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

Medically reviewed by the pediatric team at Desert Valley Pediatrics

Key takeaways

• Call right away for any temperature of 100.4°F (38°C) or higher in a baby under 3 months old.
  
• At any age, call if the fever repeatedly reaches 104°F (40°C) or higher, or if your child looks very sick, acts very drowsy, or can’t be consoled.
  
• Call if a fever lasts more than 24 hours in a child under 2, or more than 3 days in a child 2 or older.
  
• Get help right away if a fever comes with trouble breathing, a stiff neck, purple spots, a seizure, or signs of dehydration.

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. The good news: most fevers are a normal sign that your child’s immune system is doing its job.

This guide tells you when to call, when to come in, and when to head to the ER.

When to Call the Pediatrician Right Away (Any Age)

Call us right away if your child has a fever and:

• A temperature that repeatedly reaches 104°F (40°C) or higher
• Extreme lethargy or unresponsiveness, much more than normal sleepiness
• Extreme fussiness that nothing soothes
• 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
• A stiff neck combined with sensitivity to light
• A seizure
• Signs of dehydration: no wet diapers for 8+ hours, no tears when crying, sunken soft spot in infants
• A weakened immune system, a heart problem, or a chronic medical condition
• Recent time in extreme heat, such as an overheated car. Heat illness can look like a fever and needs care right away. Move your child to a cool place and call us.

Need to be seen today? Ask about same-day sick appointments.

Fever Guidelines by Age and Duration

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

Newborns and Infants Under 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. If you can’t reach us, go to the nearest emergency room.

Babies and Toddlers (3 Months to 2 Years)

A fever on its own isn’t usually an emergency at this age. Call your pediatrician if:

• The fever lasts more than 24 hours without improving.
• The fever returns after being gone for more than 24 hours.
• Your child has a fever with a rash, persistent vomiting, or diarrhea.
• Your child seems unusually irritable, lethargic, or difficult to console.

Children 2 Years and Older

Older children 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 isn’t drinking enough fluids or has decreased urination.
• You notice any of the warning signs listed above.

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

Call, Come In, or Go to the ER?

• Call us or come in: Your child meets the criteria above and stays alert, drinking, and responsive.
  
• Go to the ER or call 911: Your child has trouble breathing, extreme lethargy or unresponsiveness, or a seizure. Go to the ER for a fever in a baby under 3 months if you can’t reach us.
  
• If your child has a seizure: Febrile seizures can happen in young children and are frightening but usually not dangerous. Lay your child on their side, don’t put anything in their mouth, and call your pediatrician or 911 right away.
  
• 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. You can also ask whether a telehealth visit fits your child’s symptoms.

What Counts as a Fever, and How to Take a Temperature

The American Academy of Pediatrics (AAP) defines a fever as a rectal temperature of 100.4°F (38°C) or higher. A reading of 99°F is usually normal variation, especially later in the day or after physical activity.

Keep these tips in mind:

• 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 have a fever at all. 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. You can also review the AAP’s guide to taking a child’s temperature.

How to Care for a Fever at Home: Treat the Child, Not the Number

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. Focus on how your child acts, not the number on the thermometer. You don’t need to bring the temperature back to normal.

• Dress lightly. Keep your child comfortable. 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). Follow the dosage on the label, track each dose, and ask us for guidance before you combine or alternate medicines.
  
• Let your child rest. A fever is the body’s way of fighting infection, and rest supports that process.
  
• Skip cold baths and rubbing alcohol. These old remedies can make things worse.
  
• Call us if your child still seems sick after the fever comes down, or if they get worse.

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

Fever FAQs

How long should a child’s fever last?

Viral fevers often come and go over a few days. Whatever the cause, call if a fever lasts more than 24 hours in a child under 2, or more than 3 days in a child 2 or older. Call us too if a fever goes away and then returns after a day or more, which can signal a secondary infection.

When can my child go back to school or daycare after a fever?

Most schools and daycares ask that your child stay home until they’ve been fever-free for 24 hours without fever-reducing medicine. Check your school’s policy, and call us if you have questions.

Is a fever from a virus or bacteria?

A fever alone doesn’t tell you. Viruses cause most childhood fevers, but bacteria cause some, and the two can look alike at home. Your pediatrician looks at your child’s age, symptoms, and exam to decide whether testing or treatment is needed. Antibiotics don’t treat viruses.

Can vaccines cause a fever?

Yes. A low-grade fever for a day or two is a common side effect. If your child is otherwise comfortable, you can usually monitor at home. Any fever of 100.4°F or higher in a baby under 3 months still needs a call to us.

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, so contact your pediatrician.

My child has a fever but is acting normal. Should I 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. Keep a close eye on how the fever progresses over the next 24 to 48 hours, and call if anything changes or for peace of mind. Reach out through our Patient Portal anytime.

We’re Here When Your Child Has a Fever

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. Trust your instincts. You know your child better than anyone. If something doesn’t feel right, reach out.

• During office hours: Call any of our Las Vegas-area offices in Summerlin, Centennial Hills, or Southern Hills. Our front desk team will help you decide whether your child needs a same-day appointment.
  
• After hours: Use the Patient Portal or our answering service, as described above.
  
• ¿Habla español? Nuestro equipo incluye personal que habla español y están disponibles para ayudarle en la idioma con el que se sienta mas cómodo.

Ready to schedule an appointment?

We’re here for your family, whether it’s a fever at midnight or a well-child check on a Tuesday. Book an Appointment Online or  Call (702) 260-4525

New to DVP? See our new patient page.

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.