For Clinicians | Oral Rehydration When IV Fluids Aren’t Available

By Dr. Jamie Wilkey, PharmD, Director of Clinical Education
Medically reviewed and edited by Kristen Carpenter, PA-C

Hi again, it’s Jamie, your pharmacist who loves writing about appropriate medical preparation.

In the past we’ve focused on specific medications and natural disasters, but haven’t properly covered hydration. Today we are fixing that! Getting fluids into someone when an IV isn’t available, or when it’s just not convenient. Sometimes that’s a real access problem. More often it’s 9pm, urgent care closed at 8, and you’re standing in your own kitchen holding a liquid that a sick kid has decided is their mortal enemy.

I’ve dealt with this from behind the counter and I’ve dealt with it at home as a mom of 4 boys. Today we’re covering what oral rehydration is, what it does, and how it works; especially without an IV available. I’ll speak generally about kids specifically in this article, but it applies to teens and adults (you kids at heart) as well. 

Why plain water doesn’t rehydrate

Quick refresher, because this is one of those things we all learned and then filed away. I know I needed this refresher to write this article.

A patient who is vomiting and having diarrhea isn’t just down a volume of water. They’re down sodium, potassium and chloride, and they’re losing more with every episode. Plain water replaces the volume, but none of the salts. If the patient is only drinking water and still has ongoing losses then the plain water dilutes the sodium that’s left. Juice, soda and broth have either too much sugar, not enough sodium, or sodium with nothing to carry it across those cell membranes. 

Before I wrote this article I thought off the top of my head that an oral rehydration solution is a salt delivery system and the sugar is just in there for taste. But I was wrong! The sugar is the mechanism to get the salts out of the gut and into the blood stream.

One of the doors into the gut wall only opens when glucose and sodium show up together. They cross the wall coupled, and water follows the sodium across by osmosis. That’s why an oral rehydration solution is built at roughly equal parts sodium and glucose. ¹ The ratio is the design. Enough glucose to work that door, and no more than that, because sugar past that point doesn’t move any more sodium and it raises the osmolarity of what’s sitting in the gut, which pulls water in the wrong direction.

Plenty of drinks contain both. Very few contain them in the amounts that make the transport work. Both ingredients being present doesn’t make something an oral rehydration solution.

What to use, and what to make when there’s nothing in the house

A packaged oral rehydration solution is the first choice every time. It’s already mixed to the ratio, and it carries two things the kitchen version can’t: potassium, to replace what’s going out in the stool, and citrate, which buffers the acidosis that comes with it. Nobody has to measure anything at 2am.

Here’s the recipe for a rehydration solution made at home: one litre of clean water, 3 g of table salt, and 18 g of sugar, which is about four level teaspoons. ¹

WHO writes that 3 g as “one level teaspoonful.” Don’t pass that along to an American patient. A level US teaspoon of table salt holds closer to 6 g, the full 2,300 mg of sodium you see on a nutrition label, and it doubles the salt in the litre. Counsel half a level teaspoon, or 3 g on a kitchen scale. Level spoons for the sugar too, not heaping ones, and not a soup spoon out of the drawer.

* And one note for those of you doing the math in your head wondering how in the heck this salt and sugar recipe is a 1:1 ratio. Eighteen grams of sugar against 3 g of salt doesn’t look like equal parts of anything. The molecule counts are the same though. A sugar molecule weighs about six times what a unit of table salt weighs, so 6 to 1 by weight comes out to 1 to 1 by molecule. What the transporter responds to is how many molecules of each are in the glass, not how much they weigh.

WHO prints that recipe and then says it isn’t generally recommended, for three specific reasons: the recipe gets forgotten, the ingredients aren’t always there, and people end up giving too little of it. ¹ That caution is written for public health programs deciding what to teach at scale. We at Jase are usually talking to someone whose options have already narrowed to what’s in the kitchen, and for them a recipe they can remember beats a packet they can’t reach. Know it. Use it when there’s nothing better.

