What should you know about dehydration yellow urine?

Urine contains water and waste products. When less water is available, the urine can look more concentrated and turn a deeper yellow. Morning urine may also be darker because you have gone several hours without drinking. Vitamins, foods and some medicines can change urine colour, so a yellow shade does not automatically mean dehydration.

Thirst, dry mouth, headache, tiredness, dizziness and passing urine less often support the possibility of fluid loss. Cloudy urine, burning, fever, pain in the side, or blood in the urine suggests a different problem may need attention. Dark urine with yellowing of the eyes or skin also warrants medical advice.

Drink small amounts regularly and continue until thirst and other mild symptoms settle. Replace fluids lost through sweating, vomiting or diarrhoea; an oral rehydration solution may be useful during significant fluid loss. Keep a simple record of how often you urinate and whether the colour changes. Avoid using urine colour as the only measure if you take supplements or have a medical condition that affects fluid balance.

If fluid restriction has been prescribed for heart or kidney disease, ask your clinician for an individual plan. Read more about Dehydration and Dark Urine for related guidance.

Get urgent help if you are confused, faint, extremely weak, unable to keep fluids down, or passing very little urine. Seek prompt assessment for blood in urine, severe side or abdominal pain, fever with urinary symptoms, or yellow skin or eyes. Arrange a review if urine stays unusually dark despite drinking suitable fluids.

Could my urine colour be caused by dehydration, a supplement or a medicine? How much fluid is appropriate for me? Do my urinary symptoms suggest infection or a kidney problem? Should my urine or blood be tested if the colour does not return to its usual shade?