Chronic diarrhea is usually the result of irritation occurring along the digestive system, which can be caused by conditions like food intolerances, IBS, pancreatic disease, bowel cancer or cystic fibrosis. It can also be the side effect of medications or eating specific foods (and having a food allergy).

Chronic diarrhea is characterized by an increased number of soft stools per day that lasts for greater than or equal to 4 weeks. It can be caused by microbial infections, food intolerances, intestinal inflammation or medication.

To identify the cause of the chronic diarrhea and to know how to treat it, you should see your doctor for assessment. He or she will review all associated symptoms and may order further testing (like bloodwork or stool tests) to help pinpoint a diagnosis.

What causes chronic diarrhea?

The most common causes of chronic diarrhea are:

1. Food intolerances or allergies

Some intolerances, like lactose or gluten intolerances, or allergies, like a milk protein allergy, can cause irritation or inflammation along the intestinal tract. This can lead to chronic diarrhea, although the diagnosis of this type of condition can take some time.

What to do: You should see your doctor for evaluation if you notice persistent diarrhea. To determine if you have an intolerance or allergy, the doctor may order antibody bloodwork, skin testing or stool testing.

Learn about gluten intolerances specifically and the symptoms associated with this condition.

2. Intestinal infections

Some intestinal infections caused by parasites (like giardiasis, amebiasis or ascaridiasis) or bacteria or viruses (like rotavirus) can cause chronic diarrhea if they are not detected early on. Generally speaking, intestinal infection can cause symptoms like abdominal pain, increased gas, fever, and vomiting. Learn more about symptoms associated with intestinal infections.

What to do: Treatment for intestinal infections consists of rest, hydration and a light diet. Depending on the cuase of infection, the doctor may also prescribe medication like antibiotics or antiparasitics to eliminate the harmful microorganism.

Therefore, if you symptoms persist for more than 3 days or if you additionally have a high fever or bloody stool, you should see your doctor for assessment. Read more about about ways you can treat intestinal infections at home.

3. Irritable bowel syndrome

Irritable bowel syndrome, or IBS, is condition characterized by inflammation of the intestinal villi. It can cause chronic diarrhea, excess gas, abdominal pain and bloating. These symptoms will vary in intensity and can appear very suddenly. They usually persist for a whole before resolving.

What to do: If IBS is diagnosed, you should be followed by a gastroenterologist. Diagnosis is confirmed by evaluating the presenting symptoms and through testing like a colonoscopy, CT scan and stool test.

Treatment usually consists of following a specific diet that is low in fat and sugar. In some cases, the doctor may prescribe medication to help manage symptoms. Learn more about the IBS diet your doctor may recommend and how to get started.

4. Medications

There are some medications that can alter bacterial flora, intestinal flow and the villi in the intestines. Playing with these factors can cause a laxative effect. This is particularly common when medication is taken at doses higher than indicated.

Some medications that can cause chronic diarrhea include antibiotics, some antidepressants, cancer medication, antacids, and proton pump inhibitors.

What to do: If the diarrhea is caused by antibiotics, you can achieve some relief by also taking probiotics. These can be purchased at pharmacies, and work by maintaining intestinal bacterial levels so that the bowels continue to function normally.

If your diarrhea is caused by other medications, you should follow-up with your prescriber and advise them you are experiencing diarrhea as a side effect. You should also aim to have a light diet and drink plenty of fluids.

Check out the natural probiotic foods that you can add to your diet when you are taking medications that may cause diarrhea.

5. Intestinal disease

Intestinal illnesses, like Crohn’s disease, ulcerative colitis, enteritis, or celiac disease can also cause chronic diarrhea. These conditions are associated with chronic inflammation in the intestines, and therefore you may experience other gastrointestinal symptoms as a result.

What to do: If you suspect you may have an intestinal disease, you should see your doctor for assessment, and possible testing and treatment. If a diagnosis is confirmed, you may benefit from a consult with a registered dietitian, to incorporate an appropriate diet into your treatment approach.

6. Pancreatic illness

Pancreatic illnesses, like pancreatic failure, chronic pancreatitis or even pancreatic cancer, are associated with difficulties producing or transporting sufficient amounts of digestive enzymes. These enzymes are required for adequate breakdown and absorption of nutrients. Any insufficiencies or dysfunction can lead to changes to the absorption of fat, which can lead to a chronic diarrhea.

Read more about the symptoms of pancreatic cancer that are specific to this condition.

What to do: In these cases, you should see a registered dietitian to formulate a meal plan that can promote better nutrient absorption without weight loss or malnutrition. A custom meal plan can help to relieve symptoms associated with these illnesses.

In addition, you may need to supplement with some vitamins or minerals if you are having problems with absorption. These supplements should be recommended by your doctor. Your doctor may also opt to prescribe pancreatin, which is a medication that can be used to substitute any missing digestive enzymes. This medication promotes better digestion and absorption of nutrients, which can help with diarrhea.

7. Cystic fibrosis

Some genetic illnesses can also cause abnormalities to tissues in the intestinal tract. Cystic fibrosis, for example, affects the production of secretions in various organs, and mainly affects the lungs and intestines. Secretions are often thicker and drier, leading to alternating periods of diarrhea and constipation.

In addition, you may experience other symptoms like shortness of breath, persistent coughing, frequent lung infections, fatty stools with a foul odor, indigestion, weight loss and more.

What to do: Generally, genetic illnesses are detected at birth through a blood test, however they may be detected through other genetic tests that look for genetic mutations.

Treatment for cystic fibrosis usually involves prescription medications, respiratory physio and monitoring by a registered dietitian. Treatment is aimed at improving quality of life.

8. Bowel cancer

Bowel cancer can cause symptoms like frequent diarrhea, weight loss, fatigue, and bloody stools. Symptoms will vary depending on the location of the cancer and its staging.

What to do: If you experience these symptoms for longer than 1 month, and are over the age of 50 or have a family history of bowel cancer, you should see your doctor. The doctor will evaluate your symptoms and order testing, like a colonoscopy, CT scan and stool testing. Treatment should be started promptly for best outcomes.

Treatment options

To treat chronic diarrhea, the doctor will first focus on preventing dehydration or malnutrition. He or she may provide you with recommendations for daily fluids and food intake.

The treatment of the diarrhea will depend on the underlying cause. For example, the doctor may prescribe antibiotics to treat an intestinal infection, anti-inflammatories for auto-immune diseases, or remove medications that are causing diarrhea as a side effect.

What to eat

If you have chronic diarrhea, you should see a registered dietitian not only to formulate an eating plan, but also to assess the need for additional nutritional supplements. Supplements, like vitamins and minerals, can help to maintain or recuperate any weight loss.

You should choose foods that are easy to digest and absorbs, like:

Soups or purees made with boiled vegetables that do not stimulate the intestines. Great choices include pumpkin, carrots, squash, potatoes or sweet potatoes.
Underripe bananas, or cooked fruit (e.g. apples, peaches or pears)
Oatmeal
Cooked rice
Boiled or grilled white meat, like chicken or turkey
Boiled or grilled fish

You should also aim to drink 2 L of fluids per day (e.g. water, tea, coconut water or strained fruit juices). You can also drink electrolyte solutions, which you can purchase the pharmacy. These electrolytes should be consumed after each episode of diarrhea to prevent dehydration and loss of minerals. See what to eat with diarrhea and what you should avoid.