The most important step when your baby has diarrhea is replacing lost fluids, not stopping the diarrhea itself. Most cases in babies are caused by viral infections and resolve on their own within a few days. Your job is to keep your baby hydrated, continue feeding, and watch for signs that things are getting worse.
Start With Fluids Right Away
Dehydration is the real danger with baby diarrhea, not the diarrhea itself. An oral rehydration solution (sold as Pedialyte or store-brand equivalents) is the best way to replace both the water and the electrolytes your baby is losing. For mild dehydration, the general guideline is about 50 milliliters per kilogram of body weight over four hours. For moderate dehydration, that doubles to 100 milliliters per kilogram. After each loose stool, offer an additional 10 milliliters per kilogram, up to about 240 milliliters.
For a 7-kilogram baby (around 15 pounds), that works out to roughly 350 milliliters (about 12 ounces) over four hours for mild dehydration, plus a few extra ounces after each watery diaper. Give it in small, frequent sips rather than large amounts at once, since a big volume can trigger more vomiting or loose stools.
Do not give your baby plain water, juice, sports drinks, or homemade sugar-salt mixtures. Plain water lacks electrolytes and can actually make things worse by diluting your baby’s sodium levels. Juice and sugary drinks can pull more water into the intestines and worsen diarrhea.
Keep Breastfeeding or Formula Feeding
If you’re breastfeeding, increase the frequency of feeds. Breast milk is an ideal rehydration fluid on its own, and the CDC notes that exclusive breastfeeding actually protects against certain types of diarrhea. You don’t need to replace breastfeeding with other fluids. Just nurse more often and for as long as your baby wants.
If your baby is formula-fed, continue with their regular formula at full strength. Older advice sometimes recommended diluting formula during diarrhea, but this is no longer recommended because it reduces the calories and nutrients your baby needs to recover. If diarrhea persists beyond a few days, your pediatrician may suggest temporarily switching to a soy-based or lactose-free formula, since the infection can temporarily reduce your baby’s ability to digest lactose.
For babies already eating solid foods, stick with simple, easy-to-digest options like bananas, rice cereal, applesauce, and toast. Avoid fatty or sugary foods. Most babies will have a reduced appetite during diarrhea, and that’s normal. Focus on fluids first, then offer small amounts of food when your baby seems interested.
How to Track Your Baby’s Hydration
Counting wet diapers is the simplest way to monitor whether your baby is getting enough fluid. From about six days old onward, a well-hydrated baby produces six to eight wet diapers per day. Fewer than six wet diapers in 24 hours, or going more than eight hours without a wet diaper, is an early warning sign of dehydration.
This gets tricky when diarrhea is mixed in with urine in the same diaper. Pay attention to the diaper’s overall weight and whether you can identify a urine component separate from the watery stool. Some parents find it helpful to place a small piece of tissue or cotton ball inside the diaper to detect urine independently.
Physical signs of dehydration to watch for include:
- Sunken fontanelle: the soft spot on top of your baby’s head dips inward instead of being flat or slightly curved
- Tearless crying: your baby cries but produces few or no tears
- Sunken eyes: the area around the eyes looks hollow or darker than usual
- Dry mouth and lips
- Unusual drowsiness or irritability: your baby is harder to wake or unusually fussy
Any of these signs, especially a sunken fontanelle or tearless crying, means your baby needs medical attention promptly.
Zinc Can Shorten Recovery
The World Health Organization recommends zinc supplementation during diarrhea episodes in children. For babies under six months, the dose is 10 milligrams per day. For older infants and children, it’s 20 milligrams per day, continued for 10 to 14 days even after the diarrhea stops. Zinc reduces the duration and severity of the episode and lowers the chance of recurrence in the following two to three months.
Zinc supplements for infants are available as dissolvable tablets or syrups. Talk to your pediatrician before starting zinc, particularly for very young babies, to confirm the right form and dose.
What Not to Give Your Baby
Over-the-counter anti-diarrheal medications like loperamide are not safe for infants and young children. These drugs work by slowing gut movement, which can cause dangerous side effects in babies, including bloating, intestinal blockage, and drowsiness. The goal is not to stop the diarrhea artificially but to support your baby’s hydration while the infection clears.
Antibiotics are also unnecessary for the vast majority of baby diarrhea cases, since most are caused by viruses (rotavirus and norovirus being the most common). Giving antibiotics for a viral infection won’t help and can actually worsen diarrhea by disrupting gut bacteria.
When Diarrhea Needs Medical Attention
For babies younger than 3 months, any diarrhea accompanied by a fever warrants an immediate call to your doctor. Young infants have less reserve to handle fluid losses and infections can escalate quickly at this age.
For babies older than 3 months, seek medical care if the diarrhea lasts more than 24 to 48 hours, or sooner if you notice any of these:
- Blood or black coloring in the stool
- Fever that won’t come down
- No wet diapers for several hours
- Severe belly pain (legs pulling up, inconsolable crying)
- Signs of dehydration like sunken eyes, dry mouth, or unusual sleepiness
- Vomiting so frequent that your baby can’t keep any fluids down
Bloody or mucus-filled stools can indicate a bacterial infection that may need specific treatment, so don’t wait on those. Similarly, if your baby becomes increasingly limp, unresponsive, or difficult to wake, that’s an emergency.
How Long Baby Diarrhea Typically Lasts
Viral diarrhea in babies usually runs its course in 5 to 7 days. The worst of it tends to hit in the first two to three days, then gradually improves. Stools may remain slightly looser than normal for a week or two after the infection clears, particularly in formula-fed babies, as the gut lining heals.
If diarrhea continues beyond two weeks, it’s considered persistent and may point to a food intolerance (commonly lactose or cow’s milk protein), a parasitic infection, or another underlying issue that needs evaluation. Your pediatrician can test the stool and adjust your baby’s diet to identify the cause.