​​​​Learn about signs that your baby may be ill, such as fever, irritability, and lethargy, and when to take your baby to a doctor.

Key points

  • Fever is usually a sign that your baby’s body is fighting an infection.
  • One of the first signs of illness in babies is a change in behaviour such as being lethargic or irritable.​
  • In newborn babies and young infants three months of age or under, fever may be the first and only sign of a serious infection.​

A change in behaviour is often a sign of illness in babies. If your baby is ill, they may cry more or have a change in activity level.

When to see a doctor

See your child’s doctor right away if you notice any of the following signs:

  • a fever (for babies 3 months old or younger)
  • crying inconsolably
  • listless or limp
  • having convulsions (seizures)
  • fontanelle, the soft spot at the top of their head, is starting to swell
  • pain
  • purple splotches on their skin, or another type of rash
  • pale or flushed
  • problems breathing
  • refusing to breastfeed or drink from a bottle
  • appears to have trouble swallowing
  • vomiting or has diarrhea

In newborn babies and young infants three months of age or under, fever may be the first and only sign of a serious infection. If you notice a temperature that is even just slightly above the normal range, bring your newborn baby to the doctor as soon as possible. A normal temperature is 38°C (101°F) taken rectally or 37.5°C (99.5°F) taken under the armpit.