Fever 101: When to Worry and When to Let It Run Its Course

When your kid’s temperature spikes, the situation can go from zero to panic in about 3.5 seconds. One minute they’re dozing off after that dose of Tylenol, the next they’re radiating enough heat to power a small city, and you’re frantically Googling, “How high is too high?”

This is exactly when you need a trusted source of information by your side. Our Fever 101 cuts through the noise with straight answers to the questions keeping you up at night: “When does this become an ER situation?” and “What red flags should actually worry me?”

What Is a Fever? Understanding the Basics

Fever is a symptom and an immune response, not an illness itself. The body releases chemical signals telling the brain to raise the temperature to fight an infection. In addition to feeling hot, your child might display other symptoms like:

• Chills
• Headache
• Aches and pains
• Fatigue

Why Fevers Happen: The Body’s Natural Defense Mechanism

When a fever turns your child into an inferno, it feels like your worst enemy. But a fever can be a good thing—it’s a sign that your kid’s immune system is doing its job to fend off the infection that triggered it.

What Temperature Counts as a Fever? 

The AAP (American Academy of Pediatrics) defines fever as 100.4°F (38°C) or higher in both infants and older children. What to do when a fever is present depends on a number of factors, including the age of the child, the accompanying symptoms, and how long the symptoms have been present. So, pay attention to how your child is acting and other signs. 

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Here are the symptoms that can accompany a fever that may warrant a trip to the doctor:

Concerning Symptoms with Fever

• Behavior changes
• Child is less verbal than usual or not responding normally
• Child cannot be consoled with normal comforting measures
• Difficulty waking or not interacting at baseline
• Child remains miserable even after fever-reducing medication

Dehydration Signs

• Refusing fluids
• Not making wet diapers/not urinating
• Chapped lips
• Sunken eyes

Breathing Difficulties

• Nostrils flaring in and out
• Spaces between the ribs flaring (retractions)
• Rapid breathing

Common Causes of Fever in Children

There are many reasons why your little one may get a fever, including:

• Infections
• Viral infections (most common cause)
• Common cold
• Teething
• Reaction to a vaccination
• Allergies
• Inflammatory diseases—for example, juvenile rheumatoid arthritis

When to Let a Fever Run Its Course

Should I let my child's fever run its course? will be one of your key questions when your little one breaks out in a sweat. Here’s what you need to know.

The Benefits of Fever: How It Helps Fight Infections

While a fever can be concerning, remember,  it can actually help your little one get better.

The heat that fever produces makes immune cells work better and targets infected body cells. The impact? The immune system kicks into action to fend off invading bacteria or viruses and speed up your little one’s recovery. If it’s not making your child uncomfortable, it’s okay to let it run its course and not medicate. 

Safe Home Remedies for Managing Fever

You’ll be relieved to know that there are some simple steps you can take at home to manage your kid’s fever:

• Keep them hydrated. This is essential, as fever can increase the risk of dehydration in children.
• Let them rest. Get your child comfy in a quiet, cool room.
• Give them a lukewarm bath. Let your child relax in a tepid bath to soothe and relax them.
• Dress them in light clothing. Choose loose clothes in natural fabrics like cotton.

Myths vs. Facts About Fevers (Why You Don’t Always Need to Lower a Fever Immediately)

Fevers can feel scary. But it’s important to be able to distinguish between fever myths and facts. Here’s what every parent needs to know about fevers:

Myth: You Should Treat Every Symptom of Illness with Medication

Symptoms like chills, headaches, aches and pains, and fatigue that often accompany fevers can be treated with natural remedies like the ones we’ve listed above.

Myth: A Fever Is Always a Bad Thing

A fever indicates that your child’s immune system is doing its job—so that’s good news! So when is a fever potentially bad? When it is present in very young infants or it comes with more serious symptoms, inconsolability, breathing difficulties, seizures or dehydration. Again, what to do in each case depends on a number of factors, including the age of the child, the accompanying symptoms, and how long the symptoms have been present. If you are ever unsure, contact your provider.

Myth: My Kid Will Get a Seizure from a Fever

In rare cases, a child may experience a seizure as the result of a fever. But don’t panic just yet—this only happens in 2% to 4% of children up to the age of five.

When to Worry: Signs a Fever Needs Medical Attention

While in many cases a fever can be managed at home, you should know the signs that your child needs medical attention.

