When your baby is unwell, hot, or feeding less than usual, it's natural to worry about whether they're getting enough fluids. The good news: babies give us clear, watchable clues. This guide helps you read them calmly — and know exactly when to pick up the phone.
What dehydration looks like
Dehydration happens when a baby loses more fluid than they take in — often from vomiting, diarrhoea (loose nappies), a fever, hot weather, or simply feeding poorly while unwell. It can come on faster in tiny babies, so it's worth knowing the early signs.
Early, milder signs to keep an eye on:
- Fewer wet nappies — the most useful clue. Six or more well-soaked nappies in 24 hours is generally reassuring.
- Drier mouth and lips than usual.
- Fewer or no tears when crying.
- More tired or grizzly than their normal self.
- Urine that looks darker or more strongly scented.
The more urgent signs
These mean your baby needs to be seen promptly — call your GP, child-health nurse, or after-hours line, or go to an emergency department.
| Sign | What you might notice |
|---|---|
| Very few or no wet nappies | Dry nappies for many hours; a newborn with none for 6+ hours |
| Sunken fontanelle | The soft spot on top of the head looks dipped or hollow |
| Sunken eyes / no tears | Eyes look hollowed; crying without tears |
| Lethargy | Hard to wake, floppy, unusually still or unresponsive |
| Fast breathing or cold, mottled hands and feet | Skin looks blotchy; breathing quicker than usual |
Offering fluids and feeds
For most mildly unwell babies, the answer is simple: keep the milk flowing.
- Breastfed babies: offer the breast more often, even for short feeds. The Australian Breastfeeding Association and WHO both recommend continuing to breastfeed through illness — your milk gives fluids, energy and antibodies.
- Formula-fed babies: offer their usual formula, prepared as normal, in smaller, more frequent amounts if big feeds aren't going down.
- Small and often wins. A few minutes at the breast or small sips every 10–15 minutes is usually gentler than one large feed for a queasy tummy.
If your baby is feeding less
- Offer the breast or bottle little and often, rather than one big feed.
- Count and note wet nappies so you can see the trend over the day.
- For babies over about 6 months, you can also offer their usual water with meals.
- Only use oral rehydration solution if your doctor or pharmacist advises it — and not plain juice, soft drink or homemade mixes.
- Ring your GP, child-health nurse, or health line if signs aren't improving.
One important caveat: don't give extra water to a baby under 6 months unless a doctor has told you to — their fluids should come from breastmilk or formula, and too much water can be harmful.
When in doubt, ask
Dehydration in babies can change quickly, and you know your baby best. If you're unsure, it is always okay to call your GP, child-health nurse, or a parent health line — they would much rather hear from you early.
You're doing a wonderful job watching over your little one. Trust those instincts, keep the feeds coming, and reach out for help whenever your gut tells you to.