What should you know about over dehydration?

Fluid loss may follow vomiting, diarrhoea, fever, heavy sweating, heat exposure, or difficulty drinking. Thirst, dry mouth, dark urine, headache, tiredness, dizziness, and constipation can occur. Cloudy or dark urine has other possible causes too, so urine colour alone cannot diagnose dehydration.

People with kidney, heart, or liver conditions may need individual fluid advice. Drinking very large amounts quickly is not a safer substitute for balanced replacement and can disturb the body’s salts.

Rest somewhere cool and take frequent small sips. An oral rehydration solution can replace water and salts lost through vomiting or diarrhoea; prepare it exactly as directed. Continue breastfeeding where relevant, and return to light meals as nausea settles.

Avoid relying on alcohol. Ask a clinician or pharmacist about the right plan if you take water tablets, have a fluid restriction, or cannot keep drinks down. Monitor whether urination becomes more regular and your alertness improves.

Get urgent help for confusion, fainting, severe weakness, inability to drink, very little urine, a fast or irregular heartbeat, severe abdominal pain, or bloody vomit or stool. Heat-related illness with hot skin, collapse, or altered behaviour needs emergency attention.

Seek medical advice if symptoms follow persistent vomiting or diarrhoea, or if you have signs of a urinary infection or kidney stone such as fever, painful urination, or severe side pain. Children and older adults can worsen quickly.

Ask how much and what type of fluid is suitable for you, whether medicines need adjustment, and whether testing is needed for salts, kidney function, infection, or another cause of your symptoms.