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Oral Rehydration Therapy

ORS - Oral Rehydration Salts : The most effective, least expensive way to manage diarrhoeal dehydration.

"The discovery that sodium transport and glucose transport are coupled in the small intestine so that glucose accelerates absorption of solute and water (is) potentially the most important medical advance this century."

British Scientific Journal
5th August, 1978

Percentage of children with diarrhoea in the past 2 weeks who received ORT (1990-2000)

ORT is the giving of fluid by mouth to prevent and/or correct the dehydration that is a result of diarrhoea. As soon as diarrhoea begins, treatment using home remedies to prevent dehydration must be started. If adults or children have not been given extra drinks, or if in spite of this dehydration does occur, they must be treated with a special drink made with oral rehydration salts (ORS).

The formula for ORS recommended by WHO and UNICEF contains:

Reduced osmolarity ORS


Reduced osmolarity ORS


Sodium chloride




Glucose, anhydrous




Potassium chloride


Glucose, anhydrous


Trisodium citrate, dihydrate






Total Osmolarity


Magic Bullet: The History of Oral Rehydration TherapyOral Rehydration Therapy - A Brazilian Experiencepdf 39 pages 7.4 mb.
by Joshua Nalibow Ruxin


Med Hist. 1994 October; 38(4): 363–397.
PMCID: PMC1036912

The Oral Rehydration Therapy

The Canadian Journal of Paediatrics 1994; 1(5): 160-164

Oral rehydration therapy with an inexpensive glucose and electrolyte solution as promoted by the World Health Organization has reduced substantially the number of deaths from dehydration due to diarrhea. In addition, recent research suggests that these solutions have advantages over conventional therapy. Yet, oral rehydration therapy has not been used extensively in developed countries.

Acute gastroenteritis is one of the most common illnesses affecting infants and children in Canada and the world. The average child under age 5 experiences 2.2 diarrheal episodes per year.1 Treatment from resulting dehydration accounts for an estimated 200,000 hospitalizations per year in the U.S.2 with comparable rates occurring in Canada. Worldwide as many as 4,000,000 children per year die as a result of gastroenteritis and resulting malnutrition. Prolonged diarrhea and malnutrition are a primary cause of morbidity and mortality in Canadian native populations.

Oral rehydration therapy (ORT), using a simple, inexpensive, glucose and electrolyte solution promoted by the World Health Organization (WHO) has reduced the number of deaths from dehydration due to diarrhea by about a million per year.1,3 In spite of its efficacy, ORT has not been used extensively in developed countries. Recent research, summarized in this report, suggests that the use of oral rehydration solutions have advantages over conventional therapy. In an effort to encourage the use of ORT, a simple approach to rehydration is outlined.

Oral rehydration takes advantage of glucose-coupled sodium transport,4 a process for sodium absorption which remains relatively intact in infective diarrheas due to viruses or to enteropathogenic bacteria, whether invasive or enterotoxigenic. Glucose enhances sodium, and secondarily, water transport across the mucosa of the upper intestine.5 For optimal absorption, the composition of the rehydration solution is critical. The amount of fluid absorbed depends on three factors: the concentration of sodium, the concentration of glucose and the osmolarity of the luminal fluid. Maximal water uptake occurs with a sodium concentration from 40 to 90 mmol/L, a glucose concentration from 110 to 140 mmol/L (2.0 to 2.5 g/100 mL) and an osmolarity of about 290 mOsm/L, the osmolarity of body fluids.6 Increasing the sodium beyond 90 mmol/L may result in hypernatremia; increasing the glucose concentration beyond 200 mOsm/L, by increasing the osmolarity of the solution, may result in a net loss of water. CHO to Na ratio should not exceed 2:1 in these solutions.

For practical purposes in Canada, rehydration can be accomplished using solutions with higher sodium, i.e., 75-90 mmol/L. These are termed rehydration solutions (ORS). Prophylaxis of dehydration and maintenance involve solutions with 45-60 mmol/L of sodium. These are termed maintenance solutions. High sodium rehydrating solutions used to treat acute dehydration may be used for maintenance by giving the solution alternately on a 1-to-1 basis with a no-sodium or low-sodium fluid such as water, low CHO fluids, or breast milk. The high sodium ORS should not be used as the sole fluid intake for maintenance of hydration. Fruit juices and pop are not efficacious because of their high carbohydrate concentration, osmolarity and the inadequate sodium concentration.7 Individualized dietary management of the patient during acute diarrhea is the key and should be emphasized.

