What should you know about extremely dark urine?

Urine may look deep yellow or amber when fluid intake is low, especially after sweating, vomiting or diarrhoea. Food, supplements and medicines can also change colour. Brown, tea-coloured or cola-coloured urine is more concerning when it persists or appears with pain, illness, yellowing of the skin or eyes, or reduced urine output.

Dehydration and heat exhaustion can concentrate urine and may occur with thirst, headache, dizziness, weakness or heavy sweating. Liver or bile-flow problems can cause dark urine with pale stools, itching or jaundice; hepatitis A and hepatitis B are among conditions a clinician may consider when these features occur.

Blood, muscle pigments, infection or a medicine reaction can also alter urine colour. Colour alone cannot identify the cause, and a urine sample or blood tests may be needed.

If you feel well and the change followed sweating or limited fluids, sip water regularly and observe whether the urine becomes lighter. Avoid strenuous activity while unwell, and note any new medicines, supplements, foods or symptoms.

Arrange medical advice if the colour remains unusually dark, returns without an obvious explanation, or occurs with pain, fever, burning, nausea, pale stools, yellow skin or eyes, or changes in urine amount. A clinician can decide whether testing is needed.

Seek urgent care for confusion, fainting, severe dizziness, inability to keep fluids down, very little urine, severe abdominal or back pain, yellowing with marked illness, or dark urine after intense exertion with muscle pain or weakness. These combinations can signal significant dehydration or another condition needing prompt treatment.

What colour and duration should concern me? Could my medicines, diet or fluid loss explain it? Do I need urine and blood tests? Which warning signs mean I should attend urgent care?