A toddler has a fever when their rectal temperature reaches 100.4°F (38°C) or higher. This is the standard threshold used by the American Academy of Pediatrics and most pediatricians. But the exact number that counts as a fever depends on how you take the temperature, because different parts of the body run at slightly different baselines.
Fever Thresholds by Measurement Method
A temperature is considered a fever when it exceeds the normal range for the method you’re using:
- Rectal: above 100.4°F (38°C)
- Oral (mouth): above 99.5°F (37.5°C)
- Armpit (axillary): above 99.1°F (37.3°C)
- Ear (tympanic): above 100.4°F (38°C)
Rectal readings are considered the most accurate for toddlers and are what your pediatrician will reference. If you take a temperature under the arm and get a borderline reading, a rectal check gives you a more reliable number.
Which Thermometer Is Most Reliable
Rectal thermometers remain the gold standard for children under three. Digital rectal thermometers are inexpensive, fast, and give a consistent reading. Ear thermometers are convenient but can be thrown off by earwax or improper positioning in a toddler’s small ear canal.
Non-contact infrared (forehead) thermometers are popular because they’re quick and don’t require a fussy toddler to hold still. However, a study of 200 children ages one month to four years found that forehead thermometers overestimated temperatures in kids who weren’t feverish and underestimated temperatures in kids who actually had fevers. The correlation with rectal readings was weak enough that researchers cautioned against relying on them as a primary tool. If your forehead thermometer gives a reading close to the fever threshold, it’s worth confirming with a rectal or oral check.
What a Low-Grade Fever Looks Like
A rectal temperature between 99°F and 100.4°F is sometimes called a low-grade fever, though technically it still falls within normal range. Normal body temperature fluctuates throughout the day, running lower in the morning and slightly higher in the late afternoon. Activity, warm clothing, and a hot bath can all push it up temporarily without meaning your child is sick.
True fevers in toddlers are almost always caused by the immune system fighting an infection, most commonly a virus like a cold, flu, or stomach bug. Bacterial infections (ear infections, urinary tract infections, strep throat) can also be the cause, and these typically need treatment.
Does Teething Cause Fever?
This is one of the most common questions parents have. Research shows that teething can raise a baby’s temperature slightly, but not enough to produce a true fever. In one study tracking infants around tooth eruption, more children had temperatures above 99.5°F on the day a tooth broke through, but the temperatures generally stayed below the 100.4°F fever threshold. If your toddler has a temperature of 101°F or higher, something other than teething is likely responsible, even if they’re also drooling and chewing on everything.
Managing a Toddler’s Fever at Home
Fever itself isn’t dangerous in most cases. It’s a sign that your child’s immune system is working. The goal of treatment isn’t to eliminate the fever entirely but to keep your child comfortable enough to rest and drink fluids.
Acetaminophen (Tylenol) can be given every four to six hours, with no more than five doses in 24 hours. Ibuprofen (Motrin, Advil) can be given every six to eight hours, with no more than four doses in 24 hours. Ibuprofen is only appropriate for children six months and older. Both medications are dosed by weight, not age, so check the packaging or ask your pharmacist if you’re unsure. Never give aspirin to a child.
Keep your toddler in light clothing and offer fluids frequently. Diapers that are drier than usual are a sign of dehydration. A child who hasn’t had a wet diaper in three hours during illness needs closer attention. Small, frequent sips of water, breast milk, formula, or an electrolyte solution are more effective than trying to get them to drink a large amount at once.
Febrile Seizures
About 2 to 5 percent of children between six months and five years will experience a febrile seizure, a convulsion triggered by fever. These are frightening to witness but are typically harmless and don’t cause brain damage or epilepsy. They can happen even with a low-grade fever. The speed of temperature rise seems to matter more than how high the fever gets, which is why seizures sometimes occur before a parent even realizes their child is feverish. If your toddler has a seizure, lay them on their side, don’t put anything in their mouth, and time it. Most last less than a minute or two.
Signs That Need Medical Attention
How your toddler looks and acts matters more than the number on the thermometer. A child with a 102°F fever who is drinking, playing between rest periods, and making eye contact is generally less concerning than a child with a 100.5°F fever who is limp and unresponsive.
Call your pediatrician if the fever lasts more than 24 hours in a child under two, or more than 72 hours in a child two or older. Also contact them if your toddler is hard to wake up or seems disoriented, is crying inconsolably in a way that sounds different from their normal cry, or is quiet and listless even when the fever comes down with medication.
A rash that doesn’t fade when you press a glass against it is a red flag for a serious blood infection. On darker skin tones, check the palms of the hands and soles of the feet where this kind of rash may be easier to spot. This warrants emergency care immediately.