectious diarrhea is somewhat easier to diagnose. Patients often come in complaining of urgent diarrhea for 24-48 hours often preceded by vomiting. This can be bacterial (E.Coli, Salmonella, C.diff, Campylobacter, or Shigella) or viral (Rotavirus, Norovirus, Adenovirus, or Astrovirus) in nature. Food poisoning is categorized as infectious diarrhea as well. This type of diarrhea typically comes as fast as it goes but can linger as what is known as post-infectious IBS, where diarrhea can come and go for a period of 4-6 weeks after the virus or bacteria has purged from the gut. This takes patience and maybe the use of an antispasmodic (Levsin or Bentyl) and probiotics to help restore gut flora. Hydration for this type of diarrhea is key.

Microscopic Colitis (MC)

Microscopic colitis is a chronic inflammatory disease of the colon that can occur in middle-aged to elderly patients. When a colonoscopy is performed, no visual inflammation is typically seen, however, the pathology reveals somewhat of a different picture. Once microscopic colitis is diagnosed, we urge patients to avoid NSAIDs and smoking as these have been shown to play a contributing role. Budesonide (a bowel-specific steroid) is a medication that is typically started then tapered over 3 months. Some patients do remarkably well after finishing the taper but others need to resume the lowest possible dose to keep diarrhea at bay. If patients don’t respond completely to budesonide only, concomitant therapy with cholestyramine can be used. Most patients do remarkably well on budesonide alone and often sing your praises when this condition has been diagnosed and treated. 

Bile Acid Diarrhea (BAD) or Bile Acid Malabsorption (BAM)

Bile acid diarrhea or bile acid malabsorption arises when the intestines are unable to absorb bile acids properly, therefore, resulting in diarrhea. Patients can complain of diarrhea many years after gallbladder removal. When they come to the office complaining of diarrhea, the thought of it possibly being from prior cholecystectomy never crosses their mind, but this should be on this list of differentials because when the gallbladder is removed, bile acid can dump into the gut thereby causing diarrhea. Colestipol is a great medication to help absorb bile acids and to help thicken stools.

Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease is an umbrella term for Crohn’s disease or Ulcerative colitis. These diseases can produce loose stools as well. Crohn’s disease typically also produces right lower quadrant (RLQ) pain while UC manifests with bloody diarrhea. Fecal calprotectin (stool study) and colonoscopy help to diagnose these diseases. Medications are typically employed such as 5-ASA drugs (Mesalamine), 6-MP drugs (Mercaptopurine), Azathioprine, or even biologics such as Humira or Remicade. Inflammatory bowel disease is a complex autoimmune disease and must be treated as soon as possible. If patients wait too long, severe cases may lead to a total colectomy.

As clinicians, diarrhea can lead us down many paths to finding the correct diagnosis for our patients. Accurate diagnosis in a timely manner can help the patient regain control of their life by employing the best possible treatment regimen.



Amy White FNP MSN BSN RN has 18 years experience and specializes in Gastroenterology.

2 Articles   5 Posts

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6 Comment(s)


Specializes in retired LTC. 7,641 Posts

I enjoyed this article. EASY READING. Not super technical which after 36+ years practice and now 10+ years post retirement  I esp appreciate.

Next is the Constipation article with discussion on mixed S&S. YES?


Specializes in Gastroenterology. Has 18 years experience. 2 Articles; 5 Posts

Thanks for your feedback! I will definitely work on a constipation article! Great idea! 


Specializes in retired LTC. 7,641 Posts

TY for your style. Many articles posted here are just too technical for easy reading. I believe they were prob papers required for some school classes. Excellent information, but I just want to read & absorb 'the important stuff'.

There are some members here who'll provide succinct info when questions are asked of them. These are the best information sources.  Readers here are interested to learn. 


Specializes in Gastroenterology. Has 18 years experience. 2 Articles; 5 Posts

amoLucia, I am starting my nurse writing business and website. Can I use your comment on my article as a testimonial on my website page? 


Specializes in retired LTC. 7,641 Posts


At this stage of my prof career, I'm a 'life long learner'. But I want my readings 'easier & peasier' on a prof level. I'd believe nsg students or new nurses feel the same. I want to learn but not for a dissertation.


Specializes in Gastroenterology. Has 18 years experience. 2 Articles; 5 Posts

Constipation article posted Friday! Check it out! Thanks for suggesting!