Dehydration
Dehydration occurs when the body loses more fluid than it takes in. Young children, older adults, and people with ongoing vomiting or diarrhea are at higher risk.
About dehydration
Dehydration occurs when the body loses more fluid than it takes in. Young children, older adults, and people with ongoing vomiting or diarrhea are at higher risk.
What can cause it?
Dehydration follows vomiting, diarrhea, fever, sweating, heat, poor intake, excess urination, or certain medicines.
Infants, older adults, and people with chronic disease can worsen quickly.
What a patient may notice
Symptoms vary from person to person. Possible signs may include:
- Thirst, dry mouth, or reduced urination
- Dark urine, dizziness, weakness, or headache
- In children: fewer wet diapers, no tears, or unusual sleepiness
How clinicians find the cause
A clinician assesses vital signs, mouth moisture, urine output, weight change, alertness, and circulation. Blood or urine tests measure electrolytes and kidney function when dehydration is moderate or severe.
Treatment and next steps
- 1
Mild dehydration is treated with frequent oral rehydration solution.
- 2
IV fluids are used when the patient cannot drink, has shock, severe electrolyte disturbance, or altered alertness.
- 3
The cause of fluid loss also requires treatment.
Supporting recovery
- Use small frequent sips and an oral rehydration product for significant diarrhea or vomiting.
- Monitor urine output and avoid alcohol or excess caffeine.
What to expect
Mild dehydration often improves with timely oral rehydration and treatment of the fluid-loss cause. Infants, older adults, and people with kidney, heart, or other chronic conditions can deteriorate quickly and may need supervised fluid replacement. Severe dehydration is life-threatening but is often reversible with urgent treatment.
Possible complications
- Electrolyte disturbances that can cause weakness, confusion, seizures, or abnormal heart rhythms
- Kidney injury, very low blood pressure, heat injury, or shock
- Falls, loss of consciousness, organ injury, or death when severe dehydration is not treated
When to Contact a Medical Professional
A same-day medical evaluation is recommended, especially when symptoms are severe, worsening, or accompanied by fever, vomiting, weakness, or significant pain.
Emergency care is needed for fainting, confusion, inability to drink, no urination, very fast heartbeat, seizure, or a person who is difficult to wake.Get emergency help for severe trouble breathing, new chest pressure, fainting, seizure, sudden weakness on one side, uncontrolled bleeding, blue or gray lips, or a person who is difficult to wake.
Ways to lower risk
- Drink before and during heat or exercise and increase fluids during illness as medically appropriate.
- Use early oral rehydration for vomiting or diarrhea.
Trusted health information
This CHS patient-education page uses original wording and links to MedlinePlus for additional information.