So the counseling on this is to for sure use a proper rehydration packet if your patients have one or can reasonably get access to one. If they’re mixing it themselves, have them use an actual measuring spoon and level it off, because the difference between a level teaspoon and a heaping one is a big difference, especially for kids.

The homemade version carries no potassium and no citrate. It’s the bridge to getting a rehydration packet, not a complete replacement for one.

Most electrolyte drinks are not oral rehydration solutions

I’m guilty of this one too. If the label said electrolytes, I assumed it would do the job for a kid who needed fluids.

So, here’s the yardstick. An oral rehydration solution built at the WHO ratio, poured into a 16 oz glass, is about 800 mg of sodium and about 6 g of sugar. ¹ WHO set that 75 mmol/L by lowering it from an older 90, because less sodium worked better in ordinary childhood diarrhea than the cholera-era formula did. The studies behind that change ran down to 50 mmol/L, so the American products sitting under 75 are sitting inside the evidence, not outside it. Anywhere in that range is an oral rehydration solution. Far below it is a beverage.

• Pedialyte Classic: about 520 mg sodium, about 7 g sugar ²
• DripDrop: about 660 mg sodium, about 14 g sugar³
• Gatorade Thirst Quencher: about 216 mg sodium, about 27 g sugar⁴
• LMNT: 1,000 mg sodium per stick, zero sugar⁵

Pedialyte lands in range. It’s the only one on the list that was built for this, and it shows on both numbers.

DripDrop gets the sodium into the neighborhood and then doubles the sugar. The idea is right; the sugar is twice what the transport needs, and the extra is the part that raises osmolarity. Probably not a big deal clinically, but not ideal.

Gatorade misses on both ends, a quarter of the sodium and more than four times the sugar. That isn’t a mistake on their end. It’s built to replace what comes out in sweat during a workout, not what comes out in stool during a rotavirus.

LMNT is the big example of a drink that isn’t going to help here, and it’s the poster child I’d use to teach this whole thing. All salt, no sugar at all. Go back to that door in the gut, the one that only opens when salt and sugar show up together. Without the sugar, the salt doesn’t have a ride across. It sits in the gut, pulls water in with it, and makes a miserable kid more miserable.

How much they need to drink, and how fast

So now we know what should be in the cup. That’s one part of it…but not the end. We still have to know how much they need to drink and how often, because the right liquid in the wrong amount doesn’t rehydrate anybody.

The working numbers are 50 mL per kilogram over four hours for mild dehydration, 100 mL per kilogram for moderate, plus another 10 mL per kilogram after each diarrheal stool, capped at about a cup per stool.⁶ WHO’s plan for a small child uses a flat 75 mL per kilogram. ¹

In kids, for mild dehydration:

A 2-year-old at 30 lb needs about 680 mL over four hours. Call it three cups.
A 10-year-old at 80 lb needs about 1.8 litres. Seven or eight cups.

Double both of those if they’re moderately dehydrated. One problem with doubling it. You’re now asking a 2-year-old to drink a cup and a half an hour. WHO says a kid that size tops out around a cup.¹

For an adult the weight formula stops being useful, and the instruction becomes replacing what’s going out: about a cup after every loose stool, and drinking to thirst rather than on a schedule.

Especially for kids, this goes by spoon or cup, never a bottle.¹ WHO’s rate for a child under 2 is a teaspoonful every one to two minutes. Older kids and adults can take frequent sips straight from the cup.¹ If they’re vomiting, start slower, around a teaspoon every five minutes, and build up as they keep it down.⁶ A big gulp on an irritated stomach comes right back. And if they do vomit, wait 5 to 10 minutes and start again more slowly, a spoonful every two or three minutes.¹

The spacing is the whole thing. A teaspoon every five minutes, held there for four hours, comes to about one cup. Every one to two minutes gets you somewhere between two and five. The 2-year-old needs three. So five minutes is where you start when they’re throwing up, not where you stay.

