What Causes Diarrhea? (Top 10 Reasons & What to Do)

What is it:

Diarrhea is caused by conditions in which the intestines are unable to absorb or eliminate water as normal, such as stress, anxiety, food poisoning, inadequate absorption of food, inflammatory intestinal disease or even with some medication use. 

Diarrhea is characterized by increased intestinal activity that results in a higher number of bowel movements. Stool can appear softer, but it is generally more liquid. 

Normally, diarrhea in itself is not a serious finding, but it should be assessed by your doctor if it persists for longer than 2 to 3 days, as you may experience dehydration as a result. Symptoms that may accompany diarrhea include excessive fatigue, decrease urine production, dizziness, or confusion. Therefore, if you are experiencing diarrhea, you should maintain adequate fluid intake to promote recovery and prevent complications. 

Why do i have diarrhea?

The main causes of diarrhea are:

1. Food poisoning

Food poisoning is one of the most frequent causes of diarrhea. It occurs after consuming food or water that is contaminated with bacteria or viruses and results in mild diarrhea. This type of stool may contain blood or mucus, and can be accompanied by other symptoms like fever, intestinal cramping, nausea or vomiting. 

Generally, poisoning happens when food is not properly prepared (especially meat), touching food with dirty hands or eating expired food. 

What to do: You should keep the body hydrated by drinking plenty of water and electrolyte solutions, resting, and eating small, light meals like toast, banana or rice. Read more about home remedies for food poisoning that you can implement at home. 

In the meantime, if the diarrhea does not improve after 2 or 3 days or if you start to have symptoms of dehydration (like confusion or palpitations), you should seek medical attention. Populations like children and older adults should also be assessed if they experience these symptoms. The doctor may prescribe food poisoning medications to help to speed-up recovery and reduce symptoms. 

2. Irritating foods

Some foods, like acid fruit, fried food, cheese, ice cream, onion, garlic or products with caffeine (like coffee, green tea or chocolate), can irritate the intestines if consumed in large quantities. These foods can cause diarrhea, cramping or excess gas. Learn more about food that causes more gas. 

What to do: You should avoid or reduce your consumption of food that irritates the intestines. You should increase your fluid intake to maintain your hydration status. Ensure you incorporate lighter foods that are easier to digest into your diet, like pear, guava, apple, mashed potato or mashed pumpkin, for example. 

3. Naturally laxative food

Some types of food, especially greens, fruit and seeds, are rich in fiber and therefore contain laxative properties that stimulate intestinal functioning. This results in softer stools. Check out a list of fruits that are natural laxatives.

People who over-eat this type of food can experience diarrhea for 1 to 2 days.

What to do: You should avoid the excessive consumption of this food, especially when you already have diarrhea. It is important to increase your water intake and eat light meals that are easy to digest. 

4. Stress and anxiety

Stress and anxiety can trigger the chemical signals in the brain to release hormones like adrenaline and cortisol. This release can increase a person’s mental awareness as well as change the way food is digesting. These hormones can increase intestinal muscle contractions, and therefore, it is common to experience diarrhea, abdominal pain or nausea in moments of stress and anxiety. 

What to do: You should practice habits to relieve stress and anxiety, like relaxing in a calming environment or drinking a calm tea, like chamomile, passiflora or valerian. To prevent it in the future, you should regularly engage in activities you like, such as walking, or taking up a hobby. You can also explore seeking medical assessment or psychotherapy if diarrhea occurs frequently. 

5. Intestinal parasites

Intestinal parasites, like pinworms, roundworms or tapeworm, are parasites that lodge into the intestine. They alter the digestion and absorption of food and cause symptoms like constant diarrhea, abdominal pain, bloody stools, nausea, loss of appetite or nausea. Read more about the symptoms of intestinal infections and how they can present. 

These worms are generally transmitted through water or food like vegetables, fruits, and raw/uncooked fish or meat which has been contaminated with parasite eggs. Infections can also be transmitted when handling food with unwashed hands. 

