Random (Intermittent) Diarrhea: 7 Causes (Dr. Farahat).

Our content is not intended nor recommended as a substitute for medical advice by your doctor. Use for informational purposes only.

Common causes of random (intermittent) diarrhea include:

  • Food intolerance.
  • Irritable bowel syndrome.
  • Medications such as metformin, proton pump inhibitors, and laxative abuse. 
  • Stress and anxiety.
  • Exagerated gastro-colic reflex. 
  • Colorectal cancer
  • Other causes include Diabetes Mellitus, celiac disease, inflammatory bowel disease, endocrinal disease, and some rare intestinal diseases.

The details are explained below.

1- Food intolerance (Especially lactose intolerance).

Your digestive system may have difficulty digesting certain types of food. Food intolerance is more common than you think. Up to 15-20% of people are intolerant to food.

The reasons why we included food intolerance as the first cause of random diarrhea:

  • It is very common.
  • Diarrhea is related to the ingestion of the offending food. So, diarrhea can randomly affect you when ingesting certain foods.

Food intolerance can be due to a single type of food or a group of foods. The most common examples of food intolerances are:

1- Lactose intolerance (intolerance to milk and other dairy products.

2- Caffeine intolerance (in coffee, chocolate, …etc).

3- FODMAPs (a group of short-chain carbohydrates that ferment rapidly inside your intestine and may cause random diarrhea). Most people with irritable bowel syndrome are intolerant to FODMAPs.

4- Fructose intolerance (present mainly in honey and fruits).

5- Gluten intolerance (celiac disease).

6- Other types of food intolerance, such as alcohol intolerance, amines, sulfites, eggs, …etc.

Symptoms (how to suspect food intolerance as a cause of random diarrhea)

  • Diarrhea every time you eat the offending food (random diarrhea).
  • Abdominal colics (ramps).
  • Gas, flatulence, and bloating.
  • Nausea with or without vomiting may also occur randomly.
  • The symptoms start shortly after eating and may last for days.

Another type of food sensitivity is called food allergy. Food allergy differs from a food allergy but can also cause random attacks of diarrhea.

The table below summarizes the differences between food intolerance and food allergy.

Food intoleranceFood allergy
Affects 15-20% of the populationAffects nearly 2-5% of adults
Difficulty digesting certain types of food (not immune-mediated allergy).An immune-mediated reaction to certain foods or food components.
Causes “random acute” or “chronic” attacks of diarrhea (which can be bright yellow & watery).Usually causes random acute attacks related to the ingestion of offending food.
Intestinal symptoms: diarrhea, extensive gas, bloating, and abdominal painIntestinal symptoms are the same
No extra-intestinal symptomsExtraintestinal symptoms include rashes, urticaria, swollen lips, face, or life-threatening allergic reactions.
The severity of your symptoms is proportional to the amount you eat from the offending food.Even trace amounts of the offending food can produce severe symptoms.

Common offending foods:

  • Lactose intolerance (dairy products).
  • Fructose malabsorption.
  • Alcohol intolerance.
  • FODMAP intolerance (as with People with IBS).

Common offending foods: (examples)

  • Raw meat, seafood.
  • Nuts, peanut
  • Mustard.
  • Rice
  • Some vegetables and fruits.


2- Irritable bowel syndrome.

Irritable bowel syndrome is an underdiagnosed condition. Research estimates that up to 40% of IBS sufferers don’t know they have it. This is because the symptoms are usually moderate and non-specific.

Sporadic attacks of diarrhea and abdominal pain that come and go may suggest IBS. The principal feature of IBS is abdominal pain. Having random attacks of diarrhea without abdominal pain precludes IBS.

How to suspect IBS (symptoms):

  • Abdominal pain that is recurrent at least one day per week (for severe months).
  • The pain is associated with bowel movements (the pain improves or worsens after you poop).
  • The pain is associated with a change in stool form (becoming more loose or hard).
  • The pain is associated with a change in stool frequency (diarrhea or constipation).
  • The symptoms may come and go randomly.
  • Triggers are usually food and psychological stress.
  • Random diarrhea with mucus is frequent with IBS.

3- Medications.

Hundreds of drugs can lead to diarrhea. Try to remember any medication intake related to your diarrhea.

Drugs are often overlooked as a cause of chronic or sporadic attacks of diarrhea. Diarrhea is a reported side effect of more than 700 medications.

Check your list of medications for any medications that can cause random diarrhea:

