Why the world's cheapest life-saver goes unused

Across 35 sub-Saharan African countries, only 43.6% of children under five with diarrhoea receive both oral rehydration salts (ORS) and zinc ¹⁰. The treatment is cheap and proven. A co-pack with enough ORS and zinc for one child's episode is listed by UNICEF at about USD 0.57 ³.

Diarrhoeal deaths in young children have fallen by roughly four-fifths since 1990, and oral rehydration is one of the reasons ². The 15-year evidence window brings together treatment refinements and delivery trials, including direct tests of affordability, zinc dosing and providers’ prescribing decisions.

The burden

WHO estimates that diarrhoea kills around 443,832 children under five each year, plus 50,851 children aged 5 to 9 ¹. It is the third leading cause of death in children aged 1-59 months ¹. There are nearly 1.7 billion episodes of childhood diarrhoeal disease every year ¹.

The Global Burden of Disease (GBD) 2021 study, run by the Institute for Health Metrics and Evaluation (IHME) and funded by the Gates Foundation, gives the long view ². Across all ages, diarrhoeal diseases caused an estimated 1.17 million deaths in 2021, down 60.3% from 2.93 million in 1990 ². The steepest fall was in children under five, where diarrhoeal deaths dropped 79.2% ². The GBD authors credit oral rehydration therapy, better water, sanitation and hygiene, and rotavirus vaccination ².

The burden that remains is still large. Of 59.0 million disability-adjusted life years (DALYs) lost to diarrhoea in 2021, 30.9 million were in children under five ². In young children, rotavirus caused an estimated 35.2% of diarrhoeal deaths, followed by Shigella (24.0%) and adenovirus (23.8%) ². Leading risk factors were low birthweight and short gestation in newborns, and child growth failure in older infants and toddlers ².

Deaths are concentrated where care is hardest to reach. A 2025 commentary from African public health researchers puts diarrhoea at 9% of all under-five deaths in sub-Saharan Africa ⁴. UNICEF's supply team, citing WHO, reported that 60% of child diarrhoea deaths occurred in ten countries: Bangladesh, the Democratic Republic of Congo, Ethiopia, India, Kenya, Niger, Nigeria, Pakistan, Tanzania and Uganda ³. That figure is older than the GBD estimates, but it shows how focused the problem is.

Diarrhoea and malnutrition feed each other. WHO describes diarrhoea as a leading cause of malnutrition in children under five, and each episode makes existing malnutrition worse ¹.

How it works

Diarrhoea is defined as three or more loose or liquid stools a day, or more often than is normal for the child ¹. The danger is not the stools themselves but what they carry out of the body. With each loose stool, and with vomit, sweat, urine and breath, a child loses water and electrolytes: sodium, chloride, potassium and bicarbonate ¹. A small child can become dangerously dehydrated quickly.

ORS replaces what is lost. ORS is a mixture of clean water, salt and sugar ¹. It is absorbed in the small intestine and replaces the water and electrolytes lost in stools ¹. It does not stop the diarrhoea. It keeps the child alive while the illness runs its course. That is one reason families and providers sometimes undervalue it: it is not seen as a cure ³.

The formula was changed to work better. Until the early 2000s, standard ORS had a total osmolarity of 311 mmol/L ⁵. Concerns about sodium levels led to a low-osmolarity formula of 245 mmol/L or less ⁵. WHO and UNICEF recommended the switch in 2005, together with zinc ³. Today's WHO ORS contains 75 mEq/L of sodium and 75 mmol/L of glucose ³.

Zinc shortens the episode. Zinc is a micronutrient that supports the immune system and the cells lining the gut ⁶. WHO states that zinc supplements reduce the duration of a diarrhoea episode by 25% and are associated with a 30% reduction in stool volume ¹. It is given as a dispersible tablet once a day for 10-14 days ³.

The 2024 dose change. WHO's 2024 guidelines kept zinc as a strong recommendation for children up to 10 years with acute watery or persistent diarrhoea ⁷. They added a conditional recommendation for a lower dose, 5 mg daily for up to 14 days, to reduce vomiting while keeping the benefit ⁷. The same guidelines discourage antibiotics for acute watery diarrhoea, keep ciprofloxacin for bloody diarrhoea, and do not recommend probiotics ⁷.

