Dehydration

Overview

Dehydration happens when the body loses too much water and electrolytes. If it continues, circulation to vital organs can fall and shock can develop.

The main causes covered here are diarrhoea and vomiting. Severe burns and severe acute malnutrition need different protocols.

Children are especially vulnerable because they lose fluid quickly, have a high surface-area-to-volume ratio, and may not be able to explain thirst or replace fluids independently.

Clinical features and assessment

Start with a history of diarrhoea or vomiting and ask about reduced urine output. Then classify the degree of dehydration from clinical signs.

Dry mouth and absent tears may be present, but the key decision is whether the person has severe dehydration, some dehydration, or no dehydration.

Patients with severe dehydration should also be assessed for shock, including tachycardia, low blood pressure, weak pulse, and delayed capillary refill.

Electrolyte problems may cause fast breathing, muscle cramps, weakness, irregular heartbeat, palpitations, confusion, or seizures.

• Sunken eyes may be normal in some children; compare with the child's usual appearance when possible.
• Skin pinch is checked on the abdomen without twisting the skin. In older people, this sign is less reliable because skin elasticity changes with age.

Severe dehydration: WHO Treatment Plan C

Severe dehydration is an emergency. Treat shock first if it is present. If the patient can drink, give oral rehydration solution while IV access is being obtained.

Use Ringer lactate when available and monitor the infusion rate closely. If Ringer lactate is not available, 0.9% sodium chloride can be used.

Use a large peripheral IV catheter when possible, or an intraosseous needle when IV access cannot be obtained quickly.

• Repeat the first 30 ml/kg phase once if the radial pulse remains weak or absent after the first bolus.
• If severe anaemia is suspected, measure haemoglobin and manage anaemia in parallel. If transfusion is needed, give blood through a separate IV line and deduct that volume from the planned fluid total.
• As soon as the patient can drink safely, usually within about 2 hours, give ORS as tolerated.
• Monitor ongoing losses and reassess clinical condition and dehydration degree regularly.

Monitoring during IV rehydration

• If the patient remains or becomes lethargic, check blood glucose and treat hypoglycaemia when needed.
• If muscle cramps, weakness, or abdominal distension develop, consider moderate hypokalaemia. Potassium replacement should be inpatient-only and guided by local protocol and monitoring.
• If peri-orbital or peripheral oedema develops, reduce IV fluid to the minimum, listen to the lungs, reassess dehydration severity, and continue only if IV rehydration is still required.
• If shortness of breath, cough, and basal lung crackles develop, sit the patient upright, reduce the infusion rate, consider fluid overload management, and monitor closely.
• If available, blood tests can help monitor urea and electrolyte problems.

Some dehydration: WHO Treatment Plan B

Some dehydration is treated with oral rehydration solution over 4 hours, with close reassessment. Encourage continued age-appropriate fluid intake, including breastfeeding.

Give additional ORS after each loose stool and monitor ongoing losses. Escalate care if signs worsen or drinking is not safe.

• Reassess regularly because some dehydration can progress to severe dehydration if losses continue.
• If the patient cannot drink safely, vomits persistently, or develops severe signs, move to urgent facility management.

No dehydration: WHO Treatment Plan A

When there are no signs of dehydration, the goal is to prevent dehydration while the diarrhoea or vomiting continues.

Encourage age-appropriate fluids and continue breastfeeding in young children.

• Give ORS after every loose stool.
• Treat the underlying cause when specific treatment is required.
• Return for care if thirst, reduced urine, persistent vomiting, blood in stool, fever, weakness, or any danger sign appears.

Treatment of diarrhoea alongside rehydration

In diarrhoeal illness, rehydration must match the dehydration category, but additional diarrhoea care is still needed.

• Administer aetiologic treatment when a specific cause requires it.
• Children under 5 years should receive zinc sulfate according to local or linked drug guidance.
• Use adapted protocols for children with severe acute malnutrition.
• For more detailed ORS recommendations in cholera contexts, use a cholera-management guideline.

Special protocols and exclusions

• The protocol on this page is focused on dehydration caused by diarrhoea and vomiting.
• Children with severe acute malnutrition need a separate adapted dehydration approach.
• Patients with severe burns need burns-specific fluid management.
• Patients with shock should be managed according to the shock pathway before and during rehydration.

Source references

• World Health Organization. The treatment of diarrhoea: a manual for physicians and other senior health workers, fourth revision, 2005.
• World Health Organization. Pocket book of hospital care for children.
• MSF cholera-management guidance is referenced by the source for more detailed ORS recommendations by age and weight in cholera settings.