  • Metformin:
    A famous anti-diabetic drug used in patients with type 2 diabetes mellitus.
    Metformin-induced diarrhea is very common, especially if you take high doses.
  • Antibiotics:
    Antibiotics may cause a permanent change in the microbial environment inside your gut. This predisposes to disturbances in your digestion.
    Chronic diarrhea or random attacks of diarrhea, distention, bloating, and even IBS may result from antibiotics.
    The most common antibiotics causing diarrhea include penicillins, cephalosporins, and clindamycin antibiotics. A more detailed list is here.
  • GERD and gastritis medications.
    Proton pump inhibitors include Esomeprazole (Nexium®), Omeprazole (Prilosec®), and others.
    When used for long periods, these medications may disturb the natural microbial environment inside your gut. As a result, random attacks of diarrhea and other digestive symptoms may result.
  • Immuno-suppressive drugs.
    Treatment of immune-mediated disease involves medications that inhibit your immunity. Medications such as methotrexate (Trexal®), Mycophenolate mofetil (CellCept®), and others may cause diarrhea.
    Consult your doctor about random diarrhea attacks if you have any immune-medicated disease. Examples include Systemic lupus erythematosus, Rheumatoid arthritis, systemic sclerosis, …etc.
  • Chemotherapy drugs
    cancer patients who receive chemotherapy may experience severe diarrhea. However, milder forms or random attacks of diarrhea may also occur.
  • Furosemide (Lasix®)
    Furosemide is a diuretic medication that is used for hypertension and heart disease.

4- Stress, anxiety.

You’re not alone if you get diarrhea in stressful or anxiety-producing situations. Psychological stress massively affects your digestion.

You may experience random diarrhea attacks solely due to stress.

Stress and anxiety can affect your digestive system in multiple ways. For example, anxiety is way more common in IBS sufferers than in the general population (reference).

If the random diarrhea is related to times of worry, anxiety, or stress, think of it as a symptom of psychological dysfunction.

If you are unsure about the relation, consult your doctor or gastroenterologist.


5- Exagerated gastro-colic reflex.

When your stomach receives food, it signals your colon to move more (reference).

This happens physiologically & helps the colon empty to receive the waste from the next meal.

Over-reaction of your colon can happen due to abnormal hypersensitivity of its wall or psychological stress (reference).

Abnormally exaggerated gastro-colic reflex can cause symptoms such as random diarrheal attacks, the urge to poop after meals, and abdominal pain.

Irritable bowel syndrome is thought to occur due to an exaggerated gastro-colic reflex.

Learn more about the gastro-colic reflex.

6- Post-cholecystectomy diarrhea.

The removal of your gallbladder can result in diarrhea. A condition called “post-cholecystectomy diarrhea.

This condition is common and can affect up to 20% of people after gallbladder removal. Random attacks of diarrhea can happen because your colon cannot handle excess bile acids. (reference)

A characteristic feature of this type of diarrhea is a severe urge to poop. It may become severe to the degree that soiling accidents occur.

The diarrhea attacks are related to the ingestion of fatty foods. Post-cholecystectomy diarrhea can last anytime between a few weeks to several years.

Consult your doctor if you believe that random diarrhea is related to cholecystectomy.

7- Colorectal cancer.

The most common symptom of colon cancer is a prolonged change in bowel habits (random attacks of diarrhea or constipation).

Other symptoms include blood in stool, weight loss, lost appetite, unexplained fever, or anemia.

Contrary to the popular belief that colon cancer causes pain, abdominal pain is uncommon with colon cancer.

Isolated abdominal pain is present only in 3.8% of colorectal cancer patients (reference).

If you are older than 40, getting a colonoscopy screen is better.

Prevalence of symptoms in colon cancer patients (reference):

  • Change in bowel habits (Unexplained diarrhea or constipation): in 75% of patients with colon cancer.
  • Blood in the stool (dark or bright red): 50%.
  • A sense of rectal mass: in 25%.
  • Anemia (iron deficiency): in 10%.
  • Isolated abdominal pain: only 3.8% of cases.
  • Other symptoms such as weight loss, unexplained fever, nausea, and anorexia are also present.

Learn more about colorectal cancer and your gut symptoms.

7- Others (less frequent causes of random diarrhea).

A- Diabetes Mellitus.

Damage to the nerves supplying your gut can result from long-lasting uncontrolled diabetes. (reference)

This can speed up (or slow down) your gut motility. Changes in bowel habits, such as random diarrhea or constipation attacks, are common if you have diabetes.

B- Celiac disease.

Celiac disease is the most extreme form of food intolerance. It affects about 1%  of people (reference).

Celiac disease is an intolerance to a protein found in wheat, rye, and barely. The protein is called Gluten.

Eating the offending foods can result in diarrhea (chronic or random attacks). Learn more about celiac disease.

C- Endocrinal diseases.

The below condition is less frequent and have more complex symptoms. Often, they have multi-system symptoms, and they are not confined to diarrhea. Consult your doctor if you have troublesome diarrhea of unclear cause.

  • Thyrotoxicosis (hyperactive thyroid gland).
  • Carcinoid syndrome.
  • Medullary carcinoma of the thyroid gland.
  • Gastrinoma.
  • Vipoma.
  • Glucaginoma.
  • Somatostatinoma.
  • Systemic mastocytosis.
  • Addison’s disease.

Learn more HERE and HERE.

D- Less common intestinal diseases

  • Inflammatory bowel disease (Crohn’s disease and ulcerative colitis).
  • Tropical sprue.
  • Whipple’s disease.
  • Eosinophilic gastroenteritis.
  • Microscopic colitis.
  • Intestinal lymphoma.
  • Mesenteric ischemia.
  • Radiation to the intestines.
  • Chronic giardiasis.
  • Intestinal lymphangiectasia.

MORE: 7 Causes of Constant Loose Stool every Day.