What is Diarrhea?

The term diarrhea (also spelled diarrhoea) refers to passage of loose, watery stools. The usual frequency of passing loose stools or watery stools in cases of diarrhea is at least three or more times a day.

Acute and chronic diarrhea

Acute diarrhea lasts a day or two and usually resolves on its own. Diarrhea lasting more than 2 days may indicate a deeper pathology.

Chronic diarrhea indicates presence of diarrhea for at least 4 weeks. This usually indicates a systemic disease.

Chronic diarrhea may again be continued without relenting or may come and go with periods of normal stools and periods of diarrhea.

Problems with diarrhea

Diarrhea due to any cause or for any duration may cause dehydration. This means that the body loses fluid and electrolytes with numerous episodes of loose watery stools.

Normally most of the water that comes into the intestines is absorbed right back to give the solid or semi solid consistency of the stools.

When there are loose stools there is an inability of the intestines to absorb the water as well as the electrolytes (like salts including sodium, potassium, and chloride) and these are lost in stools.

Loose stools contain more fluids and electrolytes and weigh more than solid stools.

Who does diarrhea affect?

Diarrhea can affect persons of all ages. However, the dehydration caused by severe diarrhea is something that can affect infants, children and the elderly more severely.

Severe dehydration in these extremes of ages may be life threatening if not corrected urgently.

In the United States every adult has at least 1 episode of diarrhea annually while young children have an average of two episodes of acute diarrhea in a year.

Causes of diarrhea

The causes of acute and chronic diarrhea are different. Acute diarrhea is caused by infections by bacteria, viruses or parasites while chronic diarrhea is usually related to a functional disorder such as irritable bowel syndrome or an intestinal disease such as Crohn’s disease.

Common organisms that may cause acute bacterial diarrhea include bacteria like Campylobacter, Salmonella, Shigella, and Escherichia coli (E. coli); viruses like rotavirus, norovirus, cytomegalovirus, herpes simplex virus etc. and parasites like Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.

Food intolerance, allergic reactions to certain medications, medication side effects etc. may also give rise to diarrhea.

Traveller’s diarrhea usually affects tourists and visitors to developing countries in Africa, Asia, Latin America, and the Caribbean. This is usually caused by eating food or drinking water contaminated with bacteria, viruses, or parasites.

Diagnosis of diarrhea

Diagnosis of diarrhea and its cause may be needed if it does not subside in a day or two.

Stool is examined in the laboratory for presence of causative organisms. Several laboratory and imaging studies may be used to diagnose more chronic causes of diarrhea.

Treating diarrhea

The first step to treating diarrhea is replenishing the lost fluids and electrolytes and correcting dehydration.

Although drinking plenty of water is important in preventing dehydration, water does not contain electrolytes. Fruit juices, caffeine-free soft drinks, sports drinks and broths may help adults prevent dehydration.

The choice of drink for children however is the oral rehydration solution prescribed by the World Health Organization (WHO). This replenishes both the water and electrolytes in adequate amounts.

Continuing a healthy and nutritious diet and breast feeding (in case of young breastfeeding children) helps recovery and prevents malnutrition due to prolonged diarrhea.

Diarrhea Treatment

In most cases of diarrhea the condition resolves on its own in a day or two. These types of diarrhea do not require assessment, diagnosis and treatment other than prevention of dehydration. The body’s immune system gears up to fight and remove the infection.

How long does diarrhea last?

In children diarrhea may take around 5 to 7 days to pass. In all the symptoms of diarrhea usually do not persist over two weeks.

When caused by rotavirus infection diarrhea may last for around three to eight days, with norovirus it is around two days and with bacterial infections like campylobacter and salmonella, diarrhea may last two to seven days.

Those infested with parasites like giardia may take several weeks to recover fully. In patients who suffer from periods of diarrhea lasting for over four weeks, it is termed chronic diarrhea.

Some of the measures adopted for treatment and prevention of complications include:-

Plenty of fluids should be taken

Diarrhea leads to increased loss of fluids and electrolytes like, Potassium and Calcium in the watery stools.

Normally gut absorbs these fluids and electrolytes while food passes through it. During an infection the gut fails to absorb the water or the infection and inflammation leads to copious secretion of water into the intestinal lumen. This leads to the water loss.

Excessive water and electrolyte loss may cause dehydration. One of the primary and most important treatment approaches to a case of diarrhea is to replenish the water and electrolytes. Babies and the elderly with diarrhea are most at risk of dehydration.

The person should be offered frequent sips of water and oral rehydration solution (ORS) prescribed by the World Health Organization.

