Fever in Babies: What You Need to Know

Fever in babies is something every parent worries about, and that’s totally normal. When your little one feels warm or uncomfortable, it can be scary not knowing what’s happening or what to do next. 

The good news is that most fevers in babies are just the body’s way of fighting off infections, like a cold or flu. But how high is too high? When should you worry, and when can you just stay calm and watch?

Keep reading, and we’ll walk you through everything step-by-step so you feel confident caring for your baby.

What is a Fever?

When we say a baby has a fever, it means their body temperature is higher than what’s normal for them. So, you might be wondering, “What is infant fever temperature exactly?” Well, a fever happens when your baby’s body temperature goes above the usual level.

If you take your baby’s temperature by gently checking their bottom, that’s called taking it rectally, and the number is 100.4 degrees Fahrenheit or higher (which is about 38 degrees Celsius), that means your baby has a fever.

If you check the temperature under your baby’s armpit instead, the number for a fever is a bit lower — about 99 degrees Fahrenheit or higher (around 37.2 degrees Celsius).

So, depending on where you check, the number that shows a fever can be a little different, but both tell you if your baby’s temperature is higher than normal.

Doctors say that having a fever usually means your baby’s body is fighting something, like a cold or the flu. It’s their body’s natural way of trying to get better.

How to Take Your Baby’s Temperature Correctly

The best way to get the most accurate reading of your infant's temperature is to take it rectally. This means gently inserting a digital thermometer about half an inch inside their anus. 

This might sound scary, but it’s the safest and most precise way. Here’s how you can take your baby’s temperature rectally:

1. Wash the thermometer with soap and water.

2. Put a little petroleum jelly on the tip.

3. Lay your baby on their stomach or hold their legs gently.

4. Slowly insert thermometer about ½ inch into the anus.

5. Hold it steady until it beeps.

6. Remove and check the reading.

Note: Avoid using forehead strips or ear thermometers for babies younger than 6 months, as they can be less accurate.

Causes of Fever in Babies

Most fevers in babies happen because of infections. The most common are viral infections like colds and the flu, which cause most fevers. Sometimes bacteria cause fever too, like in urinary tract infections or strep throat. 

Babies can also get a fever after vaccines, but this is normal and usually goes away quickly. Another cause is overheating, which can happen if a baby wears too many clothes or is in hot weather. This usually causes a low fever.

But if your baby is under 3 months old, a fever could be a sign of a serious infection like sepsis or meningitis, and they need urgent medical care right away.

Will Teething Cause a Fever?

You might wonder, will teething cause a fever? Research shows that teething does not cause a fever. If your baby has a fever during teething, it’s probably because of something else going on.

Signs Your Baby Has a Fever

Besides the thermometer reading, you may notice:

1. Baby feels warm or hot to the touch

2. Flushed or red skin

3. More crying or fussiness than usual

4. Poor sleeping or eating

5. Less interest in playing or moving

6. Sometimes shivering or sweating

If your baby is acting very differently, especially if they are very sleepy, not eating, or difficult to wake up, you should take it seriously.

How High is Too High? Baby Fever Chart and Temperature Guide

To help you understand fever levels, here’s a simple baby fever chart and temperature guide:

Fever in Babies: When to Worry

So, let’s talk about fever in babies and when you should start to worry. If your baby is under 3 months old and the body temperature goes over 100.4 degrees Fahrenheit, that’s something you shouldn’t wait on. Get medical help right away. 

Now, if your baby is a bit older, like around 4 months, and they have a high fever, or the fever sticks around for more than 3 days, it’s best to call the doctor. Sometimes there’s a fever in babies with no other symptoms, and if your baby is still eating, playing, and acting mostly normal, you usually don’t need to panic. 

But if your baby has trouble breathing, seems very sleepy or hard to wake, cries non-stop, or has a seizure, don’t wait. See a doctor right away. And if you notice that your toddler has a fever for 4 days with no other symptoms, it’s a good idea to have them checked too, just to make sure everything’s okay.

