baby fever

The excitement a new baby brings is often accompanied by anxiety, as fresh challenges arrive every day. Take childhood illnesses, for example. When you’re dealing with a baby fever for the first time, it’s understandable to over-react, or feel stuck about not knowing what to do.

Your baby’s immune system is nowhere near as developed as your immune system, which means they’re much more likely to get ill. Their exposure to everyday germs means that even if you’re following all the hygiene recommendations, there will be times when your baby shows symptoms of being unwell1.

All babies cry, but what if your little one is fussing more than they usually do, or not eating as much as you want them to? If you’re uncertain about what’s normal or not, you’re far from alone. There’ll be times when you’ll want to know how to tell if you have a sick child, which is why we’ve written about spotting the most common signs of sickness in babies.

Common Signs of Baby Fever

Higher Temperature

With young babies, a fever is sometimes the first and only sign of serious infection2. It’s a good idea to have a baby thermometer at home to check your little one’s temperature when necessary.

If your baby’s temperature is even just a little raised, it’s very important for you to take them to a doctor immediately3 so they can help you manage the fever. In babies 6 months to a year old, a temperature of 37.2°C or higher, where the thermometer reading is taken from the armpit, suggests a baby fever. In adults and older children, a slightly higher reading (38°C) indicates a fever, but of course, it depends on where the reading is taken4.

If you’re wondering what to do when a baby has high fever, you should call your doctor if your toddler has a temperature of 38°C or higher. For older babies or young children, call your doctor if they have a temperature of 39°C or higher5.

A Drop in Your Baby’s Energy Levels

Young babies sleep a lot – around 13–14 hours for babies of 6-months-old6. If you find your baby is sleeping more than this, it may be a sign that they are not well.

Generally speaking, if your baby is alert when they’re awake, is eating well and can be comforted when they cry, it’s normal for there to be little differences in their activity level7. There are many possible causes for a change in your baby’s energy, but it’s sometimes quite difficult to spot when your baby’s levels drop because it can happen gradually, over time.

If you notice that your little one is sleepy, listless and doesn’t have energy, it could be a sign of a common infection like a cold. However, when accompanied by other symptoms such as a rash, or high temperature, lethargy could indicate something more serious, like the flu or even meningitis8. If you’re at all concerned, call your doctor, so they can assess the situation immediately and give your sick baby an examination if necessary.

More Noticeable Breathing

It won’t take more than a common cold (also known as an upper respiratory tract infection), to make the sound of your baby’s breathing a little more noticeable. An infection that affects your baby’s airwaves – often accompanied by other symptoms such as a runny nose, cough or sore throat – impacts how they breathe. Keeping your sick child well hydrated, and their bedroom well ventilated (sometimes with a cool-mist humidifier, to add moisture to the air) can be a good idea, as it can help to ease any congestion9.

Of course, if your baby is having considerable difficulty breathing, or you notice their symptoms are getting worse, always call your doctor.

Coughing, Difficulty Breathing, Pale Blue Skin

Coughs are as common as colds in babies, and often go hand in hand. Typically, you’ll be able to manage most childhood coughs at home, without having to visit the doctor, especially if you keep your baby well hydrated. However, keep an eye on any changes that indicate the cough is getting worse, causing shortness of breath. Difficulty breathing is often obvious if there is blueness around the lips or pale blue skin, and in these cases you should contact your doctor10 immediately.


If you’re noticing more watery poop in your baby’s diaper, this could be a sign that they have a viral or bacterial infection in their gut. While this is common, and you can usually look after your baby at home until they’re better, it’s important to make sure that they are getting enough liquid, as they’ll be losing a considerable amount when they have diarrhea.

At the first sign that your baby may be dehydrated (less pee in their diaper than usual, a dry mouth or sunken eyes)11 call your doctor, as they will advise you on how to make sure your baby can quickly get the fluids they need.

Baby Fever Danger Signs to Watch Out For

More serious signs of baby fever12 include weak and continuous crying, blue lips, tongue or nails, sluggishness or difficulty waking up, being unresponsive, and, rarely, fits and seizures. If your baby shows any of these signs, seek emergency care immediately.

Should You Take Your Baby to the Doctor at the First Sign of Sickness?

As the weeks and months go by, you’ll get to know your baby better, and you’ll get to understand what’s “normal” for them. There will be times, however, when it’s not always easy to spot if they’re sick, and whether you should make a call to the doctor.

Look out for any change in your baby’s behaviour, as this is often a sign they might be ill. The most obvious sign, of course, is a baby fever, which is usually a clear indication that your baby’s body is fighting an infection13. A raised temperature can be accompanied by flushed cheeks and more glassy-looking eyes, but it’s important to remember that fevers affect babies in different ways.

If in doubt, always contact your doctor. It may be that a quick telephone consultation is all that’s needed to get the right advice. Don’t ever feel that any question you have about your baby’s well-being is too ridiculous! Remember, all babies are different, and the ways that illnesses present themselves in your child will vary, too.

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1. Kelly, Mary Ann, "Common Childhood Illnesses: Improving Parent/Guardian Education" (2019). Family Medicine Clerkship Student Projects. 530.
3. Ibid
6. Tham EK, Schneider N, Broekman BF. Infant sleep and its relation with cognition and growth: a narrative review. Nat Sci Sleep. 2017;9:135-149. Published 2017 May 15. doi:10.2147/NSS.S125992
8. Ibid
11. Kelly, Mary Ann, "Common Childhood Illnesses: Improving Parent/Guardian Education" (2019). Family Medicine Clerkship Student Projects. 530.