What should you know about sudden dark brown urine?

Urine can become dark when you have lost fluid through sweating, vomiting, diarrhoea, or poor intake. It may lighten after drinking, but persistent brown colour needs review. Liver or bile-flow problems can cause dark urine, sometimes with yellow skin or eyes, pale stools, itching, nausea, or pain under the right ribs. Blood can make urine look tea-coloured or brown, while intense exercise or muscle injury can release pigment that also darkens urine. A urine sample helps distinguish these possibilities.

If you feel able to drink, take small, regular sips of water and note whether the colour changes. Avoid strenuous exercise until the cause is clearer. Arrange a same-day clinical assessment if the colour remains brown, returns, or occurs with reduced urination, burning, back pain, or unusual tiredness. Tell the clinician about new medicines, supplements, recent exercise, heat exposure, vomiting, diarrhoea, and any yellowing of the skin or eyes.

Seek urgent help for confusion, fainting, severe weakness, inability to keep fluids down, very little urine, severe abdominal or back pain, fever with shaking, or yellow skin with worsening illness. Emergency assessment is also appropriate after a major muscle injury or unusually intense exercise when urine is brown and muscles are painful or weak.

Ask whether you need urine testing, blood tests for kidney and liver function, or an examination for muscle injury. Mention when the change began, how much you have been drinking, and any associated pain, fever, rash, yellowing, or medication changes.