My son has always been a happy, easygoing kid. But at 4 months, Samuel was really cranky for a few days. I called the pediatrician’s office, and the nurse said it sounded like teething. That, though, didn’t seem right, so I asked to come in for a doctor’s take. I felt awkward. After all, I’d been a mom for a fraction of this nurse’s career. Who was I to second-guess someone with so much experience?

What I didn’t consider was that I’d developed my own expertise on Samuel. I could differentiate his feed-me wails from his cuddle-me whimpers and his I’m-so-sleepy sobs. Turns out, he wasn’t teething. He had an ear infection, one we were able to catch and treat early.

Indeed, parents can help docs diagnose properly. “To understand when a baby is sick, you have to understand what he’s like when he’s well–and that’s something a parent knows best,” says Paul Horowitz, MD, a pediatrician in Santa Clarita, California. Follow this guide to common childhood illnesses, how to treat them, and when to see the doctor.

This is a sign of an underlying problem rather than an illness on its own. “The body raises its temperature because the enzymes that fight infection work better at higher temperatures,” Dr. Horowitz says. A fever can be related to an ear infection, a cold, the flu, or it can be a reaction to a vaccine. Feverish kids are lethargic and irritable.

How to treat: Some parents have “fever phobia” and want to take their kids to the doctor for the slightest increase in temperature. But low-grade fevers (101 degrees or below) typically aren’t dangerous. Give baby Infants’ Tylenol, undress her, encourage her to drink fluids, and bathe her in tepid water. “Just wiping her down could lower her fever by a degree or two,” says Christopher Tolcher, MD, a pediatrician in Agoura Hills, California.

When to call the doctor: If your baby is a newborn (2 months or younger) and has even a low-grade fever, if your child is younger than 1 year and has a fever of 102 degrees or higher, if an older child has a fever of 104 degrees or higher, or if the fever (even a low-grade one) lasts more than three days. Drastic changes in behavior–such as your child’s becoming very lethargic–are also cause for concern.

The Common Cold
‘Tis the season for sniffling. Young children get six to eight colds a year, primarily during fall and winter. Symptoms (a stuffy or runny nose and sneezing, coughing, and sometimes a fever) usually build for two to three days, peak for three to five, and then subside.

How to treat: Avoid cough or cold meds, but give him Infants’ Tylenol for fever. Dry air worsens congestion, so run a humidifier in baby’s room while he sleeps. You can also drain his sinuses by elevating his head. Place books or pillows under the mattress while he sleeps; don’t put pillows directly under his head. If he’s not drinking lots of breast milk or formula, give him water or an electrolyte drink, like Pedialyte.

When to call the doctor: If your sniffling baby is a newborn, or if he has a high fever.

The Flu
This very contagious virus travels quickly through day cares and families. An infected baby will be cranky and will lose interest in playing or eating. Then she’ll develop a fever followed by a runny or stuffy nose and a cough. A flu-related fever can last three to seven days, and kids can continue to feel cranky for a few days after that.

How to treat: Care for your child as if she has a cold: give her plenty of liquids and watch out for severe coughing or breathing problems. To prevent a future bout, get your child vaccinated, which experts recommend for all kids over 6 months.

When to call the doctor: If baby is a newborn and sick, or if symptoms don’t improve within five days.

Respiratory Syncytial Virus (RSV)
This sounds scarier than it is. It’s a common virus affecting the lungs and breathing passages.Preemies are especially vulnerable because their airway and immune system aren’t completely developed. It generally begins like a cold does; by day three, a strong cough and wheezing-like breathing begin. Symptoms recede after a few days, but the cough can linger for up to two weeks. Kids who have a bad episode tend to develop asthma.

How to Treat: Use a humidifier, or have baby sleep in an elevated position. Also give him Infants’ Tylenol and extra fluid. Cool air can calm irritated airways: place him in front of an open fridge for a minute.

When to call the doctor: If your child is a newborn and sick, or if he has severe nonstop coughing or trouble breathing. “Notice if he’s using extra muscles to breathe,” Dr. Horowitz says. “Take off his shirt. If the spaces between his ribs get sucked in with each breath and his nostrils are flaring, call your doctor right away.”

Ear Infection
Baby body language is tricky because sleepy kids often rub their ears. But if she tugs her ears and also has a stuffy nose and a fever, an ear infection might be the culprit. Infants are especially prone to these.

How to Treat: Some infections clear up on their own. “To avoid the overuse of antibiotics, we’ve gotten less aggressive about treating ear infections,” Dr. Horowitz says. But a doctor will prescribe an antibiotic to relieve ear pain. You can also give baby Infants’ Tylenol to help her sleep.

When to call the doctor: If you suspect an infection. “The only way to diagnose is for your doctor to look in your child’s ear,” says Dallas pediatrician Sue Hubbard, MD. “One day the ear can look normal, and the next it might be infected. Give it a few days to see if symptoms improve. If they don’t, visit your doctor again.” A severe, untreated infection can lead to a ruptured eardrum, and repeat ear infections can lead to hearing loss.

Changing diapers–especially if they’re runny–is not one of parenthood’s joys. Watery and frequent bowel movements are often caused by a virus; but a bacterial infection, allergy, food intolerance, or medicine could also be to blame.

How to treat: Diarrhea usually lasts five to ten days. Dehydration is the main concern, so give baby lots of fluid. Is he also vomiting? Wait 30 minutes after he throws up to offer small, frequent doses of an electrolyte drink. Start with a tablespoon, slowly increasing the dose over time.

When to call the doctor: If your sick baby has a high fever or bloody diarrhea

Known as pinkeye, this condition makes your child’s eyes look red and puffy. It’s an inflammation of the eye’s mucous membranes and usually affects both eyes at once but sometimes starts in one eye only. The cause can be a bacterial or viral infection: yellow or green drainage signals bacterial; no tearing or pus indicates viral. Another way to differentiate: viral infections usually come with cold symptoms. Both are very contagious and spread quickly.

How to treat: A viral infection usually clears up on its own within a week. Keep baby’s eye area clean by gently washing it with warm water. If the infection is bacterial, your doctor will treat it with an antibiotic eyedrop. For either infection type, a warm compress will make your baby feel better.

When to call the doctor: As soon as symptoms appear. Consult a doctor to ensure the cause isn’t bacterial and to get antibiotics if needed.

Originally published American Baby magazine.

All content, including medical opinion and any other health-related information, is for informational purposes only and should not be considered to be a specific diagnosis or treatment plan for any individual situation. Use of this site and the information contained herein does not create a doctor-patient relationship. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.