What should you know about very dark brown urine?

Urine can become brown when it is highly concentrated after sweating, vomiting, diarrhoea or not drinking enough. Dark brown urine can also occur with some medicines or foods. Less commonly, bilirubin from a liver or bile-flow problem can darken urine; hepatitis can be accompanied by yellow skin or eyes, pale stools, nausea or unusual tiredness. Muscle injury may release pigment that makes urine tea-coloured, especially after strenuous activity, with muscle pain or weakness. The colour alone cannot identify the cause.

Think about when the change began, how much you have been drinking, recent heat exposure, exercise, illness, foods and new medicines or supplements. If you can drink normally and have no warning symptoms, take regular fluids and observe whether the colour lightens. Do not stop prescribed medicine without advice. Arrange a clinical review if the colour stays brown, returns repeatedly, or you have burning, pain, fever, reduced urine or swelling. A clinician may check a urine sample and blood tests.

Seek urgent medical care for brown urine with yellow eyes or skin, severe abdominal or back pain, fever with shaking chills, confusion, fainting, marked weakness, very little urine, or muscle pain after intense exertion. Heat exposure with dizziness, headache, nausea or heavy sweating can signal heat exhaustion and needs prompt attention. Blood-coloured urine, clots, or inability to pass urine also needs urgent assessment.

Ask: Could dehydration, a medicine, liver or muscle problem explain this colour? Do I need urine and blood tests? Which symptoms mean I should return urgently? Should I change fluids or pause any non-prescription supplement?