What should you know about dark urine at night?

During sleep, you usually go several hours without drinking, so the first urine after waking can be deeper yellow. Sweating, exercise, a warm room, vomiting, or diarrhoea can make this concentration more noticeable. Brown, cola-coloured, red, or tea-coloured urine is different from ordinary deep yellow urine and may reflect blood, bile pigments, muscle breakdown, medicines, or another condition. The timing alone cannot identify the cause.

Compare the first urine with later samples after normal fluid intake, and record the shade, smell, frequency, pain, and any change in urine amount. Drink regularly during the day unless you have been given a fluid restriction. Review medicines and supplements with a clinician rather than stopping them yourself. Arrange an appointment if the colour remains dark, appears during the day, recurs, or comes with burning, fever, swelling, yellowing, or unusual tiredness.

Seek urgent help for inability to pass urine, severe pain, fever with chills, confusion, faintness, repeated vomiting, very little urine, or red or brown urine with clots. Prompt assessment is also sensible when dark urine follows intense exertion with muscle pain or weakness, because the combination can signal a problem needing treatment.

Ask whether a urine sample is needed, how much fluid is suitable for you, and whether your medicines, supplements, exercise, or recent illness could explain the colour. Tell the clinician whether the change is limited to overnight or continues through the day.