For a health worker, the practical message is short: ORS for every child with diarrhoea, zinc for 10-14 days, keep feeding, and antibiotics only when there is blood in the stool [3,7].

What the evidence shows

2019–2020: affordability and the zinc dose

A 2019 Ugandan cluster trial tested four ways for 118 community health workers to distribute ORS and zinc. Reported ORS use was 77% when supplies were delivered free before illness and 56% under usual sales; the adjusted gain was 19 percentage points (95% CI 13–26). Home delivery added no significant benefit over free collection ¹⁹. Follow-up was only four weeks and use was self-reported, but the trial directly identifies a household price barrier. That is a different question from whether providers prescribe according to their profit margin.

The 2020 zinc dose trial enrolled 4,500 children aged 6–59 months in India and Tanzania. Both 5 mg and 10 mg daily were non-inferior to 20 mg for diarrhoea lasting more than five days and for stool counts. Vomiting within 30 minutes occurred in 13.7%, 15.6% and 19.3%, respectively ²⁰. This direct comparison is an important predecessor to the 2024 lower-dose recommendation. It did not compare zinc with no zinc or test a mortality endpoint.

The treatment still works: two WHO-commissioned reviews

For the 2024 WHO diarrhoea guidelines, a team at Aga Khan University ran two systematic reviews commissioned by WHO [5,6].

The first compared low-osmolarity ORS with the older standard formula in children under 10 ⁵. In acute diarrhoea, low-osmolarity ORS shortened the illness (mean difference -0.28; 95% CI -0.41 to -0.15; moderate certainty) and reduced ORS intake (MD -0.18; 95% CI -0.28 to -0.07) ⁵. It reduced stool output as well, though with very low certainty ⁵. Cure within five days, treatment failure and unscheduled intravenous therapy were comparable ⁵. The authors concluded that the current WHO formula should stay ⁵.

The second pooled 38 randomised trials of zinc ⁶. In acute diarrhoea, more children recovered with zinc than with placebo (RR 1.07; 95% CI 1.03-1.10; moderate certainty), and illness was 13.27 hours shorter (95% CI 8.89-17.66 hours) ⁶. In persistent diarrhoea, recovery improved more (RR 1.75; 95% CI 1.34-2.30), but with low certainty because the studies varied widely ⁶.

Zinc caused more vomiting than placebo (RR 1.46; 95% CI 1.22-1.76) ⁶. Low doses caused less vomiting than high doses (RR 0.80; 95% CI 0.72-0.89) ⁶. That finding fed directly into WHO's new 5 mg recommendation ⁷.

GASTROSAM: one ORS for every child

Children with severe acute malnutrition have long been kept off standard ORS. Guidelines told clinicians to use a special low-sodium solution, ReSoMal, over fears of sodium and fluid overload ⁸. The GASTROSAM trial, led by Kathryn Maitland of Imperial College London, tested whether that caution was needed ⁸.

The trial ran at six hospitals in Kenya, Niger, Nigeria and Uganda between September 2019 and October 2024 ⁸. It enrolled 415 children aged 6 months to 12 years with severe malnutrition and moderate or severe dehydration, randomised to ReSoMal or low-osmolarity WHO-ORS ⁸. The primary outcome was change in blood sodium at 24 hours ⁸.

Sodium rose by 5.3 mmol/L with ReSoMal and 5.0 mmol/L with WHO-ORS (mean difference -0.6; 95% CI -1.9 to 0.7; p=0.37) ⁸. Day-28 mortality was 9% (19 children) with WHO-ORS and 12% (24) with ReSoMal (adjusted hazard ratio 0.76; 95% CI 0.41-1.41) ⁸. Clinicians watched actively for fluid overload and saw none ⁸.

The authors conclude that WHO-ORS can be used for dehydration in children regardless of nutritional status ⁸. The trial was funded by the UK Medical Research Council, the UK Department for International Development, Wellcome and Médecins Sans Frontières ⁸.

