When It Turns Serious

Most dehydration is mild, but it can cross into a medical emergency — and the signs look very different from a low afternoon. Watch for a racing heartbeat, dizziness or confusion, sunken eyes, and skin that stays pinched when you lift it.

A telling red flag is no urination for eight hours or more, or urine that is dark and barely there. At this stage, fluids alone may not be enough — it is time for medical help.

Older adults are especially vulnerable, because the thirst signal weakens with age, so they can fall behind without ever feeling thirsty. The same is true for young children, who lose fluid fast and cannot always say what is wrong.