What should you know about dark yellow in urine?

Urine colour can become deeper after sweating, exercise, vomiting or diarrhoea. Some supplements, especially those containing B vitamins, can also make urine look bright or yellow. Colour alone cannot identify the cause, so notice whether the change settles after drinking fluids and whether other symptoms are present.

Dehydration commonly causes concentrated, dark yellow urine, often alongside thirst, a dry mouth, headache or passing urine less often. Heat exposure and heavy sweating can increase fluid loss; heat exhaustion may also cause weakness, dizziness, nausea and heavy sweating.

Dark yellow urine may be harmless when it is an isolated, short-lived change. Brown, tea-coloured or orange urine can have different causes, including bile-related problems. Hepatitis A and hepatitis B can present with dark urine together with yellowing of the skin or eyes, pale stools, unusual tiredness, nausea or discomfort under the ribs.

Drink fluids regularly, taking small sips if you feel sick. If you have been sweating heavily or losing fluid through vomiting or diarrhoea, an oral rehydration solution may help replace water and salts; follow the product instructions. Rest somewhere cool if heat played a part.

Check the colour again after rehydrating and note any medicines or supplements taken recently. Do not force large amounts of fluid if you have been told to restrict fluids because of a heart or kidney condition. Arrange a clinical review if the colour stays dark, keeps returning, or comes with urinary symptoms such as burning, urgency, blood or pain.

Seek urgent medical help if dark urine occurs with confusion, fainting, severe weakness, inability to keep fluids down, very little urine, severe abdominal pain, or signs of serious heat illness such as hot skin and altered alertness.

Contact a clinician promptly for tea-coloured or brown urine, yellow skin or eyes, pale stools, fever, repeated vomiting, swelling, or visible blood. These features can point to liver, kidney, urinary or heat-related problems that need an examination and possibly urine or blood tests.

Ask whether your urine colour fits dehydration or could relate to a medicine, supplement, liver problem or urinary condition. Tell the clinician when the change began, how often you urinate, how much you have been drinking, recent heat exposure, and whether pain, fever, nausea, jaundice or blood is present.