Overview

Dehydration in infants (3-12 months): Causes and signs

Dehydration — a condition in which the body loses more fluid than it takes in. In infants, because of their physiological characteristics, this condition can develop very quickly and pose a serious health risk. It is the most common complication of any illnesses accompanied by vomiting, diarrhea or high fever.

Why do infants become dehydrated faster?

Children in the first year of life are in a high‑risk group for several reasons:

High metabolism: Their metabolic rate is considerably more intense than that of adults, requiring a larger fluid turnover.
Larger body surface area: Relative to their mass, infants have a larger skin surface, through which more fluid is lost via sweating and breathing.
Immature kidneys: The kidneys are not yet able to concentrate urine as efficiently as in adults.

Key signs of dehydration

It is critically important for parents to recognize the early signs of dehydration in order to act promptly. These include:

Reduced urine output: This is the earliest and most reliable indicator. A dry diaper for 6–8 hours is a warning sign.
Dry mucous membranes: Dry lips, tongue, crying without tears.
Sunken eyes and sunken fontanelle: Signs of more severe dehydration.
Lethargy and sleepiness: The child becomes apathetic and difficult to awaken.

When these signs appear, start active rehydration of the child and consult a physician. For general mechanisms, read the article "Dehydration".

Dehydration in infants

Overview