What are the signs of dehydration in adults?
Early signs of dehydration in adults are thirst, dark scant urine, dry mouth, headache and fatigue. That is the routine end of a hot day. Advancing: dizziness on standing, racing heart, confusion, and skin that tents when pinched; in older adults, new confusion is often the loudest sign.
During illness, oral rehydration solution replaces what vomiting and diarrhea actually take, salts as well as water, and beats plain water and sports drinks.
Inability to keep any fluid down for a day, barely any urine, or confusion tips into needing medical care, faster in the very young, very old, diabetic or kidney-impaired.
Source: NHS, dehydration
See a doctor promptly if
- Confusion, headache, vomiting or seizure after drinking large volumes of plain water during heavy exertion: possible low blood sodium, a medical emergency
- Passing very little or no urine for several hours, dizziness on standing, or a fast weak pulse
- Sudden unexplained thirst with frequent urination and weight loss. This pattern needs a diabetes check, not more water
How to tell how dehydrated you are
| Result | In short | What it means |
|---|---|---|
| Thirsty, urine a darker yellow | Mild | The earliest and most reliable pair. Drinking to a pale straw color fixes it within a couple of hours. |
| Dry mouth, headache, tired, less urine | Mild to moderate | Still treatable at home with fluid taken steadily rather than all at once. Add salt and sugar if the cause is vomiting or diarrhea. |
| Dizzy on standing, no urine for 8 hours, sunken eyes | Moderate | Oral rehydration salts rather than water alone, and a call to a doctor if it does not turn around in a few hours. |
| Confused, racing pulse, cold hands, no tears | Severe | Emergency. This is a circulation problem now, not a thirst problem, and it needs fluid given by a drip. |
| In a baby or an older adult | Lower the threshold | Both dehydrate faster and show it later. A sunken soft spot, no wet diaper for six hours, or new confusion in an older person all mean today, not tomorrow. |
Signs overlap, and people slide between bands quickly. Treat the worst sign you have, not the average. Check it against the guidelines.
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Answered by the AskDoc Medical Team · Medically reviewed under our Medical Director, MBBS · How we review
For vomiting or diarrhea
Rehydration salts replace fluid better than water or sports drinks. Keep a few sachets at home; nobody wants to shop for them while sick.
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