Small Chests, Big Noises: Making Sense of Winter Coughs in Babies

It’s 10pm, the heating has clicked off, and your baby’s cough suddenly sounds different. Maybe it’s barky. Maybe there’s a wheeze. Maybe they’re just working harder to breathe than they were at teatime. Winter coughs are a normal part of baby life, but some noises deserve a closer look — and knowing which is which can save you a night of pure panic.

First, the reassuring rule

A cough on its own is rarely the thing that matters most. What matters is how your baby is breathing, feeding and behaving. You are not trying to diagnose bronchiolitis or croup at home. You are looking for a pattern: Is the breathing getting harder? Are they too breathless to feed? Are the nappies drying up? Are they alert between coughs?

If your baby is feeding reasonably, having wet nappies, and is alert and interested in you, you can usually watch and wait with advice. If your gut says something is off, trust it and ring 111 or your GP.

The two winter characters: bronchiolitis and croup

Bronchiolitis is a viral chest infection that mostly affects babies under two, and especially under one. RSV is a common cause. It usually starts like a cold — runny nose, mild cough, maybe a temperature — then breathing becomes faster and more effortful, and feeding gets harder. It often peaks around day three to five and then slowly improves. You may hear a wheeze or a wet cough, but the breathing effort matters more than the sound.

Croup is different. It causes a barking, seal-like cough, a hoarse voice, and noisy breathing on the in-breath, called stridor. It is often worse at night and can sound dramatic very quickly. Most cases are mild and improve over three to five days, but stridor at rest — the noise when your baby is calm, not just upset — needs a same-day assessment.

A simple symptom timeline

Think of this as a rough map, not a rulebook.

• Day 1–2: cold symptoms, mild cough, maybe a slightly reduced appetite.
• Day 3–5: bronchiolitis often peaks; croup may be at its noisiest at night. Breathing and feeding are the things to watch.
• Day 5–7: gradual improvement should start. Croup often settles over a few nights.
• Day 7 onwards: if feeding is still poor, breathing is still hard, or a fever keeps returning, ask for a second look.

A cough can linger for two to three weeks after a viral illness, but the direction should be towards better. If your baby is getting worse instead of slowly improving, that is your cue to seek advice.

Feeding and nappies: the quiet clues

Breathing problems show up at the breast or bottle before they show up on your face. A baby who is too breathless to feed, or who takes only a few sucks and then gives up, needs same-day advice. So does a baby who is taking less than half their usual feeds for two or more feeds in a row.

Nappies are the other quiet clue. Fewer wet nappies than usual, a dry mouth, or no tears when crying can suggest dehydration. For a newborn, use the baseline your midwife or health visitor gave you. If you are unsure, ring 111 and describe the nappies over the last 24 hours.

Breathing signs that need a same-day call

Call your GP or 111 the same day if your baby has:

• ribs or the area under the ribs sucking in with each breath
• a visible tug at the base of the neck
• nostrils flaring
• fast breathing that does not settle when they are calm
• noisy breathing at rest, especially stridor
• a temperature of 38°C or above in a baby under three months
• fewer wet nappies or poor feeding

When to call 999

Call 999 if your baby is struggling to breathe, grunting, going blue or grey around the lips, having pauses in breathing, is floppy or unresponsive, or has severe stridor and looks exhausted. Do not drive yourself if your baby is seriously struggling — call for help.

The cough that needs a second look

Most winter coughs are viral and settle with time. But ask for a second look if a cough lasts more than three weeks, if your baby vomits after coughing, if there is blood, if a fever keeps coming back, or if the cough has a whooping sound. A croup cough that keeps returning every night for more than a few nights also deserves a check.

What to pack and what to say

If you are heading to 111, an out-of-hours GP or A&E, take a breath and grab a few practical things: your red book, nappies and wipes, a feed, spare clothes, any medicines, a phone charger, and a comfort toy or blanket. Put a coat over pyjamas rather than a thick coat under a car seat harness.

When you speak to someone, keep it simple and specific:

“This is [name], [age] weeks/months. They started with a cold on [day]. Their breathing has become [faster/harder/noisier] since [time]. They are taking [number] feeds and have had [number] wet nappies in 24 hours. Their temperature was [number] at [time]. The noise sounds like [bark/wheeze/whistle] and is worse [at night/feeding]. I’m worried about [breathing/feeding].”

That gives the clinician what they need quickly. You are not expected to know the diagnosis. You are the person who knows your baby best — and noticing the change is enough.