ORS is available without a prescription and comes in sachets. These contain several salts and glucose. The contents of the sachet are dissolved in water and taken in small sips.

Children should be given an ORS each time they have an episode of diarrhoea. The exact amount of ORS they should drink will depend on their size and weight.

Even if the child or the person is vomiting, fluids may be offered by mouth. Fizzy drinks should be avoided as they may make the diarrhea worse.

If the child is breastfed or bottle fed, that should be continued.

In older children and adults healthy and nutritious food needs to be taken in small amounts to prevent malnutrition that may be seen after long episodes of diarrhea.

Fatty, spicy and heavy foods should be avoided. If there is vomiting and dehydration, fluids are given until the dehydration is corrected before introducing foods.

Intravenous fluids

When dehydration is severe, hospital admission may be required. In these cases intravenous fluids are given to replenish the lost water and electrolytes.

As soon as the patient is able to take fluids by mouth and vomiting stops, ORS may be started.


There are a few antidiarrheal medicines that may control diarrhea and shorten the duration by around a day. These are, however, not essential and are not prescribed normally.

Loperamide is one such agent. It shows the movement of the muscles in the intestines and thus prevents diarrhea.

Being in contact with the intestinal wall for a longer duration, the excess water is absorbed. This leads to formation of semisolid stools.

Antidiarrheals should not be taken if there is blood or mucus in stools or if there is high fever that indicates a more severe infection. Children should not be given antidiarrheal medicines at all. Pain and fever relievers like paracetamol may be used in cases of fever.

Antibiotics are another class of medications that may be given when the cause of diarrhea is diagnosed. If the cause is unknown, antibiotics are not recommended. This is because antibiotics can act only on bacteria and fail to help in viral diarrhea and also lead to side effects of their own.

Home treatment

  • Home treatment in a child with no dehydration includes:-
    • Plenty of fluids including ORS. In absence of OR,S food based home fluids like gruel, soup, unsalted or salted yoghurt drink, green coconut water, weak tea, unsweetened fresh fruit juice or rice water may be given. Fluids to be avoided include fizzy drinks, sweetened tea, sweetened fruit drinks or coffee.
    • Continuing feeding, breast or bottle feeding
    • Administering Zinc as supplemental tablets for 10 to 14 days.
    • Teaching the mother to be vigilant about the symptoms of dehydration in the child.
  • Home treatment in a child with some dehydration includes:-
    • ORS and extra fluids. ORS is given until the skin pinch test is normal and the child is calm and not thirsty. this usually takes four hours of rehydration
    • Continuing feeding, breast or bottle feeding
    • Administering Zinc as supplemental tablets for 10 to 14 days after rehydration is achieved
    • Teaching the mother to be vigilant about the symptoms of dehydration in the child and returning to the health center in cases of return of the symptoms
  • Treatment of a child with severe dehydration:-
    • Hospital admission is needed
    • Intravenous fluids are given to correct the dehydration rapidly
    • ORS should be given as soon as the child can take it even along with an IV drip
    • Zinc therapy is instituted once the dehydration is corrected

Diarrhea Symptoms

Diarrhea means passing loose and watery stools. The severity of the condition may vary between slightly watery faeces along with an upset stomach that stays for a day or two or extremely watery faeces along with severe abdominal pains.

Symptoms of diarrhea

Common symptoms associated with diarrhea include:-

  • Loose watery stools with three or more frequency a day
  • Change in consistency of stools from usual (stools may become loose or less formed)
  • Nausea and vomiting may be seen
  • High temperature or fever over 38ºC (100.4ºF)
  • Moderate to severe abdominal cramps
  • Headache
  • Loss of appetite. Babies and infants may refuse to feed
  • There may be a metallic or bitter taste in the mouth


With severe episodes of diarrhea there may be dehydration as well. This is particularly dangerous especially for young children and the elderly.

Babies having six or more episodes of Diarrhea in the past 24 hours are at risk of dehydration. Children with over six episodes of watery Diarrhea in the past 24 hours along with vomiting, bloody diarrhea and diarrhea that lasts for longer than two weeks are at risk of dehydration and need urgent attention.

Adults who have been recently treated in a hospital, or who have been treated with antibiotics, bloody diarrhea, persistent diarrhea and vomiting, abnormal weight loss and large volumes of watery diarrhea are at risk of dehydration and complications.

