Signs of Dehydration in Babies
A baby can lose fluid faster than you expect. Vomiting, diarrhea, or a fever can tip the balance in hours.
Dehydration means your baby's body has lost more fluid than it has taken in. In infants it can move quickly, so the signs are worth knowing before you need them. This page covers what to watch for, what causes it, what to do, and the points where you stop watching and call. The clearest everyday signal is wet diapers: count them. Most other signs build on that one.
Reviewed against current AAP, CDC and federal guidance
Signs by severity
- Fewer wet diapers — fewer than six in a day
- Darker urine than usual
- Dry, parched mouth
- Fewer tears when crying
- Fussier than usual, or playing less than usual
- A soft spot on the head that looks slightly sunken
At this stage the main job is fluid in. Keep feeding on demand and keep counting diapers. If signs hold steady or improve over the next few hours, you are likely on the right track. If they build, move to the next column.
- Urinating only one to two times a day, or much longer gaps than usual between wet diapers
- A clearly sunken soft spot on the head
- Sunken eyes
- No tears when crying
- Very sleepy, drowsy, or hard to rouse
- Cool, discolored, or blotchy hands and feet
- Wrinkled skin
- Fast breathing or a racing heartbeat
These are not wait-and-see signs. Severe dehydration can affect circulation. Call your pediatrician or seek urgent care. See the emergency and call-now blocks below for the exact lines.
Wet diaper decoder
| What you see | What it suggests | What to do |
|---|---|---|
| Six or more wet diapers a day, pale urine | Hydration is holding | Keep feeding as usual |
| Fewer than six wet diapers a day, darker urine | Early dehydration possible | Feed more often, watch the next few hours |
| No wet diaper for 3 or more hours, alongside other signs | Concerning fluid loss | Call your pediatrician |
| Only one to two wet diapers all day | Severe dehydration possible | Seek urgent care; call your pediatrician |
What causes it
- Vomiting — fluid is lost and feeds do not stay down
- Diarrhea — often the biggest fluid loss, and it can be steady
- Fever — raises fluid needs and can reduce appetite
- Poor feeding — a baby who is too sick, congested, or sleepy to feed well
- Heat — hot weather or overdressing increases fluid loss
What to do
- Breastfeeding: keep nursing, and offer more often than usual
- Formula: keep offering formula; do not water it down
- If your baby is vomiting, try smaller amounts more frequently
- Do not stop milk feeds during a stomach bug unless your pediatrician tells you to
Breast milk and formula carry the fluid, salts, and calories a sick baby needs. The AAP advice for diarrhea is to keep giving breast milk, formula, or cow's milk; check with your pediatrician if your baby seems bloated or gassy afterward.
- A commercial oral electrolyte (rehydration) solution can help replace fluid and salts
- Use a store-brand or name-brand product; the AAP says not to mix your own at home
- Ask your pediatrician which product and how much before you start
- Give it in small amounts, frequently, alongside milk feeds
The AAP says to give electrolyte solution in small amounts and to ask your pediatrician which one. Use commercially made solutions rather than homemade, and do not guess the volume on your own.
- No plain water as the main fluid for a young infant — it is very low in salt and can be unsafe in large amounts
- No juice, soda, soup, sports drinks, or boiled milk — the AAP notes these have the wrong amounts of sugar and salt and may make a sick baby worse
- No over-the-counter anti-vomiting or anti-diarrhea medicine unless your pediatrician prescribes it for this illness
These drinks can pull more fluid into the gut or upset the salt balance, which makes dehydration worse, not better.
Call your pediatrician now
- A drop in wet diapers — no wet diaper for 3 or more hours alongside other signs, or much longer gaps than usual
- Any sign of dehydration: sunken soft spot, sunken eyes, no tears, very dry mouth, very few wet diapers
- Cannot keep any clear liquids or feeds down
- Vomiting that lasts more than 12 to 24 hours
- Vomit that looks green, bloody, or like coffee grounds
- Diarrhea with blood, or symptoms that get worse rather than better
- Will not eat or drink, or a belly that looks swollen
- Any fever in a baby under 3 months (this always warrants a call)
Get emergency care
- Too weak, limp, or sleepy to wake or feed
- No urine output at all, on top of other dehydration signs
- Cool, blotchy, or grayish hands, feet, or skin
- Fast or labored breathing, or a racing heartbeat
- Unresponsive, fainting, or a noticeable change in alertness
A simple way to track it
- Mark each wet diaper with a time
- Note feeds offered and whether they stayed down
- Watch the soft spot, eyes, tears, and energy level
- Trust a clear downward trend over any single reading
Quick answers
- How many hours without a wet diaper is too long for a baby?
- Watch the trend closely once diapers drop below about six a day. MedlinePlus flags no wet diaper for 3 hours or more, alongside other signs, as a marker of dehydration in babies and young children — that is a reason to call your pediatrician. The fewer the wet diapers and the longer the gap, the more urgent it is. Only one to two wet diapers in a whole day points toward severe dehydration and urgent care.
- What does a sunken soft spot mean?
- The soft spot (fontanelle) is the soft area on top of a baby's head. When a baby is dehydrated it can look sunken or depressed rather than flat. The American Academy of Pediatrics lists a sunken soft spot among signs of dehydration in infants and toddlers. A clearly sunken soft spot, especially with sunken eyes, no tears, or very few wet diapers, means you should seek care promptly.
- Can I give my baby water if they seem dehydrated?
- For a young infant, no — plain water should not be the main fluid, because it is very low in salt and can be unsafe in larger amounts. Keep giving breast milk or formula, which carry fluid, salts, and calories. If extra fluid is needed, a commercial oral electrolyte (rehydration) solution may help, but ask your pediatrician which one and how much before starting. The AAP also advises avoiding juice, soda, soup, sports drinks, and boiled milk, which have the wrong amounts of sugar and salt.
- My baby is vomiting and can't keep feeds down. What should I do?
- Try smaller amounts more often rather than a full feed at once. Keep offering breast milk or formula; your pediatrician may suggest small, frequent amounts of an electrolyte solution between feeds. Call your pediatrician if your baby cannot keep any clear liquids down, if vomiting lasts more than 12 to 24 hours, or if you see signs of dehydration such as a sunken soft spot, no tears, very few wet diapers, or unusual sleepiness. Green, bloody, or coffee-ground vomit needs a call right away.
- What is the difference between mild and severe dehydration in a baby?
- Mild to moderate dehydration shows as fewer than six wet diapers a day, darker urine, a dry mouth, fewer tears, fussiness or playing less, and a slightly sunken soft spot — signs to feed more and watch closely. Severe dehydration adds a clearly sunken soft spot, sunken eyes, no tears, very few wet diapers (only one to two a day), cool or blotchy hands and feet, wrinkled skin, and a baby who is very sleepy or hard to rouse. Severe signs mean urgent care, not wait-and-see.
Sources & further reading
Keep temps, symptoms, and meds in one place.
ParentFlow logs your baby's health in one calm place to share with your pediatrician.
App Store Google Play Open Web AppThis guide reflects current AAP, CDC and federal guidance and is for educational purposes only. It does not constitute medical or legal advice. ParentFlow is a wellness companion — not a substitute for your pediatrician. For any medical concern, contact your healthcare provider.