What should you know about dehydration in winter?

Cool weather may blunt thirst, so you may drink less while your body still loses water through breathing and urine. Indoor heating can make air dry, and warm clothing can lead to sweating during exercise. Fever, vomiting, and diarrhoea can remove fluid and salts quickly; gastroenteritis is one possible cause. Dark urine, a dry mouth, headache, tiredness, dizziness, and passing urine less often can be clues. Dehydration can also make constipation more likely and may contribute to kidney stones.

Sip fluids regularly through the day rather than waiting for thirst. Water is suitable for many people; soup or an oral rehydration solution may help when vomiting or diarrhoea has caused substantial loss. Continue drinking around indoor exercise and take breaks from heavy layers. If you have heart, kidney, or liver disease, or have been told to limit fluids, ask your clinician how much is appropriate. Check whether urine is becoming lighter and more frequent, while remembering that urine colour can also change for other reasons.

Seek urgent help for confusion, fainting, severe weakness, inability to keep fluids down, or very little urine. Prompt assessment is also sensible when dizziness persists after drinking, diarrhoea or vomiting continues, or you have severe abdominal or side pain. A clinician can assess hydration and look for another problem, such as a urinary infection or a kidney stone.

Ask whether a medicine, illness, or fluid restriction could be affecting your hydration. You can also ask which drinks are suitable during vomiting or diarrhoea and which symptoms should prompt same-day assessment.