What should you know about flu dehydration?

A high temperature and sweating increase fluid loss, while nausea, sore throat, fatigue or vomiting can make drinking difficult. Diarrhoea can add further loss. Signs may include thirst, dry mouth, headache, tiredness, dizziness, passing urine less often, or dark urine. Dehydration can make flu symptoms feel more intense and can increase weakness when you stand.

The pattern matters. Dark urine may occur with dehydration, but urine changes can also have other causes. Persistent vomiting or diarrhoea, kidney problems, and medicines that affect fluid balance can raise concern and deserve tailored advice.

Take frequent small sips rather than waiting until you feel very thirsty. Water, clear soups and oral rehydration drinks can help; if vomiting occurs, pause briefly and restart with smaller sips. Eat light foods when able. Keep track of how often you urinate and whether your mouth, energy and dizziness improve.

Do not force large amounts quickly if you are nauseated. People with kidney, heart or other conditions affecting fluid intake should ask a clinician how much to drink. Avoid relying on alcohol while recovering because it can worsen fluid loss.

Seek urgent care if you are confused, faint, unusually drowsy, unable to keep fluids down, breathing rapidly, or passing very little urine. Contact a clinician promptly if dehydration signs are worsening, fever persists, or you have repeated vomiting or diarrhoea. Children, older adults and people with long-term conditions may become dehydrated more quickly.

Could my symptoms be dehydration or another illness? Is an oral rehydration drink appropriate for me? Do my medicines or medical conditions change my fluid plan? Which urine or dizziness changes need urgent help?