A 9-month-old has a fever when their rectal or forehead temperature reaches 100.4°F (38.0°C) or higher. If your baby’s temperature has crossed that threshold, the good news is that at this age, fever is almost always a sign that their immune system is doing its job fighting off a common infection. Your main tasks are keeping them comfortable, watching for warning signs, and knowing when to call the pediatrician.
How to Get an Accurate Temperature
At 9 months old, you have several reliable options. A rectal thermometer remains the most accurate choice for children under 3. Forehead (temporal artery) thermometers are nearly as accurate and much easier to use. Ear thermometers work well for babies older than 6 months, so your 9-month-old is in the clear for that method too.
Armpit readings are the least reliable. If you get an armpit reading of 99°F (37.2°C) or higher, that counts as a fever, but you may want to confirm with a rectal or forehead reading for a more precise number. When using a rectal thermometer, lubricate the tip, insert it about half an inch, and hold it in place for the time specified by the manufacturer.
Keeping Your Baby Comfortable at Home
Dress your baby in light, comfortable clothing. One of the most common mistakes is bundling a feverish baby in extra layers, which traps heat and can push their temperature higher. A single layer of pajamas is usually enough. If they’re shivering, a light blanket is fine, but remove it once the shivering stops.
Keep the room at a comfortable temperature rather than cranking the heat or blasting the air conditioning. You can offer a lukewarm (not cold) sponge bath if your baby seems very uncomfortable, but there’s no need to force it. Cold water or alcohol rubs can cause shivering, which actually raises body temperature.
Fever-Reducing Medication
Both acetaminophen (Tylenol) and ibuprofen (Motrin, Advil) are options for a 9-month-old. Ibuprofen is approved for babies 6 months and older, so your child can take either one. Always dose by your baby’s weight, not their age. The liquid syrup form of acetaminophen typically comes as 160 mg per 5 mL, and your baby’s weight will determine the correct amount. Check the packaging or call your pediatrician’s office if you’re unsure about the right dose.
A 2024 meta-analysis published by the American Academy of Pediatrics found that alternating between acetaminophen and ibuprofen is more effective at bringing down a fever than using either medication alone. At the 4- and 6-hour marks, children who received alternating doses were roughly five times more likely to be fever-free compared to those given only acetaminophen. Both approaches showed similar safety profiles when used at appropriate doses in the short term. If you choose to alternate, keep a written log of which medication you gave and when, because mixing up doses is easy when you’re sleep-deprived.
Never give aspirin to an infant. It’s linked to a rare but serious condition called Reye’s syndrome in children.
Fluids and Feeding
Fever increases fluid loss, so your baby needs extra liquids. Offer breast milk, formula, or small amounts of water more frequently than usual. Don’t worry if their appetite for solid foods drops. That’s normal and temporary. The priority is fluids, not food.
Watch for signs of dehydration: fewer than the usual number of wet diapers (or no wet diaper for three hours), a dry mouth, no tears when crying, sunken eyes, or skin that stays pinched up instead of flattening back immediately. A sunken soft spot on top of the head is another red flag. If you notice these signs, contact your pediatrician right away.
When to Call Your Pediatrician
For a baby under 2 years old, call the pediatrician if the fever lasts longer than 24 hours, even if your child doesn’t seem very sick. That timeline is shorter than for older children, so don’t wait it out for days.
Call sooner if your baby:
- Is crying inconsolably and can’t be soothed
- Is unusually sleepy or difficult to wake up
- Has a rash accompanying the fever
- Has severe vomiting or diarrhea
- Shows signs of a stiff neck or seems to be in significant pain
- Has a weakened immune system or is on medications that suppress immunity
- Is not up to date on vaccines
- Looks or acts very sick in a way that concerns you, even if you can’t pinpoint why
Trust your instincts here. You know your baby’s normal behavior better than anyone. A baby who is still making eye contact, taking fluids, and having periods of playfulness between fussy spells is generally in good shape. A baby who is limp, unresponsive, or just “not right” warrants a call regardless of the number on the thermometer.
What to Do if Your Baby Has a Seizure
Febrile seizures happen in about 2 to 5 percent of children between 6 months and 5 years. They’re triggered by the rapid rise in temperature, not necessarily by how high the fever gets. Seeing your baby seize is terrifying, but febrile seizures are almost always harmless and don’t cause lasting damage.
Signs include stiffening or shaking of the arms and legs (on one or both sides), eyes rolling back, changes in breathing, or a bluish color around the lips. Sometimes a child loses consciousness without any visible shaking.
If it happens, gently place your baby on the floor on their side. Move away any nearby objects or furniture. Loosen clothing around their head and neck. Do not put anything in their mouth. Despite the old myth, a child cannot choke on their tongue during a seizure, and placing objects in their mouth can block their airway. Try to note the time so you know how long it lasts.
Call 911 if the seizure lasts longer than five minutes, if your baby turns blue, if seizures repeat, or if your baby doesn’t return to normal fairly quickly afterward. For a first febrile seizure of any length, call your pediatrician once it’s over so they can evaluate your child.
What the Fever Number Actually Tells You
Parents often focus on the exact temperature, but how your baby acts matters more than the number. A baby with a 102°F fever who is drinking, wetting diapers, and occasionally smiling is in a better place than a baby with 100.5°F who is listless and refusing all fluids. Fever-reducing medication won’t always bring the temperature back to normal, and that’s okay. The goal is comfort, not a perfect reading. If medication brings the fever down by a degree or two and your baby perks up enough to drink and rest, it’s doing its job.