Adults usually take in 2 to 3 quarts of water a day in fluids and foods; dehydration results when the loss of water caused by illness, overexertion, extreme heat, or medication exceeds the intake. The very young and very old are most susceptible. Dehydration can lead to shock and can be fatal.
Symptoms of severe dehydration are a dry mouth, coated tongue, thick saliva, a pinched look in the face, lethargy, irritability, sunken eyeballs, pallor, and low urine output.
Vomiting or diarrhea or both can lead to dehydration in an adult if the condition continues more than 24 hours. An infant under 3 months of age who has three copious, loose bowel movements within a 6-hour period or who vomits up all feedings in a 6 hour span may be dehydrated. Telephone the doctor for advice. With an older baby who has loose stools and vomiting, you can wait up to 24 hours before telephoning the doctor; give the child the diarrhea diet in the meantime.
Get medical advice, too, if a child or adult cannot replace lost water by drinking because they vomit up anything they swallow. Lost fluids may have to be replaced intravenously.
Excessive water loss from sweating in high heat or during exercise can result in dehydration. Strenuous physical activity in very hot weather can lead also to muscle cramps because salt as well as water is lost in perspiration. Drinking a glass of salted water (1 teaspoon salt to 1 quart water) may relieve the cramps; the dehydrated person should also drink plain water, juice, tea, or other liquids, but not alcoholic beverages.
If you are taking certain medications-for example, a diuretic-discuss with your doctor changing the regimen during hot weather.