How common is dark urine in dehydration?

When the body has less fluid available, the kidneys conserve water and urine becomes more concentrated. This can make it look deep yellow or amber and may be accompanied by thirst, dry mouth, headache, dizziness, or passing less urine. First urine after sleep can also appear darker. Foods, supplements, medicines, blood, and liver or urinary problems can change urine colour as well.

If you can drink safely, take small, frequent sips of water or an oral rehydration drink and move to a cooler place if heat or activity contributed. Continue drinking over time rather than taking a large volume quickly. Replace fluids lost through sweating, vomiting, or diarrhoea. Speak with a clinician before changing your fluid intake if you have been told to limit fluids because of a heart, kidney, or liver condition.

Seek prompt care if you cannot keep fluids down, are passing very little urine, feel faint when standing, have ongoing vomiting or diarrhoea, or the dark colour persists despite drinking. Get urgent help for confusion, collapse, severe weakness, severe abdominal or back pain, or urine that looks red, brown, or like cola.

Ask whether dehydration is a likely contributor and whether your medicines, supplements, or medical conditions could affect urine colour. Mention recent heat exposure, exercise, vomiting, diarrhoea, pain on passing urine, and any yellowing of the eyes or skin.