Symptoms of dehydration

Symptoms of dehydration include:-

  • In children:-
    • Increased thirst
    • Cold, pale and clammy skin
    • Irritable or drowsy
    • Passing urine infrequently and passing dark coloured urine
    • Cold hands and feet
    • Dry tongue
    • Sunken eyes and no tears
    • There are sunken cheeks and sunken soft spot over the skull
    • Skin stays pinched up and takes time to return to normal.
  • In adults:-
    • Increased thirst
    • Fatigue, dizziness and light headedness
    • Loss of appetite
    • Nausea
    • Dry tongue
    • Sunken eyes
    • Muscle cramps
    • Rapid heart rate

Diagnosis of diarrhea and dehydration

Diarrhea and dehydration is most commonly diagnosed clinically by symptoms.

Most cases resolve on their own within 2 days or less. In these cases diagnostic tests are usually not necessary.

If diarrhea lasts longer or is accompanied by symptoms such as fever or bloody stools diagnostic tests may be used to determine the cause of diarrhea.

Investigations and diagnosis involves:-

  • History of exposure to contaminated food or water or travel
  • Physical examination for dehydration symptoms
  • Stool is examined for bacteria, virus or parasites. Stool culture is also advised if the causative organism is not detected on examination
  • Blood tests are used to detect causes that may lead to chronic diarrhea. Routine blood tests may detect anemia in cases of parasitic or other infections. Infections also show up as raised white blood cell count.
  • Food allergy and intolerance tests may also be advised
  • Sigmoidoscopy or colonoscopy is advised if inflammatory bowel disease or bowel cancers are suspected. Sigmoidoscopy and colonoscopy involves introducing a thin, flexible, lighted tube with a camera on its tip into the large intestines.

Diarrhea Causes

Diarrhea is usually caused when the fluids within the intestines are not reabsorbed by the gut walls. This leads to loose, watery stools. Watery stools may also result from excessive water secretion from the intestines into the lumen or bowel.

Acute and chronic diarrhea

Diarrhea may be acute or chronic. Most cases of diarrhea begin suddenly and usually resolve on their own within a day or two.

Diarrhea lasting for more than two days may be problematic. Diarrhea is called chronic when it lasts for at least four weeks. This is usually due to some underlying functional or systemic disorder.

Causes of acute diarrhea

Diarrhea is a symptom of an underlying infection of the gastrointestinal tract rather than a disease in itself. Gastrointestinal infection may be caused by infections due to:-


Common bacteria that may cause diarrhea include Clostridium difficile (C. difficile), Escherichia coli (E. coli), Salmonella, Campylobacter and Shigella. These may all cause food poisoning and occur due to eating or consuming contaminated food or water. When gastroeneteritis occurs to travellers to developing countries in Africa, Asia, Latin America, and the Caribbean, it is termed Traveller’s diarrhea.


Several viruses may give rise to serious acute episodes of diarrhea. These include norovirus, rotavirus, herpes simplex virus, cytomegalovirus, hepatitis virus etc.

Parasites or intestinal worms

These agents are also notorious is causing diarrhea in children and in some adults. Some of the parasites that may cause diarrhea include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.

Other causes of short term acute diarrhea include:-

  • Emotional changes and anxiety may also give rise to short episodes of diarrhea
  • Food intolerance and allergies
  • Excessive alcohol consumption or excessive coffee
  • Appendicitis
  • After radiation therapy
  • Due to side effects of medications. Medications that are commonly implicated in causing diarrhea include antibiotics, magnesium containing antacids, non steroidal anti-inflammatory drugs (pain relievers), selective serotonin uptake inhibitors or SSRIs (used as antidepressants), cholesterol lowering agents like statins, purgatives that are used to empty the bowels, medicines used in cancer chemotherapy etc.
  • Damage to the intestines due to reduced blood supply as seen in hernias

Causes of chronic diarrhea

Chronic diarrhea usually lasts over 4 weeks and may be caused by an underlying gastrointestinal or systemic disease. Some of the causes include:-

  • Irritable bowel syndrome
  • Crohn’s disease
  • Coeliac disease
  • Diabetes - especially diabetic gastroparesis (a complication of long term diabetes)
  • Cystic fibrosis
  • Lactose intolerance or milk intolerance
  • Diverticular disease
  • After a gastrectomy operation
  • Chronic pancreatitis
  • Colitis and ulcerative colitis – Inflammatory bowel diseases including ulcerative colitis and Crohn’s disease may cause chronic bloody diarrhea or frequent presence of blood in the stools.
  • Cancer of the colon or rectum or presence of polyps
  • Ischemic or loss of blood supply to a part of the gut
  • Malabsorption syndromes may lead to chronic fatty or oily diarrhea. The stools are bulky, greasy or very bad smelling