Red eyes and dehydration: what should you know?

When the body loses more fluid than it replaces, the tear film may become less comfortable and blinking can feel scratchy. Dry mouth, thirst, dark urine, passing urine less often, dizziness or unusual tiredness may support dehydration. Fluid loss can follow vomiting or diarrhoea with gastroenteritis, heavy sweating during heat exhaustion, or another illness. Redness may instead come from allergy, infection, contact lenses, smoke or rubbing. The eye appearance cannot identify the source of fluid loss by itself.

Sip fluids regularly and choose an oral rehydration solution when vomiting, diarrhoea or substantial sweating makes replacing fluid and salts difficult. Rest in a cool place after heat exposure, and avoid alcohol while recovering. Do not force large amounts at once if you feel nauseated. Remove contact lenses if the eyes are dry or red, and use a cool compress for comfort. If urine remains dark, dizziness continues or you cannot keep fluids down, contact a clinician for guidance.

Seek urgent medical help for confusion, fainting, severe weakness, inability to drink, very little urine, or worsening dizziness. Eye pain, strong light sensitivity, blurred or reduced vision, injury or marked swelling also needs prompt eye assessment. Arrange medical advice when dehydration symptoms do not improve with fluids, or when diarrhoea, vomiting or heat-related symptoms continue.

Could dehydration explain my eye dryness and other symptoms? Which rehydration drink is suitable for me? Do my medicines, kidney history or eye condition change how I should replace fluids?