What to do: If you suspect a parasitic infection, you should see your doctor to initiate treatment. Medications may include antiparasitics, like albendazole or mebendazole. It is also to adopt adequate hygiene habits, like washing your hands, washing fruits and vegetables when handling, and cooking fish and meat adequately. These considerations can prevent your risk for a parasitic infection in the future.

6. Food intolerance

Food intolerance is characterized by difficulty digesting certain foods, like milk, bread, pasta or food additives (like dyes and preservatives). You will usually experience symptoms within a few hours of its consumption, like excess intestinal gas, nausea or abdominal cramps. 

Although symptoms can present similarly, a food intolerance is different from a food allergy. Food allergies have an additional immune response and can cause symptoms like difficulty breathing, chest pain, and a swollen through or face. 

If you suspect you may have a gluten intolerance, report your symptoms in our online quiz to determine your risk for this condition.

What to do: Generally, diarrhea caused by food intolerances improves within 24 hours. You should maintain adequate hydration by regularly sipping water and electrolyte solutions. It is also important to identify the food that caused the intolerance and follow-up with your doctor to confirm an intolerance diagnosis. You may need to follow a certain diet and read food labels to avoid future bouts of diarrhea. 

7. Inflammatory bowel diseases

Some intestinal diseases, like ulcerative colitis, Crohn’s disease and celiac disease can trigger inflammation in the intestines from chronic diarrhea that lasts for over 4 weeks. Generally, they are accompanied by symptoms live fever, abdominal pain or stool with blood or mucus. Many times, inflammatory bowel diseases can cause periods of constipation that alternate with diarrhea. 

What to do: You should see your doctor for diagnosis so that appropriate treatment can be initiated. It may involve the use of anti-inflammatories, steroids, antibiotics, antidepressants or anti-diarrhea medication. In addition, you should see a registered dietitian to develop a customized diet plan for your intestinal disease. 

8. Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a condition that is characterized by changes to bowel movements that are triggered by intolerances to certain food, like citric fruit, coffee beans or fizzy drinks. It can also be triggered by anxiety or stress and result in diarrhea flare-ups, which can be accompanied by abdominal cramping and excess gas. 

In some cases, you may also experience bloody diarrhea or periods of constipation that alternate with diarrhea. 

What to do: You should avoid consuming foods that may cause your diarrhea flare-ups and identify whether certain situations are triggering stress or anxiety. You can try partaking in relaxing activities, or drink a soothing tea like chamomile or valerian tea. You should see your doctor if the diarrhea does not approve and consider being monitored by a therapist if you diarrhea is related to anxiety. Learn about the IBS diet that your doctor or a registered dietitian may recommend to help manage symptoms.

9. Medication use

Some medications, like antibiotics, anti-inflammatories, antihypertensives, or antacids are known to have diarrhea as a side effect. They can change intestinal flow or stimulate changes to intestinal flora growth. This can also happen when receiving chemotherapy medication. 

What to do: You should communicate this side effect to your prescriber so that an alternative treatment may be considered. The doctor may reduce the dose, swap it for another medication, or additionally prescribe an anti-diarrhea medication.  

You should not stop your medication abruptly without consulting with your prescriber first. If taking antibiotics, you can consider additionally taking probiotics. You should also avoid excessively using laxatives. 

10. Gastrointestinal surgery

Some gastrointestinal surgery, like bariatric surgery, gallbladder removal or intestinal resections can change the flow of absorption of water and fat, resulting in diarrhea. This is a normal, expected finding and usually occurs in the first month after surgery. You may also experience excess gas and nausea. 

What to do: You should maintain adequate hydration by drinking water or other fluids as recommended by your doctor. Ensure you attend all follow-ups and, depending on your surgery, you should follow an individualized diet as advised by a registered dietitian. Following bariatric surgery, for example, the doctor or dietitian may advice a bariatric diet, which is made-up of 3 phases.