What should you know about morning urine very dark?

Urine normally becomes more concentrated overnight, so a darker yellow first sample may become lighter after drinking. Dark urine can also follow sweating, vomiting, diarrhoea, fever, or limited fluid intake; dehydration and heat exhaustion are possible concerns. Brown urine, pale stools, yellowing of the eyes, or itching can point to a liver or bile problem such as hepatitis. Red or cola-coloured urine may reflect blood or muscle breakdown and should not be dismissed. Food, medicines, and supplements can change urine colour too.

Drink fluids normally during the day and observe whether the colour returns towards pale yellow. Do not force large amounts of water if you have been told to restrict fluids. Note any burning, pain, unusual smell, fever, new medicine, strenuous exercise, or change in bowel or skin colour. If the colour remains dark after hydration, arrange a clinical assessment; a urine sample and other tests can help identify the cause.

Seek urgent medical help for very dark urine with severe side or abdominal pain, inability to keep fluids down, confusion, fainting, marked weakness, or very little urine. Prompt assessment is also needed for visible blood, yellow skin or eyes, fever with worsening illness, or dark urine that keeps recurring. A clinician can decide whether dehydration, infection, bleeding, liver disease, or another explanation needs treatment.

Could my medicines, supplements, fluid intake, or recent illness explain the colour? Should I provide a urine sample or have liver and kidney tests? Which changes would mean I should seek urgent help?