Use is rising, from a low base

A team led by Omar Karlsson with S.V. Subramanian analysed 46 Demographic and Health Surveys from 23 low- and middle-income countries ⁹. Earlier surveys dated from 2009-2014 and later ones from 2015-2023 ⁹.

Zinc treatment for child diarrhoea rose from 2% to 27%, an average of 4 percentage points a year ⁹. It increased in all 23 countries, from 9 points a year in Sierra Leone to 1 point in Cambodia ⁹.

A pooled analysis of 35 sub-Saharan African surveys covered 44,341 children with diarrhoea ¹⁰. Combined ORS and zinc use was 43.58% (95% CI 43.15-44.01) ¹⁰. Use varied with wealth, maternal education, media exposure, distance to a health facility and health insurance ¹⁰.

In India, the National Family Health Survey showed 61% of children with diarrhoea were given ORS and 31% zinc, but only about 24% got both ¹¹. Children first taken to a private hospital had 52% lower odds of receiving ORS than those taken to a government hospital ¹¹.

Why providers don't prescribe it

The most useful finding of the period came from a team led by Zachary Wagner at the RAND Corporation, published in Science ¹². They worked with 2,282 private providers in 253 medium-sized towns in Bihar and Karnataka ¹². The providers included doctors with MBBS degrees, practitioners of traditional medicine (AYUSH), rural medical practitioners and pharmacies ¹².

Trained actors posed as parents of a child with diarrhoea. The researchers ran three randomised experiments at once ¹². Some actors said they preferred ORS, some said they preferred antibiotics, and some stated no preference ¹². Providers in half of the towns were given 60 free packets of ORS, about six weeks' supply, to remove stock-outs ¹². And half of the no-preference actors said they would buy medicines elsewhere, removing the provider's profit motive ¹².

When no preference was stated, only 28% of providers prescribed or dispensed ORS, while 69% gave antibiotics ¹². When the actor said they preferred ORS, ORS prescribing rose by 27 percentage points ¹². Ending stock-outs raised it by 7 points ¹². Removing the profit motive did not change prescribing on average, though it did raise ORS at pharmacies ¹².

The team estimated that providers' belief that patients do not want ORS explains 42% of underprescribing ¹². Stock-outs explain 6% and financial incentives 5% ¹². The study was funded by the US National Institute of Diabetes and Digestive and Kidney Diseases ¹².

A follow-up study by the same group, in Science Advances in 2025, looked at antibiotics for child diarrhoea using more than 2,000 standardised patient visits in India ¹³. Seventy percent of providers prescribed antibiotics without signs of bacterial infection ¹³. Of providers who knew antibiotics were inappropriate, 62% still prescribed them ¹³. Again, the driver was the belief that patients want antibiotics, not profit or lack of alternatives ¹³. A discrete choice experiment suggested patients do not actually prefer providers who give antibiotics ¹³.

Put them in one box: Zambia's co-pack

In Zambia, ColaLife worked with the Ministry of Health to develop a co-pack of ORS and zinc ¹⁵. A study in Mongu District compared dispensing records from seven government health facilities before (2016) and after (2017) the co-pack arrived ¹⁴.

The odds of dispensing ORS and zinc together were 8.42 times higher after the co-pack (95% CI 5.47-12.9) ¹⁴. Differences between facilities narrowed, and the least-resourced facilities gained most ¹⁴.

A separate case study describes how the co-pack went national ¹⁵. National coverage of ORS and zinc rose from less than 1% in 2012 to 34% in 2018 ¹⁵. Five years after donor funding ended in 2018, an independent local manufacturer was still supplying public and private sectors on a commercially viable basis ¹⁵. A key factor was a learning and steering group chaired by the Ministry of Health that ran for eight years ¹⁵.

Two phone calls in Kwara State

At a secondary-level facility in Kwara State, Nigeria, researchers randomised 400 caregiver-child pairs ¹⁶. All received standard instructions and a picture diary. The intervention group also got phone call reminders on days three and seven of zinc treatment ¹⁶. In all, 364 pairs completed the study ¹⁶.

