Dehydration in Babies: Signs & When to Get Help | Parenting Hub
Babies dehydrate faster than adults. Here are the early and serious signs, and when to seek emergency care.
Babies dehydrate quickly during illness, hot weather or feeding problems. Knowing the signs — and acting early — can prevent an emergency.
Early signs
- Fewer wet nappies than usual (less than 6 in 24 hours)
- Dark, strong-smelling urine
- Dry lips and mouth
- Fewer tears when crying
- Baby more sleepy or fussy than usual
Serious signs — emergency
- Sunken soft spot (fontanelle)
- Sunken eyes
- No wet nappy in 8+ hours (or 12+ hours over 6 months)
- Cold, mottled hands and feet
- Floppy, hard to wake, very lethargic
- Skin that stays pinched when gently lifted
Common causes
- Gastro (vomiting and diarrhoea)
- Fever
- Hot weather without enough feeds
- Feeding difficulties in the first weeks
- Refusing feeds with illness
What to do
For breastfed babies: feed little and often (every 20–30 minutes). For formula-fed: small frequent amounts. Don't give water to babies under 6 months. Oral rehydration solution (Hydralyte) is for gastro, on GP advice. Seek same-day GP care for early signs; call 000 or go to ED for any serious sign.
When to seek help
- Sunken fontanelle or eyes
- No wet nappy for 8+ hours
- Floppy, drowsy or unrousable baby
- Cold or mottled limbs
- Repeated vomiting with no fluids tolerated
Common questions
Can I give my baby water in hot weather?
Under 6 months: no — extra breast/formula feeds only. Over 6 months: small sips of cooled boiled water are fine alongside milk feeds.
How quickly can a baby become dehydrated?
With gastro, in just a few hours. Don't 'wait and see' if vomiting or diarrhoea is frequent — call your GP or nurse line.