Oral rehydration and maintenance solutions presently in use, although effective in rehydration, do not decrease stool volume because of the relatively high osmolarity of the glucose which they contain. The challenge, therefore, is to provide adequate glucose to the sodium pump without increasing the osmolarity of the rehydration solution.

This has been done successfully by substituting short chain glucose polymers (starch) from rice and other cereals for glucose in the oral rehydration mixture.8 In field trials in developing countries,8,9 ORS containing glucose polymers, primarily from rice and corn, were found not only to be as effective in correcting dehydration as glucose-based ORS, but also to offer the additional advantage of reducing the amount and duration of diarrhea by 30%, thereby reducing morbidity and costs of treatment and increasing acceptability. The effectiveness in diarrhea typical of North America may be less marked, i.e., reducing stool output by 18%.

Defined short-chained glucose polymers from rice may also be safe and effective in the treatment of acute diarrhea.10 Wapnir et al11 found that a solution containing 30 g/L of rice syrup solids (180 mOsm/L) resulted in 40% more water absorption than a similar solution which contained 20 g/L of glucose (230 mOsm/L). A clinical study with solutions containing rice-syrup solids confirmed their efficacy in the rehydration of infants with acute diarrhea. Further, such solutions decreased stool output, and promoted greater absorption and retention of fluid and electrolytes than did a glucose-based solution.12

Amino acids have also been suggested as additives to ORS. The addition of alanine alone to the WHO oral rehydration solution (ORS) was not found to give additional benefits.13 However, Khin-Maung-U and Greenough8 found that alanine, added to a glucose polymer-based ORS, decreased the amounts of stool by a further 10% to 40%. Nevertheless, these are not currently recommended by WHO. Rice-based corn and lentil-based oral rehydration solutions have been extensively tested and may eventually be made available.

Along with improved oral rehydration solutions have come advances in the field of early refeeding. Fasting has been shown to prolong diarrhea. This may be due to undernutrition of the bowel mucosa which delays the replacement of mucosal cells destroyed by the infection. Although there is general agreement that breast-feeding should continue in spite of diarrhea,14 early refeeding with a lactose-containing formula is usually well tolerated.15 Early refeeding should commence 6-12 hours into therapy.

On the basis of these findings and recent recommendations, 16 the following principles should be followed in treating diarrheal disease:

Fluid therapy should include the following three elements: rehydration, replacement of ongoing losses, and maintenance.
Fluid therapy is based on an assessment of the degree of dehydration present. Principles are as follows:
No dehydration - If diarrhea is present, but urinary output is normal, the normal diet and breast-feeding may continue at home with fluid intake dictated by thirst. High osmolarity fluids such as undiluted juices should be avoided, and maintenance oral electrolyte solution (Na 45-60 mmol/L) offered "ad libitum."

Mild - If symptoms and signs are limited to decreased urinary output and increased thirst, mild dehydration is suspected. Assessment and treatment under close supervision are indicated. Rehydration consists of ORS or maintenance solution 10 mL/kg/hr with reassessment at 4-hour intervals. Breast-feeding continues. Early refeeding with the child's customary formula at the usual concentration is recommended. Extra ORS or maintenance solution (e.g., 5-10 mL/kg) may be given after each stool if diarrhea persists.

Moderate - If at least two of the following signs, sunken eyes, loss of skin turgor ("tenting" of abdominal skin lasting less than 2 seconds), or dry buccal mucous membranes are present, moderate dehydration is diagnosed and rehydration consisting of ORS 15-20 mL/kg/hr with direct observation and reassessment at 4-hour intervals. If dehydration is corrected, therapy for ongoing losses and maintenance are continued as outlined above. If not, treatment is repeated as indicated by clinical signs or symptoms.

Severe - If, in addition to signs of moderate dehydration, there is rapid breathing, lethargy, coma, a rapid thready pulse or "tenting" of the skin lasting more than 2 seconds, severe dehydration and shock are present. Blood pressure should be measured. Prompt intravenous therapy is indicated with rapid infusion of saline plasma or colloid sufficient to replete blood volume (10-20 mL/kg over 30 minutes may be necessary). Intraosseous infusion should be used if an intravenous line cannot quickly be inserted.

General comments. Vomiting is not a contraindication to ORT. ORS should be given slowly but steadily to minimize vomiting. Fluids may be administered by nasogastric tube if required. The child's clinical condition should be frequently assessed. A child should never be kept on ORS fluid alone for more than 24 hours. Early refeeding should begin within 6 hours. A full diet should be reinstituted within 24 to 48 hours, if possible.

