What could dehydration mean?

Dehydration means the body has lost more fluid than it has taken in. Thirst, dry mouth, dark urine, peeing less, dizziness and tiredness are common. Babies and young children may have fewer wet nappies, no tears or become unusually sleepy or irritable.

Is dark urine a sign of dehydration?

It can be. Dark, strong-smelling urine and peeing less often are common signs, although medicines and health conditions can also change urine colour.

Is water enough for dehydration?

Water may be enough for mild fluid loss. Oral rehydration solution is useful when vomiting or diarrhoea also causes salt loss.

How can I tell if a baby is dehydrated?

Look for fewer wet nappies, no tears, dry mouth, sunken eyes, poor feeding, unusual sleepiness or irritability. Seek urgent advice.

Dehydration: When to See a GP

Replacing fluids

Take small sips and gradually increase. A pharmacist can advise on oral rehydration solution. Keep giving breast milk or normal-strength formula unless a clinician advises differently.

Avoid unsuitable drinks

Fruit juice and fizzy drinks can worsen diarrhoea in children. Do not make infant formula weaker, and do not use homemade salt-and-sugar mixtures when commercial oral rehydration products are available.

Higher-risk situations

Ask for advice early for babies, frail older adults, pregnancy, diabetes, kidney disease or medicines affected by dehydration.

Common questions about dehydration

Is dark urine a sign of dehydration?: It can be. Dark, strong-smelling urine and peeing less often are common signs, although medicines and health conditions can also change urine colour.
Is water enough for dehydration?: Water may be enough for mild fluid loss. Oral rehydration solution is useful when vomiting or diarrhoea also causes salt loss.
How can I tell if a baby is dehydrated?: Look for fewer wet nappies, no tears, dry mouth, sunken eyes, poor feeding, unusual sleepiness or irritability. Seek urgent advice.

Sources

NHS — Dehydration

How we reviewed this page

Medically reviewed by the HealthAnswers UK doctor review panel

First published: 1 August 2026
Medically reviewed: 1 August 2026
Next review due: 1 August 2029 or sooner if NHS or NICE guidance changes

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