Dark urine while drinking lots of water: what to know

Large fluid intake does not prevent urine from looking dark when the body is losing fluid through sweat, diarrhoea or vomiting. Colour can also come from vitamins, medicines or food pigments. If the urine is brown, tea-coloured or cola-coloured, the pigment may come from bile, blood or muscle rather than water balance. Kidney or urinary problems may cause pain, burning, blood or a change in output. A clinician needs the wider pattern to tell these possibilities apart.

Do not keep increasing water intake simply to make urine clear. Drink normally, replace ongoing losses sensibly, and follow any fluid limit given for a heart or kidney condition. Check recent supplements, medicines, foods and strenuous exercise. Note whether the urine changes at different times and whether you have pain, fever or reduced output. Book a medical review if the change persists despite your usual intake.

Urgent care is needed for almost no urine, confusion, fainting, severe weakness, severe muscle pain or inability to keep fluids down. Seek prompt medical review for visible blood, brown urine, yellow skin or eyes, fever with back or side pain, or burning urination. Urine and blood tests may be needed to identify the source.

Ask whether your fluid intake is appropriate for your health, whether a medicine or supplement may be changing the shade, and which tests could distinguish blood, infection, liver-related pigment or muscle pigment. Share any fluid losses and changes in urine amount.