Persistent dark urine

Urine may look darker when it is concentrated after limited fluid intake, sweating or vomiting. Heat exhaustion can cause fluid loss and may come with weakness, dizziness, headache or nausea. Hepatitis A or hepatitis B can affect the liver and may cause dark urine with yellow eyes, pale stools, nausea or discomfort under the ribs. Food, supplements and medicines can also change urine colour. Colour alone cannot identify the cause, so persistent change warrants clinical review.

Notice whether the colour changes after drinking fluids and whether you are passing urine normally. Record its shade, smell and frequency, along with pain, burning, fever, vomiting, bowel changes or recent travel. Rest in a cool place after heavy sweating and seek advice before taking unfamiliar supplements. A clinician may check a urine sample and assess hydration and liver-related symptoms.

Seek urgent care for very little urine, inability to keep fluids down, confusion, fainting, severe weakness, severe abdominal or back pain, blood in the urine, or yellow skin and eyes. Prompt assessment is also needed with fever, painful urination or worsening symptoms.

Could dehydration explain the colour, or do I need urine and blood tests? Could a medicine or supplement be involved? Which changes should trigger urgent help?