Almost every child will catch RSV (respiratory syncytial virus) by the time they turn two; for most, it looks like a common cold. But in babies under a year, especially those under six months, RSV can move into the lower airways and become something more serious: bronchiolitis. Knowing the difference between “just a cold” and something that needs urgent care can make a real difference. Quick answer: RSV usually starts like a regular cold: runny nose, mild cough, low fever. Watch closely for the next 3–5 days: if breathing becomes fast, labored, or wheezy, if your baby is feeding poorly, or if you notice pauses in breathing, seek medical care right away. Babies under 6 months, premature babies, and those with heart or lung conditions are at the highest risk of complications. What Is RSV, and How Is It Different From Bronchiolitis? RSV is the virus. Bronchiolitis is what can happen because of that virus — inflammation and swelling of the tiny airways (bronchioles) in the lungs. RSV is by far the most common cause of bronchiolitis in babies under 2 years old. Not every baby with RSV develops bronchiolitis, but when they do, it’s the reason RSV can turn from “sounds like a cold” into a hospital visit. Early Symptoms of RSV RSV symptoms usually appear gradually, often starting mild and changing over a few days: Runny or congested nose Mild, dry cough Low-grade fever Decreased appetite or feeding less Sneezing In babies younger than 6 months, RSV can look different; sometimes the only early signs are irritability, decreased activity, poor feeding, or short pauses in breathing (apnea), without an obvious cough or fever. Warning Signs That Mean It’s Progressing to Bronchiolitis Watch closely between days 3–5 of illness; this is when RSV most often progresses in babies. Contact your pediatrician or seek urgent care if you notice: Fast or labored breathing — breathing that looks like real work, not just a stuffy nose Wheezing — a whistling sound when breathing out Chest retractions — the skin pulling in around the ribs or collarbone with each breath Nasal flaring — nostrils widening with each breath Grunting at the end of each breath Bluish tint to lips, tongue, or skin (cyanosis) — this needs emergency care immediately Pauses in breathing lasting more than 10–15 seconds Poor feeding or fewer wet diapers (signs of dehydration) Unusual lethargy — very hard to wake, or not responding normally If you see any of the last four, don’t wait — go to the ER. Who Is Most at Risk? RSV is more likely to become serious in: Babies younger than 6 months Premature babies Babies with congenital heart or chronic lung disease Babies with weakened immune systems How Is RSV Treated? There’s no specific antiviral medicine for most babies with RSV; treatment focuses on supporting your baby through it: Keep your baby well-hydrated with frequent, smaller feeds Use saline drops and gentle suctioning to clear a stuffy nose, especially before feeds A cool-mist humidifier can help with congestion Fever reducers appropriate for your baby’s age, if advised by your pediatrician In more severe cases, hospital care may include oxygen support, IV fluids, or monitoring Can RSV Be Prevented? Yes, this has changed significantly in recent years. According to the CDC, there are now two ways to protect infants from severe RSV: a maternal RSV vaccine given during weeks 32–36 of pregnancy, or an RSV antibody injection given directly to babies under 8 months old during RSV season. Ask your pediatrician which option is right for your baby. Everyday prevention still matters too: Frequent handwashing, especially before handling your baby Keeping your baby away from visibly sick people Avoiding crowded indoor spaces during peak respiratory-virus season where possible When to Call Your Pediatrician vs. When to Go to the ER Situation What to do Runny nose, mild cough, feeding normally Monitor at home, call your pediatrician if not improving in a few days Fast/labored breathing, wheezing, poor feeding Call your pediatrician the same day Bluish lips/skin, pauses in breathing, unresponsive Go to the ER immediately Related Reading Febrile Seizures in Children: A Parent’s Complete Guide Signs of Dehydration in Infants The Importance of Healthy Sleep Habits for Newborns Childhood Vaccination Schedule in the UAE: 2026 Guide Frequently Asked Questions Is RSV dangerous for all babies? No — most babies recover from RSV at home within a week or two, similar to a cold. It’s most likely to become serious in babies under 6 months, premature babies, and those with underlying heart or lung conditions. How long is RSV contagious? Most people are contagious for about a week, though infants and those with weakened immune systems can spread the virus for up to 3–4 weeks. Is there a vaccine for RSV? Yes. A maternal RSV vaccine can be given during pregnancy, and an antibody injection is available for infants — ask your pediatrician which is right for your baby. When should I take my baby to the ER for RSV? Go immediately if you notice bluish lips or skin, pauses in breathing, severe difficulty breathing, or if your baby is unusually difficult to wake. Concerned your baby might have RSV or bronchiolitis symptoms? Book an appointment with Dr. Olfa Koobar for a same-day evaluation.