Dehydration

What is dehydration?

Dehydration happens when your body loses more fluids than it takes in. If it is not treated, it can become serious.

Symptoms

• Feeling thirsty
• Headache
• Feeling dizzy or faint
• Dark yellow urine
• Dry lips and tongue

Causes

• Have been ill with vomiting or diarrhoea
• Have spent too long in the sun
• Sweat heavily
• Have a high temperature
• Are diabetic

The NHS recommends that you call 999 if you or somebody else has signs of dehydration and:

• blue, grey, pale or blotchy skin, lips or tongue – on brown or black skin, this may be easier to see on the palms of the hands or soles of the feet
• skin that feels cold
• difficulty breathing, or is taking lots of quick breaths
• are confused
• are sleepier than normal or difficult to wake

These could be signs of shock, which is a serious complication of dehydration.

Please note – The content on this website is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you are feeling unwell, make an appointment to see your GP or contact NHS 111. In an emergency, dial 999.

Last updated: July 31, 2026