Last reviewed: November 6, 2026 · Updated to match current American Academy of Pediatrics (AAP) and CDC guidance.
Quick answer: The most common health problems in newborns and young babies are fever, jaundice, baby acne, colds and other respiratory infections such as bronchiolitis (often caused by RSV), ear infections and hand, foot and mouth disease. In a baby under 3 months, a rectal temperature of 100.4°F (38°C) or higher is an emergency: call your doctor right away, and don’t give fever medicine unless they tell you to. Vaccines, handwashing and keeping your baby away from sick people protect against many of these illnesses.
Always call your pediatrician if a new symptom shows up or something about your baby’s health seems unusual. Here are 12 conditions every new parent should know about, what they look like, and when to get help.
1) Fever
A normal temperature for a baby is about 97.5°F to 99.5°F (36.4°C to 37.5°C). A fever is a rectal temperature of 100.4°F (38°C) or higher. A rectal thermometer gives the most accurate reading in young babies.
- Under 3 months: call your doctor right away or go to the ER for any fever, even if your baby seems well. Young babies can have serious infections with few other signs. Don’t give acetaminophen unless the doctor advises it.
- 3 months and older: call your doctor if the fever is 102°F (38.9°C) or higher, lasts more than 2 to 3 days, or your baby seems very sick.
Keep offering breast milk or formula so your baby doesn’t get dehydrated, and dress them in light clothing. See our guide on how to dress a baby with a fever at night.
2) Baby Acne
Small red or white bumps on the cheeks, nose and forehead are common in the first weeks and usually clear up on their own within a few weeks to months. Wash your baby’s face gently with water, pat it dry, and avoid lotions, oils and acne creams. Call your pediatrician if the bumps look like blisters, are filled with pus, or your baby has a fever or seems unwell.
3) Jaundice
Jaundice is a yellow tint to the skin and eyes caused by a build-up of bilirubin. It’s very common in the first week because a newborn’s liver is still maturing. Mild jaundice usually fades within 1 to 2 weeks, and frequent feeding helps. Your baby’s bilirubin will be checked before you leave the hospital and at early check-ups. Call your doctor if the yellow color spreads to the belly or legs, gets deeper, lasts more than 2 weeks, or your baby is very sleepy or feeding poorly. Severe jaundice needs treatment, usually phototherapy.
4) Measles
Measles is a highly contagious virus that causes high fever, cough, runny nose, red eyes and a spreading rash. It can be very serious for babies. The MMR vaccine is usually given at 12 to 15 months, so young babies rely on the people around them being vaccinated. Call your doctor right away if you think your baby has been exposed or has symptoms. Call before you go to a clinic, so staff can prevent it spreading.
5) Mumps
Mumps is a viral infection that causes fever and painful swelling of the glands near the jaw. It’s rare in babies thanks to the MMR vaccine. Call your doctor if your baby has swelling near the jaw or ear along with fever.
6) Chickenpox
Chickenpox causes an itchy rash of fluid-filled blisters. It spreads very easily. The vaccine is given from 12 months, so keep young babies away from anyone with chickenpox or shingles. Chickenpox can be serious in newborns, so call your doctor right away if your baby develops blisters or has been exposed.
7) Influenza (Flu)
The flu causes fever, cough, runny nose and fussiness, and babies under 2 are at higher risk of complications. Babies can get the flu vaccine from 6 months of age. Before then, the best protection is for pregnant parents and everyone around the baby to get vaccinated. Call your doctor if your baby has flu symptoms, especially if they’re under 3 months, are breathing fast or hard, or aren’t feeding well.
8) Pneumonia
Pneumonia is an infection of the lungs caused by viruses or bacteria. Signs in babies include fever, cough, fast or labored breathing, grunting, and poor feeding. Pneumonia in a young baby needs a doctor’s care. Seek help right away if your baby is breathing fast, you see the skin pulling in between the ribs, or their lips look bluish.
9) Hand, Foot and Mouth Disease
This common viral illness causes fever, painful sores in the mouth, and a rash on the hands, feet and diaper area. It spreads through saliva, stool and touching contaminated objects, so wash hands and toys often. Most babies recover in 7 to 10 days. Call your doctor if your baby is under 3 months, has a fever, or is refusing to feed or has fewer wet diapers.
10) Ear Infection
Ear infections often follow a cold. Signs include fussiness, trouble sleeping, pulling at the ear, fever and fluid draining from the ear. Call your pediatrician if you suspect an ear infection. Not every ear infection needs antibiotics, but babies under 6 months usually do get treated.
11) Bronchiolitis
Bronchiolitis is a common, contagious infection of the small airways in the lungs, most often caused by RSV (respiratory syncytial virus). It starts like a cold and can lead to wheezing, coughing and trouble breathing. Because it’s caused by a virus, antibiotics don’t help. Treatment focuses on suctioning the nose, keeping your baby fed, and sometimes oxygen in the hospital. An RSV antibody shot for babies, or an RSV vaccine during pregnancy, can help protect them. Get medical help right away if your baby is breathing fast, struggling to breathe, pausing in their breathing, or not feeding well.
12) Strep Throat
Strep throat is a bacterial throat infection. It’s uncommon in babies under 2 and more common in school-age children. In babies, a strep infection may show up as fever, fussiness and a runny nose rather than a sore throat. If your baby has a fever and someone at home has strep, call your pediatrician. Strep is treated with antibiotics.
How to Protect Your Baby
- Keep up with vaccines, for your baby and for everyone around them. Ask your pediatrician about the recommended schedule, or see the CDC immunization schedule.
- Wash hands before handling your baby, and ask visitors to do the same.
- Keep sick people away from your newborn, and avoid crowds in the first few months, especially during cold and flu season.
- Breastfeed if you can. Breast milk passes on antibodies that help fight infection.
When to Call the Doctor or Get Emergency Help
- Any fever of 100.4°F (38°C) or higher in a baby under 3 months
- Fast, noisy or difficult breathing, or bluish lips
- Fewer than 3 or 4 wet diapers a day, or refusing feeds
- Being very sleepy, hard to wake or floppy
- A rash that doesn’t fade when you press on it
- Yellow skin that is spreading or getting deeper
The Bottom Line
Most newborn illnesses are mild, but young babies can get sick quickly. Any fever of 100.4°F (38°C) or higher in a baby under 3 months needs a call to the doctor right away. Vaccines, handwashing and keeping your baby away from sick people are the best ways to protect them.
This article is for general information and isn’t a substitute for medical advice. Always contact your pediatrician if you’re worried about your baby’s health.
3 Sources
Newborn Stages uses trusted sources, including government health agencies, children’s hospitals and pediatric organizations, to support the facts in our articles. Read our editorial policy to learn how we research, fact-check and keep our content accurate.
- Seattle Children’s Hospital. Fever.
- Centers for Disease Control and Prevention (CDC). Child and Adolescent Immunization Schedule by Age.
- Mayo Clinic. Infant jaundice.
