How to Rehydrate Someone Properly When There Is No IV

By the Jase Medical Team

When someone is losing fluid from vomiting or diarrhea, rehydration isn’t simply a matter of getting them to drink something.

The type of fluid matters. The amount matters. And especially when someone is vomiting, the rate matters.

That’s the science behind oral rehydration therapy, a remarkably effective approach to dehydration that has been used around the world for decades. The World Health Organization’s oral rehydration solution (ORS) contains glucose and sodium in carefully balanced concentrations, 75 mmol/L of each, with a total osmolarity of 245 mOsm/L. The glucose helps the intestine absorb sodium, and sodium helps bring water with it.

In other words, oral rehydration isn’t just “drink more water.”

It’s using the gut’s own transport system to move water back into the body.

An Electrolyte Drink Isn’t Necessarily an Oral Rehydration Solution

Walk down the hydration aisle and you’ll see sports drinks, electrolyte powders, flavored waters, hydration packets, and products promising rapid hydration.

They aren’t all the same thing.

A true oral rehydration solution is formulated with a specific balance of glucose and electrolytes designed for replacing fluid lost through illnesses such as diarrhea and vomiting. WHO’s reduced-osmolarity ORS contains 75 mmol/L of sodium and 75 mmol/L of glucose.

That is different from a beverage designed primarily for exercise, flavor, or everyday hydration.

So if someone is dehydrated from a stomach illness, prepackaged oral rehydration solution should be your first choice when it’s available. Look for a product specifically labeled for oral rehydration rather than assuming anything marketed as an “electrolyte drink” serves the same purpose.

And don’t assume you can turn a sports drink into ORS simply by diluting it. Adding water changes all of its concentrations—including the sodium you’re trying to replace.

When Someone Is Vomiting, How They Drink Matters

One of the most common problems with oral rehydration happens when a very thirsty person tries to drink a large amount at once.

Their stomach may send it right back up.

Instead, oral rehydration can be given in small, frequent amounts and gradually increased as tolerated. CDC guidance for children with vomiting describes starting with about 5 mL, roughly one teaspoon, every five minutes and increasing gradually. A spoon or oral syringe can make those small amounts easier to control.

That may feel painfully slow when a child is thirsty and you know they need fluid. But getting a small amount to stay down repeatedly can be more useful than having them drink a large glass and vomit it back up.

Vomiting also doesn’t automatically mean oral rehydration has failed. CDC guidance notes that most children with vomiting accompanying acute gastroenteritis can still be successfully rehydrated orally when ORS is given in limited, frequent amounts.

How Much Oral Rehydration Solution Does Someone Need?

This is where age, weight, degree of dehydration, ongoing fluid losses, and medical history matter.

For children, clinicians use weight-based approaches to determine how much fluid is needed for rehydration and how much additional ORS should be given to replace continuing losses from diarrhea or vomiting. WHO guidance also provides age-based amounts of ORS after loose stools when preventing dehydration: for example, 50–100 mL after each loose stool for children under 2 and 100–200 mL for children ages 2–10.

That doesn’t mean every sick child should be managed at home by calculating a formula.

If you’re unsure how much fluid a child needs, or you’re concerned they’re already significantly dehydrated, contact their pediatrician or another qualified medical professional.

The useful household principle is simpler: oral rehydration isn’t one big drink. It’s a process of replacing what has already been lost while continuing to replace what the person is still losing.

What If You Don’t Have Commercial ORS?

Prepackaged oral rehydration solution is preferable because the concentrations have already been measured for you. WHO describes ORS as a pharmaceutical product and recommends manufacturing it according to quality standards.

If proper ORS truly isn’t available, a homemade sugar-and-salt solution may be used as an emergency fallback following established public-health instructions.

Do not improvise the proportions.

Too much salt can be dangerous, particularly for infants and young children. Don’t use heaping spoonfuls, estimate quantities by eye, or decide that making the solution “stronger” will make it work better.

For that reason, we recommend keeping commercially prepared ORS packets or ready-to-use oral rehydration solution available rather than relying on memory for an emergency recipe.

If you do need to make a homemade solution, use a recipe from a recognized public-health authority and follow the measurements exactly using level measures and the specified amount of clean water.

Pedialyte vs. Gatorade: Does It Matter?

For ordinary exercise or replacing fluid after sweating, a sports drink may be perfectly reasonable for many people.

But rehydrating someone who is losing significant fluid through vomiting or diarrhea is a different job.

Products formulated as oral rehydration solutions are designed around the balance of glucose and electrolytes needed to promote absorption and replace losses. Sports drinks are formulated for a different purpose and may contain considerably different amounts of sodium and sugar.

So when the problem is dehydration from gastroenteritis, don’t choose solely by which bottle says “electrolytes” on the front.

Look for an actual oral rehydration solution.

When Oral Rehydration Stops Being a Home Problem

Oral rehydration is powerful, but it isn’t appropriate for every situation.

Severe dehydration or shock requires urgent medical treatment and may require IV fluids. CDC guidance specifically identifies shock or near-shock as situations requiring initial IV treatment.

Seek urgent medical care for concerning signs such as severe lethargy or difficulty waking, confusion, fainting, very little or no urine, inability to keep even small amounts of fluid down, blood in the stool or vomit, severe abdominal pain, or other signs that the person is becoming seriously ill.

Infants deserve an especially low threshold for contacting a pediatrician because dehydration can progress quickly.

And if your instinct is telling you that someone is getting worse rather than better, don’t let the fact that you’re giving ORS create false reassurance. Oral rehydration is a treatment tool, not a substitute for medical evaluation when someone is seriously ill.

Why Knowing Oral Rehydration Still Matters

It’s easy to think of IV fluids as the “real” treatment and oral fluids as the backup.

The healthcare system has repeatedly been reminded why that isn’t always true.

After Hurricane Helene damaged Baxter’s North Cove manufacturing facility in 2024, the disruption affected a facility that had been producing approximately 60% of the IV solutions used each day in the United States. Hospitals and health systems had to conserve IV fluids and reconsider when patients could safely receive hydration through other routes.

But households never had an IV bag hanging in the kitchen in the first place.

What you can have is an appropriate oral rehydration solution and an understanding of how to use it: the right fluid, the right amount, and the right pace.

At Jase Medical, we’re a family team of physicians, PAs, and pharmacists focused on appropriate medical preparation. That doesn’t mean trying to turn your home into an emergency department. It means understanding which simple, evidence-based tools can help when ordinary access to care is delayed and knowing exactly where home care needs to stop.

For vomiting and diarrhea, that starts with something surprisingly basic:

Don’t just replace water. Rehydrate properly.

The Jase Medical Team is a family team of medical doctors, PAs, and pharmacists focused on appropriate medical preparation: clinically grounded readiness that complements, rather than replaces, the healthcare professionals you already trust.

This article was prepared by the Jase Medical content team for informational purposes only and does not constitute medical advice. Prescription requirements, emergency dispensing rules, insurance coverage, and controlled-substance regulations vary by medication, jurisdiction, and individual circumstances. Consult a licensed healthcare provider or pharmacist regarding your specific medications.