It's 2 AM. Your kid is warm. You grab the thermometer. It reads 101.8. Now what?
I'm not a doctor, and this isn't medical advice. But I've sat in that dark room too, trying to decide whether to call the nurse line, wait until morning, or drive to the ER. The research helped me. Maybe it'll help you.
The one rule you need to memorize
Under 3 months old: any rectal temperature of 100.4°F or higher is a medical emergency. Call your pediatrician or go to the ER immediately. Don't give medicine first. Don't wait.
Babies this young have immature immune systems. Serious infections progress fast. Fever might be the only sign something's wrong, even if the baby looks fine. The AAP published specific clinical guidelines for this in 2021. This one isn't a judgment call.
After 3 months, it gets less scary
Here's how pediatricians think about it by age:
3 to 6 months
Call the pediatrician for any fever at or above 100.4°F, especially if the baby seems sick. Over 102°F, call that day.
6 months to 2 years
Call if the fever tops 102°F or lasts more than 24 hours. Watch closely and call sooner if symptoms get worse.
Over 2 years
Stop watching the thermometer. Watch your kid. Call if the fever lasts more than three days, hits 104°F, or comes with the warning signs below.
Any age
104°F or higher, a seizure, or any of the emergency signs listed below means go now.
The number matters less than how they look
This is the part most parents get wrong, and it's not their fault. Researchers have been studying "fever phobia" since 1980, when Dr. Barton Schmitt surveyed 81 parents and found that more than half believed a temperature under 104°F could cause brain damage. It can't.
Twenty years later, a follow-up study found the fear hadn't changed. Parents still panicked at low-grade fevers and reached for medicine too soon.
The truth: your child's brain regulates their temperature. Fevers from common infections rarely top 103-104°F and essentially never reach levels that cause harm. Fever is the immune system doing its job. What matters isn't the number -- it's how the child acts, whether they're drinking fluids, and whether anything else is going on.
Warning signs that change everything
Forget the thermometer for a second. These symptoms mean call the doctor now or go to the ER, regardless of what the temperature says:
- Trouble breathing or fast breathing
- A stiff neck
- A rash that doesn't fade when you press on it, or looks like bruises
- A seizure
- Hard to wake up, unusually sleepy, or "not themselves"
- Blue lips or fingernails
- Bulging soft spot (infants)
- Inconsolable crying
- Repeated vomiting or diarrhea
- Signs of dehydration: dry lips, no tears, very few wet diapers
- Won't drink or eat (especially infants)
The overriding rule from every pediatrician I've read: trust your gut. If your child looks very sick, get help regardless of the number.
The Tylenol and Motrin question
Start with one medicine, not both. Acetaminophen (Tylenol) works from about 2 months. Ibuprofen (Motrin) only from 6 months.
Alternating them does bring the fever down slightly more than using one alone. A 2024 review of 31 studies confirmed this. But the AAP cautions against it because parents mix up doses, double up accidentally, and chase a number instead of treating discomfort.
The goal of medication is comfort, not a normal temperature reading. If your kid is miserable, give medicine. If they have a 101°F fever but they're running around the living room, they might not need anything.
Always dose by weight, not age. Use the measuring tool that comes with the medicine. And never give aspirin to a child -- it's linked to a rare but serious condition called Reye's syndrome.
The seizure that looks terrifying but isn't
Febrile seizures happen to 2-5% of kids between 6 months and 5 years. They're the most common seizure disorder in childhood. They look awful. Shaking, stiffness, eyes rolling back.
But the AAP says febrile seizures do not cause brain damage, do not lower intelligence, and do not cause learning disabilities. About a third of kids who have one will have another. The AAP recommends against preventive medication because the medicine carries more risk than the seizures do.
If it happens: put your child on the floor or bed, away from anything sharp. Turn them on their side. Don't put anything in their mouth. Don't hold them down. Time the seizure. If it lasts more than 5 minutes, call 911.
After any first seizure, call your pediatrician. But know that the seizure itself, as terrifying as it looks, is almost certainly harmless.
The 2 AM decision tree
Here's what I keep on my phone for the middle of the night:
Go to the ER now if: baby under 3 months with any fever; seizure lasting more than 5 minutes; trouble breathing; won't wake up; blue lips.
Call the doctor now if: fever above 104°F at any age; fever with rash, stiff neck, or repeated vomiting; signs of dehydration; the child looks very sick to you.
Call in the morning if: fever between 102-104°F lasting more than a day (under 2 years) or more than three days (over 2 years); fever comes back after seeming to break; child has a chronic condition.
Watch at home if: child is over 6 months, fever is under 102°F, they're drinking fluids, and they're acting like themselves between fever spikes.
When in doubt, call. Every pediatrician's office has a nurse line. That's what it's for.
One more thought
You're reading this because you just Googled your kid's fever. Google now stores that search in your profile. If your account is older than 2020, Google stores it forever by default.
Ask Safely is an AI you can ask any health question -- fevers, symptoms, medication dosing, whether to call the doctor -- and the conversation disappears in 8 hours. No ads from children's hospitals following you around the internet afterward.