Yes, 38°C (100.4°F) is the standard threshold for a fever in children. If your child’s temperature reaches 38°C or higher when measured rectally, orally, or with an ear or forehead thermometer, that reading counts as a fever. This is the cutoff used by the American Academy of Pediatrics and most pediatric guidelines worldwide.
That said, a temperature of exactly 38°C is at the very bottom of the fever range. What matters most isn’t the number itself but your child’s age, how they’re acting, and whether other symptoms are present.
How the Thermometer Method Changes the Number
The 38°C threshold applies when you’re using a rectal, ear, or temporal artery (forehead) thermometer. If you’re taking your child’s temperature under the arm (axillary), the fever cutoff is lower: 37.2°C (99°F) or higher. That’s because armpit readings run cooler than core body temperature. If an armpit reading seems borderline or doesn’t match how your child looks and feels, it’s worth rechecking with a different method.
For babies under three months, rectal thermometers give the most reliable reading. For older toddlers and children, ear and forehead thermometers are practical and reasonably accurate. Oral thermometers work well once a child is old enough to hold one under their tongue with their mouth closed, usually around age four or five.
Age Makes a Big Difference
A reading of 38°C means very different things depending on whether your child is eight weeks old or eight years old.
For any baby younger than three months, a temperature of 38°C or above warrants an immediate call to your pediatrician, even if the baby seems fine otherwise. Young infants have immature immune systems, and fever at this age can signal a serious infection that isn’t obvious from the outside. The American Academy of Pediatrics specifically addresses the evaluation of otherwise well-appearing infants between 8 and 60 days old who develop a fever at or above 38°C, treating it as a situation that needs prompt medical assessment.
For children older than three months, a fever of 38°C on its own is usually not an emergency. Fever is the body’s normal response to fighting off an infection. Most fevers in this age group are caused by common viral illnesses and resolve within a few days without any specific treatment beyond comfort care.
Warning Signs That Need Attention
Rather than fixating on the exact number, pay close attention to how your child is behaving. A child with a 38.5°C fever who is still playing and drinking fluids is generally in better shape than a child with the same temperature who can’t be consoled. Specific red flags to watch for include:
- Extreme sleepiness or unresponsiveness. If your child is unusually difficult to wake up or doesn’t respond to your voice or touch, that’s a serious concern.
- Signs of dehydration. Dry mouth, cracked lips, no tears when crying, fewer than six wet diapers in 24 hours, or a sunken soft spot on a baby’s head all point to dehydration that needs medical attention.
- Persistent, unusual crying. A high-pitched cry that can’t be soothed, especially in an infant, may signal pain or distress beyond what a typical fever causes.
- Repeated vomiting. If your child can’t keep fluids down, dehydration can develop quickly.
Febrile Seizures
Some parents worry about fever-related seizures, called febrile seizures. These occur most often in children between 6 months and 5 years old, with peak risk between 12 and 18 months. They can be frightening to witness, but the important thing to know is that they’re typically triggered by how rapidly the temperature rises, not by how high it gets. Most febrile seizures happen in the first few hours of a fever, during the initial spike. Even a low-grade fever can trigger one in a susceptible child. Giving fever-reducing medication doesn’t reliably prevent them.
Managing a Fever at Home
For children over three months with a low fever like 38°C, the goal of treatment is comfort, not eliminating the fever entirely. If your child seems uncomfortable, acetaminophen or ibuprofen can help bring the temperature down and ease achiness. Acetaminophen can be given every four to six hours (no more than five times in 24 hours), and ibuprofen every six to eight hours (no more than four times in 24 hours). Always dose by your child’s weight, not their age, and follow the instructions on the package. Ibuprofen is not recommended for babies under six months.
Hydration is just as important as any medication. Fever increases fluid loss, so offer water, diluted juice, or broth frequently. For babies under one year, an oral rehydration solution like Pedialyte is a better option than water or juice because it replaces both fluids and electrolytes in the right proportions. Pedialyte ice pops can work well for toddlers who resist drinking.
Dress your child in lightweight clothing and keep the room comfortable. Skip the heavy blankets, and don’t use alcohol rubs or ice baths, which can actually make things worse by causing shivering and driving the core temperature up. A lukewarm (not cold) bath can provide some relief if your child doesn’t mind it.
When 38°C Is Just a Warm Day
Normal body temperature in children fluctuates throughout the day. It tends to be lowest in the morning and highest in the late afternoon and evening. Physical activity, warm clothing, a hot bath, or even a big meal can temporarily push a reading to 37.5°C or slightly above without it being a true fever. If you get a borderline reading and your child seems perfectly fine, wait 15 to 20 minutes, make sure they haven’t just been running around or bundled up, and take the temperature again.
A single reading of exactly 38°C in an otherwise happy, active child over three months old is worth monitoring but rarely cause for alarm. Keep an eye on the trend over the next few hours. If the temperature climbs, new symptoms appear, or your child starts acting differently, that’s when it becomes more significant.