When to Call Your Pediatrician for a Fever: A Parent’s Guide by Age

Medically reviewed by the pediatric team at Desert Valley Pediatrics

Few things worry a parent more than a child with a fever. Your little one feels warm, they’re fussy, and your first instinct is to call the doctor or rush to the emergency room. But here’s the reassuring truth: most fevers are a normal sign that your child’s immune system is doing its job.

That said, there are times when a fever does need medical attention, and when it does, knowing the right steps can make all the difference. This guide will help you understand what a fever really means, when to call your pediatrician, and when to head in for a visit at one of our Las Vegas offices.

 

What Actually Counts as a Fever?

The American Academy of Pediatrics (AAP) defines a fever as a rectal temperature of 100.4°F (38°C) or higher. That number applies to children of all ages.

Here are a few important things to keep in mind about taking your child’s temperature:

• For babies under 3 months, a rectal thermometer is the most accurate method.
• Forehead (temporal artery) thermometers are convenient for toddlers and older children, but may read slightly lower.
• Ear thermometers can be unreliable in infants under 6 months.
• A child who “feels warm” to the touch may not actually have a fever; always confirm with a thermometer.

Tip: If you’re unsure how to take your child’s temperature correctly, our team is happy to walk you through it at your next visit.

 

Fever Guidelines by Age: When to Call

Not all fevers are created equal. Your child’s age is one of the most important factors in deciding how to respond. Here’s a breakdown:

Newborns (0–3 Months)

⚠️ Call your pediatrician immediately Any rectal temperature of 100.4°F (38°C) or higher in a baby under 3 months requires a prompt call to your pediatrician — even if your baby seems otherwise fine.

Young infants have immature immune systems, which means even a low-grade fever can indicate a serious infection. Don’t wait to see if the fever resolves on its own. Contact our team right away, day or night.

Infants (3–6 Months)

Call your pediatrician if your baby’s temperature reaches 101°F (38.3°C) or higher, or if a lower fever is accompanied by unusual fussiness, poor feeding, or lethargy.

At this age, many fevers are related to common viruses, but your pediatrician will want to evaluate your baby to rule out anything more concerning.

Babies and Toddlers (6–24 Months)

For children in this age range, a fever on its own isn’t usually an emergency. Call your pediatrician if:

• The fever is 102°F (38.9°C) or higher and lasts more than one day.
• Your child has a fever with a rash, persistent vomiting, or diarrhea.
• Your child seems unusually irritable, lethargic, or difficult to console.
• The fever returns after being gone for more than 24 hours.

Children (2 Years and Older)

Older children can generally tolerate fevers better, and low-grade fevers don’t always require a call. Reach out to your pediatrician if:

• The fever is 104°F (40°C) or higher.
• The fever lasts more than three days, even if it’s low-grade.
• Your child complains of a stiff neck, severe headache, or persistent sore throat.
• Your child is not drinking enough fluids or has decreased urination.
• You notice any of the warning signs listed below.

Have questions about your child’s symptoms? Call our Las Vegas offices or message us through the Patient Portal.

 

Warning Signs: When to Seek Immediate Care

Regardless of your child’s age, certain symptoms alongside a fever warrant an urgent call to your pediatrician or a trip to the nearest emergency room:

Seek immediate care if your child has a fever and: Difficulty breathing or rapid, labored breathing A rash that looks like small purple or red dots that don’t fade when you press on them Extreme lethargy or unresponsiveness, much more than normal sleepiness A stiff neck combined with sensitivity to light Signs of dehydration: no wet diapers for 8+ hours, no tears when crying, sunken soft spot in infants A seizure (febrile seizures can happen in young children and are frightening but usually not dangerous; still, call immediately) A fever in a child with a weakened immune system or a chronic medical condition

 

Managing a Fever at Home

If your child has a mild fever and is otherwise acting fairly normal, still playing, drinking fluids, and making eye contact, you can often manage things at home while keeping an eye on their symptoms.

