When is RSV dangerous?
Last updated September 3, 2026.
RSV is a mild cold for most healthy people, but it turns dangerous for infants under 6 months, premature babies, older adults, and anyone with heart, lung, or immune problems. In babies it is the leading cause of bronchiolitis: watch for fast or labored breathing (tummy sucking under the ribs, grunting), breathing pauses, poor feeding or fewer wet nappies, and floppiness - blue or grey lips means urgent help now. Symptoms typically peak on days 3 to 5, so a coping baby can still worsen. Home care is fluids, smaller frequent feeds, saline nose drops - no cough medicines for little ones. Prevention exists: CDC-recommended immunization options for infants and at-risk older adults. Pymander is a free AI doctor, 24/7 by text, and can help you judge a baby's breathing.
What to do
- Watch the breathing, not the snot: rib-sucking, grunting, pauses are the danger signs.
- Track feeds and nappies: half-normal feeding or dry nappies mean fluids are failing.
- Expect the day 3 to 5 peak: do not relax too early.
- Ask about prevention: infant antibody shots and maternal vaccination protect the smallest.
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