The World Health Organization (WHO) identifies dehydration as the most severe immediate threat from acute diarrhea. WHO says liquid stools and vomiting remove water and electrolytes, and recommends oral rehydration salts (ORS) solution to replace those losses.

People who remain alert and can drink can begin replacing fluids at home, but the response should depend on symptoms and risk factors. Small, repeated sips may be easier to retain when nausea is present; severe dehydration or shock requires medical treatment and may require intravenous fluids.

Blood, dehydration and altered alertness require prompt care

Blood in the stool, persistent vomiting that prevents drinking, or signs of dehydration require prompt clinical assessment. Reduced urination, dark urine, a dry mouth, dizziness, unusual tiredness or increasing weakness can accompany dehydration. Confusion, unusual drowsiness, poor responsiveness, pale or mottled skin, cold hands or feet, severe breathing difficulty or collapse require emergency care.

Severe or sudden abdominal pain, a swollen or very tender abdomen, vomit containing blood or material resembling coffee grounds, and green vomit also need urgent assessment. Local emergency numbers and routes into care differ by country.

Do not rely on one universal cutoff measured in hours without urination. Age, usual urine pattern, ongoing losses and other symptoms all affect the assessment. The UK National Health Service (NHS) advises urgent clinical help for bloody diarrhea, an inability to keep fluids down, or continuing signs of dehydration after ORS use.

A person sits with one hand on their forehead while feeling unwell (illustrative image)

Replace water and electrolytes in small, repeated amounts

Packaged ORS is designed to replace both water and electrolytes lost through diarrhea. Prepare it with the amount of safe water stated on the packet and do not make the finished solution weaker or stronger. When vomiting or nausea makes drinking difficult, start with small, frequent sips and increase gradually as tolerated.

WHO and UNICEF’s ORS standard describes a glucose-electrolyte formulation that can treat dehydration from diarrhea in all age groups except the most severe cases. The document is a pharmaceutical manufacturing standard, not a household recipe. APPI News therefore does not reproduce its ingredient weights as instructions for mixing a kitchen substitute.

Water and other tolerated fluids can help maintain intake in mild illness, but they do not all have the same electrolyte composition as ORS. The US Centers for Disease Control and Prevention says sports drinks do not replace diarrheal fluid losses correctly and recommends ORS when diarrhea is severe. Very sugary drinks, fruit juice and carbonated drinks can worsen diarrhea and should not replace ORS.

Food can continue as tolerance returns

Adults do not need to fast until diarrhea ends. Eat when able, beginning with small portions if nausea or appetite loss makes a usual meal difficult. Rich, fatty or spicy foods may be harder to tolerate during early recovery.

Infants should continue breastfeeding, including during rehydration. Formula should remain at its usual strength rather than being diluted. Once a child has been rehydrated, usual milk and solid foods can return according to the child’s tolerance and clinical advice.

Common substitutions can create new problems

Do not mix an ORS packet with an estimated volume of water, add extra powder, or dilute a prepared product to make it last longer. A solution with the wrong concentration no longer matches the formulation on which the instructions are based. Use safe water and follow the product label.

Do not automatically use medicine to stop diarrhea. Suitability depends on age, the suspected cause, pregnancy, other health conditions and whether fever or blood is present. The NHS says children younger than 12 should not receive medicine to stop diarrhea, while the CDC advises avoiding bowel-slowing medicines when diarrhea occurs with blood or high fever.

A bottle of sports drink stands on a table (illustrative image)

Children, pregnancy and chronic illness need separate decisions

Infants and children

Young children can lose fluid quickly, and adult instructions should not be applied to them. The NHS advises continuing breast or bottle feeds, using smaller feeds more often if vomiting occurs, and never weakening infant formula. A baby under 12 months, a child who stops feeding, or a child with fewer wet diapers, poor drinking, persistent vomiting or unusual sleepiness needs prompt pediatric advice.

Pregnancy

APPI News could not find an international clinical guideline that sets a different ORS protocol for uncomplicated acute diarrhea during pregnancy. Pregnant people who cannot keep fluids down, have blood in the stool, develop dehydration signs or are concerned about medicine use should contact a maternity or medical clinician. They should not apply general advice about antidiarrheal medicines without a clinician or pharmacist checking the specific product and pregnancy.

Chronic illness, older age and regular medicines

People with kidney or heart disease may already have individualized instructions about fluid or electrolyte intake. Diabetes, weakened immunity, older age and some medicines can also change the risks created by diarrhea or dehydration. These groups should contact a clinician or pharmacist early and follow any existing sick-day plan rather than changing medicines or fluid limits on their own.

A caregiver holds a bottle while feeding an infant (illustrative image)

Frequently asked questions

Is an oral rehydration solution better than plain water?

ORS supplies glucose and electrolytes with water, so it is intended to replace diarrheal losses. Water can contribute to fluid intake in mild illness, but severe diarrhea or signs of dehydration warrant ORS and clinical advice.

Can a sports drink replace ORS?

No. The CDC says sports drinks do not replace fluid and electrolyte losses correctly in severe diarrheal illness. Use an ORS product prepared according to its label.

Should someone with diarrhea stop eating?

No fixed fasting period applies to everyone. Adults can eat when able, and children can resume their usual food after rehydration; breastfeeding should continue.

When does diarrhea need medical assessment?

Blood in the stool, inability to retain fluids, reduced urination, altered alertness, severe abdominal pain or other dehydration signs require prompt assessment. Shock signs, collapse, severe breathing difficulty or poor responsiveness require emergency care.