What should you know about dehydration?

Fluid can be lost through diarrhoea, vomiting, fever, sweating, or increased urination. Early clues include thirst, dry lips or mouth, headache, tiredness, dizziness, and urine that is darker than usual. Constipation can also occur when the bowel has too little water.

Dehydration may accompany gastroenteritis or heat exhaustion. Cloudy or dark urine alone does not identify the cause, and urinary symptoms can also occur with a urinary tract infection or kidney stones.

Take regular small sips of water or an oral rehydration drink, especially after vomiting or diarrhoea. Rest in a cool place if heat has contributed, and resume ordinary food as tolerated. Infants, older adults, and people with kidney or heart problems may need individual advice about fluid intake rather than a general plan.

Get urgent medical help for confusion, fainting, severe weakness, inability to keep fluids down, very little or no urine, rapid breathing, or worsening dizziness. A child who is difficult to wake, has no tears, or is drinking poorly needs prompt assessment. Seek care when fluid loss continues or an underlying illness is suspected.

Ask which rehydration drink is suitable, whether medicines could be increasing fluid loss, how to monitor urine and alertness, and whether symptoms suggest gastroenteritis, heat exhaustion, a urinary tract infection, or kidney stones.