Also, not all cries mean hunger. Sometimes, fever is the reason. Learn how to tell why babies cry.

How to Treat Fever in Babies at Home

If your baby has a fever but seems mostly okay, there are a few simple things you can do at home to help them feel better and bring the fever down gently.

• Keep your baby hydrated: Offer extra fluids like breast milk or formula for babies under 6 months, and water for older babies. Staying hydrated helps the body cool down.

• Dress your baby lightly: Use one layer of light clothing. Don’t bundle your baby up; overheating can make fever worse.

• Use fever medicine if needed: For babies older than 3 months, you can give acetaminophen (Tylenol) or ibuprofen (Advil) (ibuprofen only after 6 months).

• Do not give aspirin. It can cause serious illness (Reye syndrome). Don’t give fever medicines to babies under 3 months without talking to a doctor first.

• Lukewarm baths: A lukewarm bath can help cool your baby down. Make sure the water is not cold or hot.

When to Call the Doctor or Get Emergency Help

Sometimes, a fever in babies can be a sign of something more serious. So here’s exactly when you should call the doctor or head to the emergency room without waiting.

Call Emergency (911 or Go to ER Immediately) If Your Baby:

1. Is not moving or cannot be woken up

2. Has severe trouble breathing or can barely cry or speak

3. Has purple or blood-colored spots on their skin

4. Has a seizure with the fever

5. Has a very stiff neck or a swollen soft spot on the head.

Call the Doctor Right Away If Your Baby:

• Is under 12 weeks old with any fever of 100.4°F or higher

• Has a fever over 104°F (40°C)

• Has trouble breathing, but not severe

• Has shaking chills for over 30 minutes

• Won’t stop crying or crying when touched or moved

• Won’t move an arm or leg normally.

• Shows signs of dehydration like no pee for 8 hours, dry mouth, no tears when crying

Call the Doctor within 24 Hours If Your Baby:

• Is 3 to 6 months old with a fever (infant fever 4 months old fits here)

• Has fever over 24 hours without other symptoms (in babies 6-12 months)

• Fever lasts more than 3 days

• Fever returns after going away for more than a day.

Why Having a Good Diaper Bag Matters When Your Baby Has a Fever

When your baby has a fever, you might need to head out quickly, maybe to the doctor, or just to soothe them with a change of clothes, a clean diaper, or their favorite toy. And let’s be honest, the last thing you want to do when your baby’s not feeling well is dig through a messy bag. That’s why a smart, organized bag like the Swaddle Tote diaper bag makes such a big difference.

It has space for everything, like diapers, wipes, a thermometer, baby medicine, bottles, extra clothes, even your own phone and wallet. The Parent Bag holds all the big things, and the smaller Sidekick Bag is perfect for quick trips when you don’t want to carry too much. 

It even has a built-in changing pad, so if your baby needs a quick diaper change while you’re out, you’re ready. And because it looks stylish and doesn’t scream “baby bag,” you’ll feel good carrying it anywhere.

Trust us, when your baby’s feeling unwell, being prepared with the right bag makes things less stressful for both of you.

When your baby has a fever, packing smart really helps. See what essentials to carry in your diaper bag here.

Wrapping Up

So, to sum it all up, a fever is usually just your baby’s way of fighting off an infection, most often a virus. But if your baby is under 3 months old and has a fever, they need urgent medical care right away. For older babies, most fevers between 100 and 104 degrees Fahrenheit are not dangerous, but it’s always important to watch how your baby is acting. 

If they seem very sleepy, look sick, or show signs of dehydration like no wet diapers or a dry mouth, don’t wait, get help instantly. Also, always use the right way to check temperature, and rectal thermometers are the most accurate for babies. Keep your baby lightly dressed, make sure they get enough fluids, and only use fever medicine if your baby seems uncomfortable. 

And most importantly, never hesitate to call your doctor or emergency services if something doesn’t feel right.