There are certain contraindications to the use of ORT:

  • Protracted vomiting despite small, frequent feedings

  • Worsening diarrhea and an inability to keep up with losses

  • Stupor or coma

  • Intestinal ileus.

As ORS can be administered easily by a properly instructed parent, and because dehydration can be corrected quickly, it lends itself well for use in an outpatient department or nursing station. At the end of 4 hours, the child can either be sent home on maintenance therapy or, if dehydration persists, be observed for further therapy. Intelligent use of ORT can decrease hospital admissions, an important consideration in a time of decreasing hospital budgets. Although in our society intravenous therapy is often considered more convenient than ORT, clinicians should feel more comfortable as they become more accustomed to the use of ORT.

TABLE 3: Simplified ORT protocol in mild to moderate rehydration

mild moderate
1st hour 20 mL/kg/hr 20 mL/kg/hr
next 6-8 hours 10 mL/kg/hr 15-20 mL/kg/hr
Reassessment at 4-hour intervals

There are many different equations for calculating administration rates in oral rehydration. ORT may be given in amounts equal to fluids calculated for intravenous administration. Alternately, fluids may be delivered by nasogastric tube


  • Dehydration accompanying infantile gastroenteritis should be treated with early oral rehydration and early refeeding strategies.

  • Infants with gastroenteritis should be offered maintenance solution to prevent dehydration. Parents and daycare centres should keep maintenance solution on hand in anticipation of episodes of infectious diarrhea.

  • ORS and maintenance solutions and instructions in their use should be made available at reasonable costs.

  • Medical facilities should have ORT protocols available for staff and patients.

  • Antidiarrheal drugs, antibiotics and antiemetic therapy are rarely indicated in gastroenteritis in childhood and should be discouraged.

  • Home-made oral rehydration solutions are discouraged since serious errors in formulation have occurred.

  • Infants with mild to moderate dehydration should be treated under medical supervision with ORT in preference to intravenous rehydration.

  • Infants with severe dehydration should initially be treated with intravenous or intraosseous rehydration.

  • Breast-fed infants with dehydration should be given ORT in conjunction with continued breastfeeding.

  • Early refeeding should commence as soon as vomiting has resolved, approximately 6-12 hours.

  • Non-lactose containing formulae or milks may be used if diarrhea and abdominal cramps persist beyond expected 5- to 7-day course suggesting clinical lactose intolerance.

  • Further initiatives to encourage ORT use by patients and professionals should be developed.

Oral Rehydration Therapy (ORT)

From Wikipedia, the free encyclopedia Oral rehydration therapy, (also called ORT, oral rehydration salts or solutions (ORS), or oral electrolyte), is a simple, cheap, and effective treatment for diarrhea-related dehydration, caused by e.g. cholera. It consists of a solution of salts and other substances such as glucose, sucrose, citrates or molasses, which is administered orally. It is used around the world, but is most important in the Third World, where it saves millions of children from diarrhea—still their leading cause of death. History ORT was developed in the late 1960s by researchers in India and International Centre for Diarrhoeal Disease Research in Bangladesh (then East Pakistan), for the treatment of cholera. The Indo-Pakistani War of 1971 provoked a public health emergency in the refugee camps set up to house those fleeing the violence. With cholera spreading rapidly and death rates rising, the head of a medical centre in one of the camps instructed his staff to distribute Oral Rehydration Salts (ORS). In the refugee camps where ORS was being used the death rate was only 3%, compared to 20–30% in those camps using only intravenous fluid therapy.[citation needed] In 2002, Drs. Norbert Hirschhorn, Dilip Mahalanabis, David R. Nalin, and Nathaniel F. Pierce were awarded the first Pollin Prize for Pediatric Research, in recognition of their work in developing ORT. Between 1980 and 2000, ORT decreased the number of children under five dying of diarrhea from 4.6 million worldwide to 1.8 million—a 60% reduction. According to The Lancet (1978), ORT is "potentially the most important medical discovery of the 20th century". Today, the total production is around 500 million ORS sachets per year, with the children's rights agency UNICEF distributing them to children in around 60 developing countries. ORS represents a cheap and effective way of reducing the millions of deaths caused each year by diarrhea. Physiology Oral rehydration therapy is widely considered to be the best method for combating the dehydration caused by diarrhea and/or vomiting. Various diseases cause damage to the intestine, allowing water to flow from the blood into the intestine, depleting the body of both fluid and electrolytes. This may be

