A baby has a fever when their rectal temperature reaches 100.4°F (38°C) or higher. For most babies older than 3 months, you can bring a fever down at home using a combination of lightweight clothing, extra fluids, and age-appropriate fever-reducing medication. Younger babies with any fever need prompt medical evaluation, so age is the first thing to consider before you start treating at home.
Check the Temperature Accurately
For babies 3 and under, a rectal thermometer gives the most accurate reading because it measures internal body temperature. Armpit readings are the least reliable option. Digital ear thermometers work well for babies 6 months and older, and forehead thermometers can be used starting at 3 months, though they’re less precise than rectal readings.
If you’re unsure whether your baby actually has a fever, take a rectal reading before deciding on next steps. A normal rectal temperature runs between 97°F and 100.3°F, so anything at or above 100.4°F counts as a true fever.
Age Determines Your First Move
A fever in a newborn is handled very differently than a fever in a 9-month-old. The American Academy of Pediatrics considers any fever at or above 100.4°F in babies 8 to 60 days old serious enough to warrant medical evaluation, even if the baby looks fine. Babies this young don’t have mature immune systems, and a fever can signal an infection that needs testing.
Here’s the general breakdown:
- Under 3 months: Any rectal temperature of 100.4°F or higher warrants a call to your pediatrician right away, regardless of how the baby seems.
- 3 to 6 months: You can begin home treatment, but contact your doctor if the fever reaches 102°F or if your baby seems unusually irritable or sleepy.
- Over 6 months: Home treatment is generally appropriate. Focus on comfort and watch for warning signs.
Keep Your Baby Cool and Comfortable
Before reaching for medication, simple changes can help bring a fever down or at least keep your baby more comfortable. Dress your baby in lightweight clothing and cover them with a light sheet or blanket rather than bundling them up. Overdressing traps heat and can push the temperature higher.
Keep the room at a comfortable temperature. You don’t need to make it cold, just avoid a warm or stuffy environment. Never use rubbing alcohol on your baby’s skin or place them in a cold bath. Both can cause dangerous drops in body temperature or other harmful reactions. A lukewarm sponge bath is a safer option if you want to use water to cool them down, but it’s not necessary if medication is working.
Push Fluids to Prevent Dehydration
Fever speeds up fluid loss, and babies dehydrate faster than adults. Offer breast milk or formula more frequently than usual. Babies should not be given fruit juice during a fever. If your baby is vomiting and can’t keep milk down, an electrolyte drink like Pedialyte can help replace lost fluids.
Watch for signs that your baby is getting dehydrated: crying without tears, no wet diapers for 8 hours or longer, a dry mouth, or a sunken soft spot on the top of their head. Any of these signs mean you should call your pediatrician.
When to Use Fever-Reducing Medication
Medication isn’t always necessary. A mild fever is your baby’s immune system fighting off an infection, and bringing the number down doesn’t make the illness go away faster. The real goal is comfort. If your baby is fussy, not sleeping well, or clearly miserable, medication can help them feel better.
You have two options: acetaminophen (Tylenol) and ibuprofen (Advil or Motrin). They have different age cutoffs and dosing schedules.
Acetaminophen
Acetaminophen can be given to babies 8 weeks and older. Dose it based on your baby’s weight, not their age. You can give it every 4 to 6 hours as needed, but no more than 5 doses in a 24-hour period. If you’re unsure of the right dose, your pediatrician’s office can walk you through it over the phone.
Ibuprofen
Ibuprofen is not safe for babies under 6 months old unless a doctor specifically directs you to use it. For babies 6 months and older, give it every 6 to 8 hours as needed, with a maximum of 4 doses in 24 hours. Like acetaminophen, the dose should be based on weight.
Alternating the Two
It’s best to stick with one medication at a time. If a single medication isn’t bringing the fever down or making your baby more comfortable, you can use both acetaminophen and ibuprofen together. They’re safe to give at the same time or close together. Just track each one separately: acetaminophen no more than once every 4 hours, ibuprofen no more than once every 6 hours. Writing down the time and type of each dose helps avoid accidentally doubling up.
Signs That Need Medical Attention
Most fevers in babies over 3 months resolve on their own within a few days. But certain symptoms alongside a fever signal something more serious.
Call your pediatrician if your baby:
- Won’t eat: Missing two or more feedings in a row or eating very poorly.
- Is unusually sleepy: Sleeping much more than normal, hard to wake up, or seeming floppy or limp.
- Develops a rash: Especially one that appears suddenly, blisters, or looks infected.
- Shows signs of dehydration: No tears when crying, no wet diapers for 8 hours, dry mouth, or a sunken soft spot.
- Is vomiting forcefully: Not just normal spit-up, but liquid shooting out rather than dribbling. Also call if your baby hasn’t kept liquids down for 8 hours.
- Has breathing trouble: Fast or labored breathing, or a cough paired with difficulty getting air.
Seek emergency care if your baby has a head injury with changes in consciousness, is extremely difficult to console, or shows any sudden change in responsiveness. Trust your instincts. If something feels off about how your baby looks or acts, that’s reason enough to call.
How Long a Fever Typically Lasts
Most fevers caused by common viral infections last 2 to 3 days. Some can stretch to 5 days. The fever often comes and goes during that window, spiking higher in the evening and dropping in the morning. This pattern is normal and doesn’t mean the illness is getting worse.
If your baby’s fever lasts longer than 3 days, or if it goes away and then returns after a day or two without fever, that’s worth a call to your doctor. A returning fever can sometimes indicate a secondary infection that developed after the original illness.