Diarrhea is defined as loose stools occurring three or more times in a day. Chronic diarrhea is diarrhea that is persistent or lasts from two to four weeks.
There are many possible causes of diarrhea, such as:
- Eating certain foods
- Viral infections
- Bacterial infections
- Campylobacter
- Escherichia coli (E. coli)
- Salmonella
- Shigella
- Parasitic infections
- Cryptosporidium enteritis
- Entamoeba histolytica
- Giardia lamblia
- Digestive problems and diseases
- Celiac disease
- Irritable bowel syndrome (IBS) and other functional gastrointestinal (GI) disorders
- Inflammatory bowel disease (IBD)
- Crohn’s disease
- Ulcerative colitis
- Small intestinal bacterial overgrowth (SIBO)
- Some medications
- Antibiotics
- Antacids containing magnesium
- Cancer medications
- Long-term use of medications
- Laxative use
- Caffeine intake
- Alcohol use
- Food allergies and intolerances
- Complications due to past abdominal surgeries
What Are Symptoms of Diarrhea?
Diarrhea is a symptom of many different conditions. Signs of diarrhea may include:
- Urgent need to use the bathroom
- Loss of control of bowel movements
- Abdominal cramps/pain
Symptoms that may accompany diarrhea include:
- Nausea
- Fever
- Chills
- Loss of appetite
- Dehydration
- Vomiting
- Bloating
- Fatigue
- Bloody stools
- Lightheadedness
- Dizziness
Diarrhea may cause:
- Dehydration
- Thirst
- Urinating less than usual
- Dark-colored urine
- Dry mouth
- Tiredness
- Decreased skin turgor
- Lightheadedness or fainting
- Sunken eyes or cheeks
- Malabsorption
- Bloating
- Gas
- Changes in appetite
- Loose, greasy, foul-smelling bowel movements
- Weight loss
What Is the Treatment for Diarrhea?
Dietary changes may help treat diarrhea. Foods that can help stop diarrhea are those that are easy-to-digest and binding, such as:
- Pasta
- Rice
- Crackers
- Bananas
- Potatoes
- Oatmeal
Other home remedies for diarrhea include:
- Drink plenty of fluids
- Consume soups
- Eat salty foods to help prevent dehydration
- Increase fiber intake
- Take over-the-counter (OTC) anti-diarrheal medicines
- Take probiotics
- Avoid food and drinks that are triggers such as milk or eggs
Treatment for diarrhea depends on the cause. Dietary changes and home remedies are usually adequate and diarrhea will go away on its own with rest, hydration, and a bland diet. When medical treatment is needed it may include:
- Intravenous (IV) fluids to treat and prevent dehydration
- Anti-diarrheal medications
- Loperamide (Imodium)
- Diphenoxylate-atropine (Lomotil)
- Bismuth subsalicylate (Pepto-Bismol, Kaopectate)
- Antibiotics, if diarrhea is caused by certain bacterial infections
- Treating any underlying medical condition
- Stopping or changing medications
- Do not stop or change any medications without first talking to your doctor
From 
https://iffgd.org/lower-gi-disorders/diarrhea/common-causes.htm
https://www.uptodate.com/contents/diarrhea-in-adolescents-and-adults-the-basics?search=diarrhea&source=search_result&selectedTitle=4~150&usage_type=default&display_rank=4
https://kidshealth.org/en/parents/diarrhea.html
https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/symptoms-causes