Diarrhoea usually occurs when fluid cannot be absorbed from the contents of   bowel or when extra fluid is secreted into   bowel causing watery faeces.
Short-term diarrhoea :  Diarrhoea is usually a symptom of gastroenteritis (a bowel infection). It can be caused by:
A virus, such as a Norovirus or Rotavirus A Parasite , such as the Giardia intestinalis,   that causes Giardiasis Bacteria, such as Campylobacter, Clostridium difficile (C. difficile), Escherichia coli (E. coli), Salmonella and Shigella: they all may cause food poisoningOther causes of short-term diarrhoea include:
Emotional upset or anxiety Intake of too much coffee or alcohol Any food allergy Appendicitis (painful swelling of the appendix) Damage to the lining of the intestines due to radiotherapy. Diarrhoea can also sometimes be a side effect of medicineslike :
Antibiotics Antacid medicines that contain magnesium Some medicines that are used in chemotherapy Non-steroidal anti-inflammatory drugs(NSAIDs) Selective serotonin reuptake inhibitors (SSRIs) Statins - cholesterol-lowering medicines Laxatives - medicine used to help empty   bowels, if   constipated Long-term diarrhoea
Bowel cancer - which can cause diarrhoea and blood in   stools Chronic pancreatitis - inflammation of the pancreas, a small organ that produces hormones and digestive juices Coeliac disease - a gastrointestinal tract disorder   where one is intolerant to the protein gluten Crohn's disease - a condition that causes inflammation of the gastrointestinal tract Irritable bowel syndrome (IBS) - a poorly understood condition where the normal functions of the bowel are disrupted Microscopic colitis - a type of inflammatory bowel disease that causes watery diarrhoea Ulcerative colitis - a condition that affects the colon (large intestine) Cystic fibrosis - an inherited condition that affects the lungs and digestive system Persistent diarrhea can also sometimes occur following a gastrectomy. This is a surgical operation to remove part of the stomach - for example, as a treatment for stomach cancer.

Diarrhea is associated with symptoms depending on the cause and who is affected.
Symptoms include:-
Watery stools Abdominal cramps Thin or loose stools Sense of urgency to have a bowel movement Nausea and vomiting
In addition to the symptoms described above, the symptoms of complicated diarrhoea include:-
Persitent diarrhoea can lead to dehydration Blood, mucus, or undigested food in the stool Weight loss

Drink fluids : It is important to drink plenty of fluids to avoid dehydration.
Oral Rehydration Solution  (ORS) : ORS should be used to prevent dehydration. Standard home solutions such as salted rice water, salted yoghurt drinks, vegetable and chicken soups with salt can be given. 
Medications: Antibiotics are beneficial in certain types of acute diarrhoea, they are usually not used except in specific situations. Over the counter drug    Pepto-Bismol ( Bismuth subsalicylate ) , or anti-motility drug Imodium plus (    Loperamide hydrochloride with simethicone ) are few of medicines for diarrhoea.

To prevent the spread of infections that cause diarrhoea, always maintain high standards of hygiene. For example:-
Wash hands thoroughly before eating or preparing food and after going to the toilet. To get toilet clean, including the handle and the seat, with disinfectant after each bout of diarrhoea. Avoid sharing towels, cutlery or utensils with other household members.

The following diarrhoeal conditions should be further investigated:-
In infants Moderate or severe diarrhoea in young children Associated with blood Associated non-cramping abdominal pain, fever, weight loss, etc. In travellers In food handlers, because of the potential to infect others; In institutions such as hospitals, child care centers, or geriatric and convalescent homes. Stool sample: To know the cause of the infection
Blood test: Blood test is generally done to test the signs of inflammation which may suggest disease like inflammatory bowel disease If the cause of diarrhoea is still not clear, then patient may be advised for further investigations. Like:
Sigmoidoscopy - Where an instrument called a Sigmoidoscope (a thin, flexible tube with a small camera and light on one end) is inserted into rectum and up into sigmoid colon, S-shaped last part of the colon.

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