Full adherence to both ORS and zinc was 58.5% with reminders and 43.6% without (OR 1.82; 95% CI 1.20-2.75) ¹⁶. Zinc adherence alone rose from 60.8% to 72.1% (OR 1.671; 95% CI 1.076-2.593) ¹⁶.

Results at a glance

LimitsWhat didn't work (or the limits)

Coverage is still low. Despite fast growth, about three in four children in the 23-country analysis still did not receive zinc ⁹. Combined use in sub-Saharan Africa was under half ¹⁰, and in India about one in four ¹¹. In both places the poorest, least-educated and most remote families were least likely to be treated [10,11].

Supply fixes alone are not enough. Ending stock-outs mattered, but far less than providers' beliefs about patients ¹². Programmes that only ship more sachets will miss most of the gap. The Science study was also limited to private providers in two Indian states, and patients' stated preferences were acted out, not real ¹².

Provider profit and household price are different barriers. Removing the provider’s financial incentive did not change average prescribing in the Indian experiment ¹². In Uganda, making ORS free substantially increased reported use ¹⁹. One result does not cancel the other.

Antibiotics are the flip side. Seven in ten providers gave antibiotics to a child who did not need them, and knowledge training alone would close little of that gap ¹³. Every unnecessary antibiotic is a missed chance to give ORS and adds to drug resistance.

Zinc has a side effect. Vomiting was more common with zinc (RR 1.46) ⁶. The low-dose finding is promising, but WHO's 5 mg recommendation is conditional, and the review authors call for direct multi-country dose trials [6,7]. Countries switching dose will also need new products and labels.

The evidence reviews are not uniformly strong. The persistent-diarrhoea zinc result was low certainty ⁶. The stool-output benefit of low-osmolarity ORS was very low certainty ⁵.

GASTROSAM was a phase 2 trial. Its mortality difference was not statistically significant (p=0.39), and it was designed around sodium safety, not survival ⁸. It was open-label, and 7% of children lacked a primary outcome measurement ⁸. Larger trials would firm up the "one ORS" conclusion.

The co-pack evidence is old and small. The Mongu data come from 2016-17, were published in 2025, and use a before-after design in one district ¹⁴. They show an association, not proof of cause. The national scale-up case study is a retrospective description written by people involved in the programme ¹⁵.

The phone-reminder trial was small. It was at a single centre, open-label, and relied on caregiver diaries ¹⁶. The gain in ORS adherence alone was not statistically significant (OR 1.561; 95% CI 0.939-2.598) ¹⁶.

Treatment does not prevent diarrhoea. ORS and zinc save children who are already sick. Prevention depends on safe water, sanitation, handwashing and rotavirus vaccination ¹. GBD estimates suggest that removing all measured risk factors would cut diarrhoeal DALYs from 59.0 million to 4.99 million ².

Cost and scale

Price. ORS and zinc are among the cheapest treatments in child health. WHO says ORS costs a few cents per treatment ¹. UNICEF's 2021 indicative price for a co-pack of two one-litre ORS sachets and ten 20 mg zinc tablets was USD 0.57 ³. Zinc tablets were USD 1.33 for a carton of 100 ³. Prices fell by an average of 8% over three years as more suppliers competed ³.

Supply. UNICEF introduced co-packaged ORS and zinc to its catalogue in 2014 ³. By 2022 it had procured over 62 million co-packs, and more than twenty countries had introduced them for public-sector use ³. WHO added the co-pack to its Essential Medicines List and children's list in 2019 [3,14]. UNICEF expanded its approved ORS and zinc suppliers from two to five in 2014, including two in Africa, to shorten delivery times ³.

The gap in volume. If all 1.7 billion annual episodes were treated, it would take about four billion ORS sachets and 20 billion zinc tablets ³. In 2017-2021, UNICEF procured 254 million sachets and 3.2 billion zinc tablets ³. Most treatment in high-burden countries is bought locally or in the private sector, so UNICEF volumes are only part of the picture. But the difference shows how far supply is from need.

