For a 10-month-old, a fever is a rectal temperature of 100.4°F (38°C) or higher. That’s the standard threshold pediatricians use. However, the temperature at which you should call your doctor depends on how high it goes, how long it lasts, and how your baby is acting overall.
How to Get an Accurate Reading
For babies under 3 years old, a rectal temperature is the most reliable method. The American Academy of Pediatrics recommends a basic digital thermometer for this, not the fancy ear or forehead models. Ear (tympanic) thermometers can be unreliable in small ear canals, and forehead readings tend to be less precise. Underarm temperatures work in a pinch but typically read lower than rectal, so they can miss a low-grade fever.
To take a rectal temperature, apply a small amount of petroleum jelly to the tip of the thermometer and insert it about half an inch. Hold your baby still on their stomach or back until the thermometer beeps. If that number is 100.4°F or above, your baby has a fever.
When a Fever Needs Medical Attention
Not every fever requires a phone call. For a baby between 6 and 24 months old, the Mayo Clinic recommends calling your pediatrician when the temperature is above 100.4°F and lasts more than one day. If the fever climbs to 102°F (38.9°C) or higher rectally, that warrants a call sooner, especially if your baby seems uncomfortable or is acting differently than usual.
Beyond the number on the thermometer, pay attention to how your baby behaves. These signs mean you should contact your doctor promptly:
- Unusual sleepiness. Your baby is hard to wake up or seems floppy and limp.
- Inconsolable crying. Nothing calms them down, or the cry sounds different than normal.
- Rash. Especially one that appears suddenly, blisters, or looks infected.
- Signs of dehydration. Fewer than six wet diapers in 24 hours, a dry mouth, no tears when crying, or a sunken soft spot on the head.
If something just feels off about your baby, that’s reason enough to call. Parents notice subtle changes in behavior that no thermometer can capture.
Why Babies Get Fevers
A fever is your baby’s immune system responding to an infection, most commonly a virus. At 10 months, babies are increasingly mobile, putting objects in their mouths, and their immune systems are still learning. Ear infections, upper respiratory viruses, and stomach bugs are among the most common culprits. Teething can cause a very slight rise in temperature, but it doesn’t cause a true fever above 100.4°F. If your teething baby has a real fever, something else is going on.
Keeping Your Baby Comfortable
The goal of treating a fever at home isn’t necessarily to make the number disappear. It’s to keep your baby comfortable and hydrated while their body fights off whatever caused it.
Dress your baby in one layer of lightweight clothing. It’s tempting to bundle them up when they have the chills, but extra blankets and layers can trap heat and push the fever higher. One light blanket for sleep is enough.
Fluids are critical. Offer breast milk or formula frequently. If your baby is vomiting, a pediatric electrolyte solution like Pedialyte helps replace lost fluids and minerals. Avoid fruit juice. Watch diaper output closely: fewer than six wet diapers in a day signals mild dehydration. If that drops to just one or two wet diapers, along with sunken eyes, cool or discolored hands and feet, or wrinkled skin, that’s severe dehydration and needs immediate medical attention.
Fever-Reducing Medication
At 10 months old, your baby can safely take both acetaminophen (Tylenol) and ibuprofen (Motrin, Advil). The correct dose is always based on your baby’s weight, not their age. This is important because babies of the same age can vary significantly in size.
For a baby weighing 12 to 17 pounds, a typical acetaminophen dose is 2.5 mL of the infant liquid (80 mg). For ibuprofen, the dose at that weight is 1.25 mL of the infant drops (50 mg). If your baby weighs 18 to 23 pounds, the doses go up: 3.75 mL of acetaminophen (120 mg) and 1.875 mL of ibuprofen (75 mg). Always use the measuring syringe that comes with the medication, not a kitchen spoon.
Acetaminophen can be given every 4 to 6 hours and ibuprofen every 6 to 8 hours. Never give both at the same time unless your pediatrician specifically tells you to alternate them. And never give aspirin to a baby or child, as it’s linked to a rare but serious condition called Reye’s syndrome.
If the fever doesn’t respond to medication, or if it keeps coming back for more than three days, contact your pediatrician. A persistent fever can signal a bacterial infection that may need further evaluation.