Dehydration and fatigue

When you lose more fluid than you replace, your body may respond with thirst, dry mouth, headache, dizziness, weakness and reduced concentration. Fatigue may follow sweating, fever, vomiting, diarrhoea or a day of poor intake. It can also come from anaemia, infection, sleep problems, medication effects or other conditions, so tiredness alone cannot identify dehydration.

Drink small amounts regularly and choose water with meals. If fluid loss followed vomiting or diarrhoea, an oral rehydration solution can replace water and salts when prepared and taken according to its instructions. Rest, avoid strenuous activity and cool down after heat exposure. A gradual return to normal eating and drinking is sensible when nausea settles. Notice urine colour and frequency as useful supporting clues.

Get urgent help for confusion, fainting, severe weakness, difficulty breathing, inability to keep fluids down or very little urine. Arrange medical advice if fatigue is severe, keeps returning, follows heavy bleeding, or remains after you have resumed drinking and eating. Assessment may include checking circulation, hydration, medicines and other causes of low energy.

Ask which fluids are appropriate for you, whether your medicines affect hydration, and whether persistent fatigue should be checked for anaemia, infection or another condition.