When they can’t keep anything down

And this is where oral rehydration falls apart out there in the real world. Not on the science. Because it’s a lot of liquid, it generally tastes awful, and a sick kid fights every ounce of it. The kid who throws up the first three teaspoons makes the family quickly lose faith in this rehydration approach because it can be so hard and stressful to help kids who are miserable keep the dang liquid down. I know, because I’ve been there many late nights with my own boys and I was ready to pull my hair out because it feels like there’s no way to get liquid down a gullet that doesn’t want to swallow. 

Ondansetron is the medication for this with solid evidence. In 2006 a trial was run with 215 children between 6 months and 10 years with gastroenteritis and mild to moderate dehydration. They got a single oral dose or placebo, then started a standardized rehydration protocol. Vomiting during rehydration: 14% with ondansetron, 35% with placebo. Needing IV fluids: 14% versus 31%.⁷

Then in July 2025 a much larger trial tested children 6 months to 18 years who went home from six pediatric emergency departments with six doses of ondansetron or placebo for caregivers to give over the next 48 hours as vomiting continued. Moderate to severe gastroenteritis over the following week: 5.1% with ondansetron, 12.5% with placebo.⁸ Side effects were comparable between groups, with a small increase in diarrheal stools among the children who took three doses or more.

So, if throwing up or severe nausea is a problem, give an antiemetic first, then the fluid. Ondansetron doesn’t treat the illness itself. It buys the window where oral rehydration can actually succeed.

The treatment layer that doesn’t exist

A family either reaches a clinician or they’re alone with whatever is in the cabinet. What’s usually in their house is a sports drink. There’s nothing sanctioned in between.

Hospitals hit a similar wall twice in seven years. Hurricane Maria took out Baxter’s Puerto Rico plants in 2017. Helene took out North Cove in 2024, the plant making roughly 60% of the country’s IV fluids.⁹ Surveyed afterward, most affected hospitals had converted IV medications to oral, and well over half had written themselves an oral hydration protocol.¹⁰ They built the middle layer under pressure, because the alternative had disappeared.

That right there is the layer we work on at Jase, and appropriate medical preparation is what we call it: the clinical decision made ahead of the illness instead of during it, so the person standing in the kitchen at 9pm already has the right rehydration packet and a plan for how often to give it. Whether an antiemetic belongs in a particular house is a prescribing decision. A licensed provider reviews every Jase request and writes the prescription, and anything dispensed that way is for emergency use only, after first trying to reach a qualified provider.

None of this replaces primary care. It complements it, for the hours when primary care isn’t reachable. If this is a conversation you’d rather hand off in your own clinic, you can refer patients to us, and we’ll keep publishing the criteria we use so you can judge them yourselves.

Where oral rehydration stops

Now I want to make it really, really clear: oral rehydration is only for mild to moderate dehydration. It is not the answer for severe dehydration, shock, or a child who isn’t mentally there. That really does require an IV, and urgently.

If you’re having trouble judging how severe it is, here’s the general checklist. Lethargic or unconscious. Sunken eyes. Skin that tents and stays tented. Not able to drink at all.¹ Two or more of those are past what a cup is going to fix, and they need to get to care with an IV urgently.

The end!

Thanks for joining us on dehydration. Dehydration shows up from so many different directions: throwing up and diarrhea, sure, but also a fever that runs for days, a sore throat or mouth sores that make a kid refuse to drink, a hot afternoon with too much play and not enough water, and plain lack of access to clean water. The cause changes. The ratio, the volume and the rate don’t.