Be aware of these high-risk temperature levels, which vary by age: 

Child's age High-risk temperature level

Newborn to 3 months: 100.4°F (38°C) or above

3 months and over: 100.4.°F (39°C) or above with the following symptoms: dehydration, difficulty breathing, inconsolability, or signs mentioned in section above

For older kids, their behavior will tell you more than a number—some kids just run hot! Look out for the concerning fever symptoms that we've listed above, rather than focusing solely on their temperature.

When to Seek Medical Attention for a Fever: Doctor vs. ER

Unsure about what can be managed at home versus what needs a doctor? We got you. The below guide can help you determine when to call your pediatrician and when to seek emergency care:

Age-Based Guidelines

Under 1 Month with ANY Fever (100.4°F/38°C+)

Fever is a medical emergency, and you should go to the hospital immediately.

1-2 Months with Fever

Emergency evaluation is often needed (the doctor may direct you to the ER anyway).

2-3 Months with Fever

Call your doctor first—they'll determine if immediate evaluation is needed.

3+ Months with Fever

Doctor visit recommended if:

• Fever persists over 5 days, and there are signs of a virus 
• Fever persists over 5 days, and there are no other signs causing the fever (runny nose, vomiting)
• Child's first-ever fever (in this situation, it's reasonable to get checked)
• Child seems unusually uncomfortable

Concerning Symptoms (Call the Doctor)

• Child not acting like themselves but still drinking/urinating
• Mild to moderate discomfort that partially responds to fever reducers
• Specific pain (ear pain, sore throat, etc.) with fever
• Fever comes and goes but child is generally improving
• Fever with typical cold symptoms (cough, congestion) in a child who is otherwise acting relatively normal

When to Go Directly to the ER

In these situations, bypass the doctor and go straight to ER:

Fever with breathing difficulties:

• Rapid breathing
• Flaring nostrils
• Pulling in of the ribs (retractions)
• Grunting sounds

Fever with severe dehydration:

• Not keeping any liquids down
• No urination
• Sunken eyes
• Chapped lips

Fever with extreme behavioral changes:

• Difficulty waking
• Extreme lethargy
• Inconsolable crying
• Child "went from zero to hero or zero to zero" (sudden dramatic change)

Poppins expert Dr. Mona says, "When you're deciding between taking your child to the doctor or ER, ask yourself, 'Do they need an intervention?' Meaning, 'Does my child maybe need blood work, IV fluids, or imaging?' If the answer is yes, or if your gut tells you something is seriously wrong, go to the ER."

How to Safely Treat a Fever

Are you wondering, How to break a fever in a child? Here’s what to do to get your child’s temperature down.

You may want to give medication to treat a fever above 102°F (38.9°C). If so, we recommend reviewing this dosing chart for acetaminophen (for babies over three months) and ibuprofen (for babies over six months). Remember, before giving medication to your child: 

• You should avoid giving ibuprofen if your child is dehydrated or vomiting and consider acetaminophen instead. Don’t give your child aspirin—it may cause a rare disease called Reye’s syndrome, which damages the liver and brain. As mentioned above, there are also home remedies you can try that don’t require any medication. Try keeping your kid cool with these simple tricks:
• Dressing them in light clothing
• Using a fan or air conditioning in their room
• Bathing them in lukewarm water
• Using a cool compress

Once your child has turned a corner (thank goodness!), this is what you can do to keep them comfy while they recover:

• Get hydration levels up with plenty of fluids, popsicles, soup, or jello.
• Encourage them to eat regular, nutritious meals.
• Ensure they have a cozy space where they can relax and recover.
• At night, dress them in light layers so they don’t get overheated.

Fever Prevention and Immune Support

Fevers are definitely something you want to avoid. To prevent conditions that might lead to fever:

• Keep your child's vaccinations up-to-date—vaccines like the pneumococcal vaccine have reduced ear infections, which can cause fevers.
• Strengthen your kid’s immune system through balanced nutrition and sleep.
• Encourage frequent handwashing.

If your child keeps getting fevers or gets fevers without other symptoms, they may have “periodic fever syndrome.”

This term covers a range of conditions where kids get fevers without infections or other known causes. If you notice this pattern, get your child checked out by the pediatrician.

Final Thoughts: Trust Your Parental Instincts

Fevers aren’t fun, but by understanding how to treat them and when to get help, you should feel better equipped to deal with them.

Above all, trust your parental instincts. Dr. Mona says, "I've never had a situation where a parent comes to the office, and they didn't know they needed to bring their kid in. It's one of those gut things."

So, if your child’s temperature spikes and you need medical care, get them seen by a medical professional or connect with one of Poppins’ 24/7 on-demand pediatric providers —when it comes to little ones, it’s always better to be safe than sorry.