A baby starts with what looks like a cold, then breathes faster and wheezes — and the word “bronchiolitis” comes up. The NHS describes bronchiolitis as a common chest infection that affects babies and children under 2. It’s usually mild but can be serious, and babies under 6 months are at higher risk of serious illness. Symptoms are usually worst between days 3 and 5, and the cough usually gets better in 3 weeks. It’s usually caused by RSV, and almost all children catch it before age 2. Difficulty breathing, pauses in breathing or blue lips mean call 999. This sets out the NHS page “Bronchiolitis”.
1. A common chest infection under 2; worst on days 3 to 5; the cough usually gets better in 3 weeks.
2. Keep them upright when awake, smaller more frequent feeds, check overnight. Paracetamol over 2 months, ibuprofen over 3 months — not both at once.
3. Grunting, tummy sucking under the ribs, pauses in breathing, blue lips, won’t wake: call 999.
Symptoms and course — NHS
| When | What the NHS says | Worth noting (our gloss) |
|---|---|---|
| At first | Like a cold — sneezing, runny or blocked nose, slightly high temperature | Hard to tell from a cold at first |
| Later | Cough, faster breathing, trouble feeding, wheezing or crackling, irritability | — |
| Worst | Usually days 3 to 5 | Check more often then |
| Cough | Usually better in 3 weeks | — |
RSV symptoms and how long it spreads are in RSV symptoms, from the CDC.
Looking after your child at home — NHS
| Type | What the NHS says | Worth noting (our gloss) |
|---|---|---|
| Do | If distressed, children’s paracetamol (over 2 months) or ibuprofen (over 3 months) | Not both at the same time |
| Do | Keep them upright when awake; check regularly, including overnight | — |
| Do | Plenty of fluids; smaller, more frequent feeds for babies | — |
| Don’t | Smoke around the child | — |
| Don’t | Sponge with cool water or strip off clothes to lower a temperature | — |
| Don’t | Give aspirin to a child under 16 | — |
General advice on baby fevers is in baby fever, and baby coughs and colds in baby cough and cold. The page doesn’t mention saline drops.
Call 999 — NHS
- Difficulty breathing — grunting, the tummy sucking under the ribs, fast breathing
- Pauses in breathing
- Skin, tongue or lips blue or grey
- Floppy and won’t wake or stay awake
Urgent GP or 111 — NHS
| When | Number | Worth noting (our gloss) |
|---|---|---|
| A cold that is getting worse | — | — |
| Feeding or eating much less than normal | — | No “half” figure on this page |
| No wet nappy or other signs of dehydration | 12 hours or more | — |
| Temperature — under 3 months | 38C | — |
| Temperature — over 3 months | 39C or higher | — |
| Unusually hot or sweaty; very high or low temperature; shivering | — | — |
| Very tired, irritable or not themselves; any worry | — | A parent’s worry counts |
In the UK this is the urgent GP or 111 list. In Korea, read it as a guide for when to find a paediatrician or night clinic (our view). Finding an open emergency room is covered in emergency rooms on holidays.
Checklist
- ☐ Under 2, breathing faster and wheezing after a cold?
- ☐ Check often on days 3 to 5, overnight too
- ☐ Small, frequent feeds; count wet nappies — none for 12 hours: get help
- ☐ 38C under 3 months, 39C or higher over 3 months: get help
- ☐ Pauses in breathing, blue lips, won’t wake: 999
Questions that remain
Are antibiotics needed?
The page doesn’t discuss antibiotics; it says bronchiolitis is usually caused by a virus (RSV).
What if the cough lasts more than 3 weeks?
The NHS says the cough usually gets better in 3 weeks. Longer than that, or anything on the lists above, reads as a reason to get checked (our reading).
If a barking cough and hoarse voice stand out more than wheezing, the NHS has separate croup advice (croup).
Sources
- NHS — Bronchiolitis — source (page shows: reviewed 19 February 2026, next review 19 February 2029; checked 14 October 2026). Under 2, under 6 months, days 3 to 5, 3 weeks, 2 and 3 months, under 16, 999 signs, 12 hours, 38C and 39C, RSV.
- Not read. Korean agency guidance on bronchiolitis.
- What we added. The “worth noting” column.
Where else to check
- A paediatrician — if breathing is fast or feeding is poor.
Written on 14 October 2026. The content is from the NHS; the glosses are ours. It does not replace diagnosis or treatment.