Sources

1. World Health Organization. The Treatment of Diarrhoea: A Manual for Physicians and Other Senior Health Workers. 4th rev. Geneva: WHO; 2005. Source for the reduced-osmolarity ORS composition (sodium 75 mmol/L, glucose 75 mmol/L, total osmolarity 245 mOsm/L), the home-made salt and sugar solution and WHO’s reasons for not generally recommending it, Treatment Plan B at 75 mL/kg over four hours, administration by spoon or cup rather than a bottle with a 5 to 10 minute pause after vomiting, and the Table 1 signs used to classify severe dehydration.. https://www.who.int/publications/i/item/9241593180
2. Abbott Nutrition. Pedialyte Classic. Nutrition panel read 21 September 2026: 390 mg sodium and 5 g total sugars per 12 fl oz (360 mL), which works out to about 520 mg sodium and about 7 g sugar per 16 fl oz. https://www.abbottnutrition.com/our-products/pedialyte-classic
3. DripDrop. Product FAQ. Read 21 September 2026: 660 mg sodium per 16 fl oz prepared, with about 14 g sugar per 16 fl oz. https://dripdrop.com/pages/faq
4. Gatorade. Gatorade Thirst Quencher, 20 fl oz. Product FAQ read 21 September 2026: about 270 mg sodium per 20 fl oz, which works out to about 216 mg per 16 fl oz. Total sugars of 34 g per 20 fl oz, about 27 g per 16 fl oz, from the nutrition panel recorded 18 September 2026. https://www.gatorade.com/sports-drinks/gatorade-thirst-quencher/orange
5. LMNT. Ingredients and formulation. Read 21 September 2026: 1,000 mg sodium, 200 mg potassium and 60 mg magnesium per stick, and no sugar. https://drinklmnt.com/pages/ingredients
6. Merck Manual Professional Edition. Oral Rehydration Therapy. Confirmed 21 September 2026: 50 mL/kg over four hours for mild dehydration and 100 mL/kg for moderate, an additional 10 mL/kg (up to 240 mL) for each diarrheal stool, starting at 5 mL every five minutes and increasing as tolerated. https://www.merckmanuals.com/professional/pediatrics/dehydration-and-fluid-therapy-in-children/oral-rehydration-therapy
7. Freedman SB, Adler M, Seshadri R, Powell EC. Oral ondansetron for gastroenteritis in a pediatric emergency department. N Engl J Med. 2006;354(16):1698-1705. Single oral dose of orally disintegrating ondansetron versus placebo in 215 children aged 6 months through 10 years, given before a standardized oral rehydration protocol. Vomiting during rehydration 14% versus 35% (RR 0.40, 95% CI 0.26 to 0.61); intravenous rehydration 14% versus 31% (RR 0.46, 95% CI 0.26 to 0.79). Hospital admission rates did not differ between the groups. https://pubmed.ncbi.nlm.nih.gov/16625009/
8. Freedman SB, Williamson-Urquhart S, Plint AC, et al., for the Pediatric Emergency Research Canada Innovative Clinical Trials Study Group. Multidose ondansetron after emergency visits in children with gastroenteritis. N Engl J Med. 2025;393(3):255-266. Randomized, double-blind trial in six Canadian pediatric emergency departments; 1,030 children aged 6 months to under 18 years received six take-home doses of ondansetron or placebo for use over 48 hours. Moderate-to-severe gastroenteritis over the following 7 days occurred in 5.1% versus 12.5% (adjusted odds ratio 0.50, 95% CI 0.40 to 0.60). https://pubmed.ncbi.nlm.nih.gov/40673584/
9. American Hospital Association. Supply chain updates following temporary closure of Baxter’s plant in North Carolina due to Hurricane Helene. 2024. Source for the North Cove facility supplying roughly 60% of US IV solutions. https://www.aha.org/special-bulletin/supply-chain-updates-following-temporary-closure-baxters-plant-north-carolina-due-hurricane-helene
10. Gorgens S, Alshadad A, Malek A, et al. The impact on healthcare facilities of the 2024 IV fluids shortage after Hurricane Helene: a mixed methods study. PLoS One. 2026;21(4):e0344524. Survey of 17 respondents drawn from a 200-member national critical care task force, an 8.5% response rate: 88.2% of hospitals affected by the shortage, 58.8% created an oral hydration protocol, 81.3% converted IV medications to oral. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0344524