In the human body, water is absorbed and secreted passively; it follows the movement of salts, based on a principle called osmosis. So, in many cases, diarrhea is caused by intestine cells secreting salts (primarily sodium) and water following passively along. Simply drinking water is ineffective for 2 reasons: (1) the large intestine is usually secreting instead of absorbing water, and (2) electrolyte losses also need compensating. As such, the standard treatment is to restore fluids intravenously with water and salts. This requires trained personnel and materials which are not sufficiently available in the Third World. However, it was discovered that the body can absorb a simple solution containing both sugar and salt. The dry ingredients can be mixed and packaged, and then the solution can be prepared and delivered by people with minimal training. One diarrhea mechanism (like in cholera, which is a very dangerous form of profuse diarrhea), is an enterotoxin interfering with enterocyte cAMP and G-proteins. However, water can still be absorbed by cAMP-indepentent mechanisms, like the SGLT-transporter (sodium and glucose transporter, of which 2 types exist). This is achieved by combining salts and glucose. Oral rehydration can be accomplished by drinking frequent small amounts of an oral rehydration salt solution. It is important to rehydrate with solutions that contain electrolytes, especially sodium and potassium, so that electrolyte disturbances may be avoided. Sugar is important to improve absorption of electrolytes and water, but if too much is present in ORS solutions, diarrhea can be worsened. Oral rehydration does not stop diarrhea, but keeps the body hydrated and healthy until the diarrhea passes. Recipe There are several commercially available products but an inexpensive home-made solution consists of 8 level teaspoons of sugar and 1 level teaspoon of table salt mixed in 1 liter of water. A half cup of orange juice or half of a mashed banana can be added to each liter both to add potassium and to improve taste. If commercial solutions are used, true rehydration solutions should be used and sports drinks should be avoided (especially in younger children) as these solutions contain too much sugar and not enough electrolytes. One standard remedy is the WHO/UNICEF glucose-based Oral Rehydration Salts (ORS) solution. WHO/UNICEF ORS solution contains

Reduced osmolarity ORS grams/litre Reduced osmolarity ORS mmol/litre
Sodium chloride 2.6 Sodium 75
Anhydrous Glucose 13.5 Anhydrous Glucose 75
Potassium chloride 1.5 Chloride 65
Trisodium citrate, dihydrate 2.9 Potassium 20
Citrate 10
Total Osmolarity 245

In the human body, the plasma osmolality is about 285 mOsm/l.

An inexpensive home-made solution consists of

A half cup of orange juice or half of a mashed banana can be added to each liter to add potassium and improve taste.

If commercial solutions are used, true rehydration solutions should be used and sports drinks should be avoided (especially in younger children) as these solutions contain too much sugar and not enough electrolytes.

The amount of rehydration that is needed depends on the size of the individual and the degree of dehydration. Rehydration is generally adequate when the person no longer feels thirsty and has a normal urine output. A rough guide to the amount of ORS solution needed in the first 4-6 hours of treatment for a mildly dehydrated person is:

  • Up to 5 kg (11 lb): 200 – 400 ml
  • 5-10 kg (11-22 lb): 400 – 600 ml
  • 10-15 kg (22-33 lb): 600 – 800 ml
  • 15-20 kg (33–44 lb): 800 – 1000 ml
  • 20-30 kg (44-66 lb: 1000 – 1500 ml
  • 30-40 kg (66-88 lb): 1500 – 2000 ml
  • 40 plus kg (88 lb): 2000-4000 ml

Technique Adults and children with dehydration who are not vomiting can be allowed to drink these solutions in addition to their normal diet. People who are vomiting should be fed small frequent amounts of ORS solution until dehydration is resolved. Once they are rehydrated, they may resume eating normal foods when nausea passes. Vomiting itself does not mean that oral rehydration cannot be given. As long as more fluid enters than exits, rehydration will be accomplished. It is only when the volume of fluid and electrolyte loss in vomit and stool exceeds what is taken in that dehydration will continue. When vomiting occurs, rest the stomach for ten minutes and then offer small amounts of ORS solution. Start with a teaspoonful every five minutes in children and a tablespoonful every five minutes in older children and adults. If output exceeds intake or signs of moderate to severe dehydration occur, medical assistance should be sought.

On-line Resources

Oral Rehydration Therapy - A Brazilian Experience Oral Rehydration Therapy - A Brazilian Experiencepdf

updated: 23 August, 2019