Diarrhea and dehydration—and why they matter

Diarrhea is the term used to describe loose, watery stools. Most babies have the occasional loose bowel movement, which is normal and is seldom a cause for concern. But if there’s a sudden increase in loose bowel movements or your baby’s stool suddenly becomes larger, looser, and more frequent, she may have diarrhea. 

How to know when your baby has diarrhea

It can be hard to tell if a baby has diarrhea, especially for exclusively breastfed babies. However, without solid foods, normal breastfed poop resembles diarrhea because it’s watery.

The key to identifying diarrhea is recognizing changes in your baby’s stool pattern: If the number or size of stools your baby typically has each day doubles or the consistency changes, becoming looser and more watery, your baby may have diarrhea.

Causes and prevention of diarrhea

Diarrhea can be caused by something diet related, such as food sensitivity or allergy. Or it can be caused by an intestinal infection like a virus, bacteria, or parasite; a food allergy; or food poisoning. 

Avoid serving the offending foods if your child has food sensitivities or allergies. And wash your and your baby’s hands frequently to avoid contracting infections.

What to do about diarrhea

If your child has mild diarrhea, she can most likely continue to eat and drink normally and should be diarrhea-free within a couple of days. Breastfed babies should continue to breastfeed. But if your baby is formula fed or has been weaned to cow’s milk and seems bloated or gassy, your pediatrician may suggest a temporary change in diet.

If your child is eating solids, you may feed him smaller amounts of food and offer bland and easy foods on the stomach. Most pediatricians recommend the BRAT diet (bananas, rice, applesauce, and toast) to make the stools more solid.

The American Academy of Pediatrics (AAP) notes that electrolyte solutions are usually unnecessary for mild diarrhea bouts. Still, small amounts may be given to replace the water and salts lost during bouts of moderately severe diarrhea. The AAP warns against trying to prepare such fluids yourself. You can call your child's pediatrician to discuss appropriate amounts for their age level. Don’t give your child anti-diarrhea medicine unless your pediatrician recommends it, as it can have serious side effects for young children, especially those younger than age 2.

Dehydration as a result of diarrhea

Diarrhea can cause your baby to lose more fluid and electrolytes than she takes in, which can lead to dehydration. Dehydration can happen quickly—within a day or two—and can be very dangerous for babies, especially newborns. So if your baby does have diarrhea, it’s critical to watch for these signs of dehydration:

  • fewer wet and poopy diapers
  • blood or pus in your baby’s stools (which may be black, white, or red)
  • dry eyes, mouth, and tongue
  • sunken eyes and less elastic skin (slow to return to normal after being pinched)
  • sunken soft spots (fontanelles) on your baby’s head
  • body temperature more than 102°F or rectal temperature more than 100.4°F
  • loss of body weight

Also, watch for these changes in your baby’s behavior:

  • irritability
  • crying without tears
  • rapid breathing
  • drowsiness and weakness
  • vomiting
  • behavior indicating abdominal pain, like fussiness, squirming or tensing up muscles, or making faces that indicate pain, like grimacing or squeezing her eyes shut
  • loss of consciousness

What to do about dehydration

Call your child’s healthcare provider at the first sign of dehydration, especially if your child is younger than age six months. Your doctor may recommend an oral rehydration solution to replace lost fluid and electrolytes. But your baby may need a prescription, such as an antibiotic or an antiparasitic. Babies with moderate or severe dehydration may require intravenous (IV) fluids. Quick medical attention is critical since dehydration makes inserting IV needles into babies’ small veins increasingly difficult. 

It’s important to contact your healthcare provider before beginning any diarrhea treatment yourself. Anti-diarrhea medications, including those available over the counter, can have serious side effects. Also, don’t offer water to your baby. Giving too much water to a baby can cause a rare but serious condition known as hyponatremia, or “water intoxication,” in which too much water causes a dangerous electrolyte imbalance. Hyponatremia is one of the leading causes of seizures in infants. 

Learn more about babies’ poop here

Last updated December 6, 2021

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