What should you know about dark concentrated urine?

Dark concentrated urine often reflects a higher concentration of waste products when you have not taken in enough fluid, but persistent or unusual colour can need medical assessment. Urine may look deep yellow or amber after sweating, vomiting, diarrhoea, fever, exercise or a long period without drinking. Medicines, supplements and some foods can also alter its shade. The colour alone cannot identify the cause.

Concentrated urine is commonly darker and stronger-smelling because it contains less water. It often becomes lighter after regular drinking and rest. Brown, tea-coloured or cola-coloured urine is different from ordinary deep yellow urine and may reflect bile-related illness, blood or muscle breakdown. Cloudiness, a red or pink tinge, burning, frequent urination, side or back pain, fever, yellow skin or pale stools add useful clues. Dark urine can occur with dehydration or heat exhaustion, while hepatitis A and hepatitis B can also cause dark urine alongside symptoms such as tiredness, nausea or yellowing of the eyes.

If you otherwise feel well, drink fluids regularly and avoid waiting until you are very thirsty. Small, frequent drinks may be easier if you feel nauseated. Replace fluids after sweating or an illness with vomiting or diarrhoea; a pharmacist or clinician can advise whether an oral rehydration solution is suitable. Check whether a newly started medicine, vitamin or supplement can change urine colour, and do not stop prescribed treatment without advice. Notice whether the urine becomes lighter and whether any new symptoms appear.

Arrange medical advice if dark urine continues despite drinking, keeps returning without an obvious explanation, or is brown, tea-coloured, red or pink. Seek prompt care for yellow eyes or skin, severe abdominal or side pain, fever, confusion, fainting, marked weakness, very little urine, or inability to keep fluids down. After heavy heat exposure, urgent assessment is needed for confusion, collapse, worsening weakness or muscle pain with unusually dark urine. A clinician may ask about fluid loss, medicines and recent activity, examine you, and test a urine sample or blood if needed.

You could ask: What urine colours or associated symptoms make this more urgent? Could my recent illness, heat exposure, medicine or supplement explain the change? Do I need a urine test or blood tests? How much should I drink while I recover, considering any kidney, heart or liver condition?