Who pays and delivers. UNICEF's ORS and zinc procurement depends on country programme funding ³. Delivery runs through government health facilities, community health workers under integrated community case management, and private pharmacies and clinics [3,11,12]. UNICEF and partners have pushed countries to reclassify zinc from prescription-only to over-the-counter, so it can be sold alongside ORS ³. Many countries have made that change ³.

Local manufacturing works. Zambia's experience shows a local manufacturer can keep supplying the co-pack commercially after donors leave ¹⁵. India's large programme in Uttar Pradesh and Madhya Pradesh, run with the Clinton Health Access Initiative from 2012, was later linked to a 5.27 percentage-point rise in basic child vaccination coverage (95% CI 3.48-7.05), a spillover from bringing families into contact with health services ¹⁷. That finding is from a difference-in-differences analysis, not a trial ¹⁷.

Rollout of the 2024 guidance. The move to 5 mg zinc and the simplified single ORS will need national guideline updates, training and new product presentations [7,8]. There is no published data yet on how many countries have adopted the new zinc dose.

What to watch

Confirming one ORS for all children. A randomised trial at the Children's Hospital in Lahore, run by the University of Child Health Sciences, compares low-osmolarity ORS with ReSoMal in 72 severely malnourished children with acute watery diarrhoea (NCT07026682) ¹⁸. Its primary outcome is correction of low potassium after 24 hours of rehydration ¹⁸. The registry lists it as active and not recruiting, with primary completion estimated in July 2025 ¹⁸. It is small, but it will add to GASTROSAM ⁸.

Guideline changes for severe malnutrition. GASTROSAM's authors say their results inform simpler guidelines using WHO-ORS for all children ⁸. Watch whether WHO's severe malnutrition guidance changes to match.

The right zinc dose. The Aga Khan reviewers call for multi-country trials that directly compare zinc doses, durations and side effects ⁶. Whether lower doses improve how many children finish the course has not yet been measured at scale.

Demand-side interventions. The Science and Science Advances studies point to a new kind of programme: shifting what providers believe patients want [12,13]. The obvious next step is to test campaigns that encourage caregivers to ask for ORS, or tell providers that families value it. We found no registered trial of such a campaign.

Co-packs beyond one district. The Mongu authors call for work on larger geographic scales ¹⁴. Countries now buying co-packs through UNICEF ³ could measure dispensing before and after, at low cost.

What it means

ORS and zinc do not need new science to prove they work. The 2024 evidence reviews reconfirm it [5,6], and the GBD authors credit oral rehydration as part of the four-fifths fall in child diarrhoea deaths since 1990 ². The wider window shows that affordability and prescribing behaviour both affect delivery ¹⁹¹².

For ministries of health and programme managers:

• Remove household price barriers where they limit access, alongside work on prescribing ¹⁹.
• Tackle provider beliefs. When health workers think families want ORS, they prescribe it ¹². Messages that encourage caregivers to ask for ORS, and tell providers that families value it, target the largest measured cause of underuse ¹².
• Buy and distribute ORS and zinc as a co-pack, as Zambia's Ministry of Health did [14,15]. It is on the WHO Essential Medicines List ³.
• Make zinc available over the counter alongside ORS, as UNICEF recommends ³.
• Use low-cost reminders to help families finish the zinc course ¹⁶.
• Update national guidelines for the 2024 WHO recommendations: 5 mg zinc, no antibiotics for watery diarrhoea ⁷.

For nutrition programmes: GASTROSAM supports simplifying treatment so severely malnourished children can receive standard WHO-ORS ⁸. That means one product, one protocol, and fewer chances for error.

For clinicians and community health workers: Give ORS to every child with diarrhoea, and zinc for 10-14 days [3,7]. Do not wait for the family to ask. Reserve antibiotics for bloody diarrhoea ⁷. Most families do not prefer a provider who gives antibiotics ¹³.

For funders: The co-pack costs well under a dollar ³. Fund both affordable access and uptake: a cheap product can still be unaffordable to a household ¹⁹. The figure to watch is combined ORS and zinc coverage ¹⁰. Sierra Leone's pace of 9 points a year for zinc shows how fast it can move ⁹. Every child still missing out is a gap in delivery, not in knowledge.