• Keep your child comfortable and lightly dressed. Bundling can trap heat.
• Offer plenty of fluids, such as water, breast milk, formula, or an electrolyte solution like Pedialyte.
• Use age-appropriate fever reducers (acetaminophen for babies 2 months and older; ibuprofen for children 6 months and older). Always follow the dosage on the label or ask your pediatrician for guidance.
• Let your child rest. A fever is the body’s way of fighting infection, and rest supports that process.
• Avoid cold baths or rubbing alcohol; these old remedies can actually make things worse.

Important: Never give aspirin to a child or teenager. Aspirin has been linked to Reye’s syndrome, a rare but serious condition.

 

How to Reach Desert Valley Pediatrics

If you’re concerned about your child’s fever, we want to hear from you. Here’s how to get in touch:

• During office hours: Call any of our Las Vegas-area locations, including our Summerlin and Centennial Hills offices, and our front desk team will help you determine if your child needs a same-day appointment.
• After hours: Use our Patient Portal to send a message to your child’s care team. For urgent concerns after hours, our answering service can connect you with a provider.
• ¿Habla español? Our team includes Spanish-speaking staff members who are available to help you in the language you’re most comfortable with.

Ready to schedule an appointment? Call us today or visit desertvalleypediatricslv.com to book online. We’re here for your family — whether it’s a fever at midnight or a well-child check on a Tuesday.

 

When in Doubt, Call

As pediatricians, we’d always rather hear from a worried parent than have a child’s symptoms go unchecked. There’s no such thing as calling too early, and a quick conversation with our team can save you a stressful trip to the ER. Trust your instincts. You know your child better than anyone. If something doesn’t feel right, reach out. That’s exactly what our pediatricians are here for.

 

Frequently Asked Questions

Is 99°F considered a fever in a child?

Not technically. The AAP defines a true fever as a rectal temperature of 100.4°F (38°C) or higher. A reading of 99°F may be slightly elevated, sometimes called a “low-grade fever,” but it can also reflect normal body temperature fluctuations, especially later in the day or after physical activity.

Should I let my child’s fever run its course or give medicine right away?

A fever itself isn’t harmful; it’s the body’s natural defense against infection. You don’t always need to treat a low-grade fever with medication, especially if your child is comfortable, drinking fluids, and acting relatively normal. Fever reducers like acetaminophen or ibuprofen are most helpful when your child is uncomfortable, having trouble sleeping, or not drinking well. When in doubt, call our office for guidance on the right approach for your child.

Can teething cause a fever?

Teething may cause a slight rise in body temperature, but research shows it doesn’t cause a true fever of 100.4°F or higher. If your teething baby has a fever at or above that threshold, something else like a viral infection is likely the cause, and it’s worth contacting your pediatrician.

What is a febrile seizure, and should I be worried about one?

A febrile seizure is a convulsion triggered by a rapid rise in body temperature. They’re most common in children between 6 months and 5 years old and typically last less than a few minutes. While terrifying to witness, most febrile seizures are not dangerous and don’t cause lasting harm. If your child has a seizure, lie them on their side, don’t put anything in their mouth, and call your pediatrician or 911 right away.

How long is too long for a child’s fever to last?

For most children over 2 years old, a fever lasting more than three days deserves a call to the pediatrician, even if it’s low-grade. For younger infants, the timeline is shorter: call immediately for any fever in babies under 3 months, and within 24 hours for babies 3 to 6 months. A fever that goes away and then returns after a day or more can also signal a secondary infection and should be reported.

Can I alternate acetaminophen and ibuprofen for my child’s fever?

Some pediatricians do recommend alternating these medications for persistent or high fevers, but it’s important to get specific dosing guidance from your child’s doctor first. Alternating without clear instructions can lead to accidental overdosing. Call Desert Valley Pediatrics, and we can walk you through a safe schedule based on your child’s age and weight.

My child has a fever, but is acting normal. Should I still worry?

A child who has a low-grade fever but is still playing, eating, and drinking is generally not in immediate danger. It’s okay to monitor at home and keep them comfortable. That said, keep a close eye on how the fever progresses over the next 24–48 hours, and don’t hesitate to call your pediatrician if anything changes or for peace of mind. Reach out through our Patient Portal anytime.

Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. The guidance provided aligns with general recommendations from the American Academy of Pediatrics (AAP). Always consult your child’s pediatrician with any questions about a medical condition.