Updated June 2026 · 90-second read + video
Most RSV looks like a bad cold — lots of mucus, cough, sometimes fever — and clears at home in a week. What turns it serious is working to breathe (retractions, flaring, grunting), pauses in breathing, or not feeding enough to make wet diapers. That's when to be seen.
The 90-second version
The signs we watch for in the ICU, and the ones you can catch at home first.
What to watch for
RSV can look mild one hour and worse the next. Watch day 3–5 closely.
Retractions, nasal flaring, grunting, or fast breathing at rest.
Too breathless to feed, or fewer than 1 wet diaper every 6–8 hours.
Pauses over 15–20 seconds, or any blue around the lips.
RSV is the illness I want every parent to know by name. It's incredibly common, usually fine, and occasionally it's the reason a baby ends up in my ICU. Knowing what to watch for is half the battle.
The way I'd explain it over coffee. Tap any question.
Respiratory Syncytial Virus is a common winter virus. In older kids and adults it's just a cold. In babies — especially under 6 months — it can inflame and plug the smallest airways (bronchiolitis), making it hard to breathe and feed.
RSV peaks in the middle of the illness, not at the start. A baby who looks fine on day 1 can look much worse by day 4 as mucus builds up. That's normal — but it's exactly when to watch breathing closely.
Mostly supportive: suctioning the nose, small frequent feeds, fluids, and time. The new monoclonal antibody (Beyfortus / nirsevimab) and maternal RSV vaccine are for prevention, not active treatment.
Quick answers to what parents ask most.
Usually 1–2 weeks total. Worst day 3–5, improving slowly after day 7. A lingering cough can stick around 2–4 weeks — that part is normal.
Yes — RSV immunity is short-lived. Most kids have RSV more than once, but the second time is usually milder.
It's a long-acting antibody shot that prevents severe RSV in babies. Strongly recommended for infants under 8 months entering their first RSV season — talk to your pediatrician.
Typical timeline
Warning signs
Keep it on your phone
The whole guide, pocket-sized. Save it to your phone and send it to your partner, your parents, whoever's watching the baby tonight.
Questions
Have a question about this topic? I read every one and answer as many as I can, sometimes right here, sometimes in a video.
Questions and answers are for general education only and do not create a doctor-patient relationship. For medical advice specific to your child, always consult your pediatrician.
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