Bronchiolitis often begins like a cold, then affects breathing and feeding. Symptoms can be at their worst around days 3 to 5, but every baby’s course is different. Here is what to watch for and when to seek help.
General education, not a diagnosis. Do not wait for a stage in the guide if your child is getting worse.
Bronchiolitis is a viral chest infection in babies and children under 2. It often starts with sneezing, a runny or blocked nose, and a slightly raised temperature. These early signs can look much like an ordinary cold; by themselves, they do not tell you how the illness will develop. Respiratory syncytial virus, or RSV, is a common cause, and viruses spread easily through coughs and sneezes. The timeline is a guide to a possible pattern, not a set of deadlines. [1]
As the illness develops, a baby may cough, breathe more quickly, feed less easily, or make wheezing or crackling sounds while breathing. Irritability can also occur. Notice the whole picture: breathing effort, feeding, wet nappies, temperature and how alert your baby seems. Symptoms can overlap rather than arrive in a neat order. A noisy breath alone does not establish how serious the illness is; changes in effort, pauses, colour or alertness matter too. [1]
Symptoms are usually worst between days 3 and 5. That is a common pattern, not a promise about any one baby, and it does not mean you should wait if your baby is worsening or showing warning signs. A cold that is getting worse, much less feeding, dehydration signs, unusual tiredness or a temperature meeting the thresholds below calls for urgent medical advice. Babies under 6 months and some babies with particular health or birth histories have a higher risk of becoming seriously ill. [1]
Bronchiolitis usually gets better on its own, and the cough usually improves within 3 weeks. This is a usual course, not a guaranteed recovery date; symptoms and needs differ. Keep paying attention to breathing, feeds and wet nappies while the cough settles. There is no specific treatment for bronchiolitis, and some children need hospital care. If your baby seems seriously unwell, trust your judgement and seek help rather than relying on the timeline. [1]
Assessment may include asking when symptoms began and whether a cold is worsening, how breathing looks and sounds, and how much your baby is feeding. They may also want to know about wet nappies, temperature, alertness and whether your baby seems unlike themselves. These details help guide assessment; this guide cannot diagnose bronchiolitis or judge your baby’s breathing from a description. [1]
Tell the clinician your baby’s age and whether they were born very prematurely, have a heart or lung condition, or have a weakened immune system. Babies under 6 months and children with these factors have a higher risk of serious illness. A clinician can assess the current symptoms in that context. A baby’s risk history does not, on its own, say how severe today’s illness is. [1]
Bronchiolitis is different from bronchitis. Bronchitis causes a cough with lots of mucus and can affect people of all ages. Wheezing or crackling can occur in bronchiolitis, but a sound alone is not enough to confirm the cause or assess seriousness. If breathing is difficult, there are pauses, or your baby looks blue or grey, act urgently rather than trying to identify the illness at home. [1]
Sneezing, a runny or blocked nose and a slightly high temperature can be early bronchiolitis signs. Ask for urgent medical advice if your baby has had a cold and it is getting worse, or if feeding has dropped markedly. A clinician can ask how symptoms have changed over time; the early resemblance to a cold does not rule out bronchiolitis. [1]
A clinician may ask about faster breathing, wheezing or crackling, feeding difficulty, and whether your baby is taking much less than usual. They may ask when the last wet nappy was: a dry nappy for 12 hours or more, or other dehydration signs, needs urgent advice. These questions help assess the situation; no single answer here can diagnose the cause. [1]
Tell the clinician your baby’s measured temperature, how alert they are, and whether they feel unusually hot or cold or are shivering. Urgent advice is needed for a temperature of 38°C or higher in a baby under 3 months, or 39°C or higher in a baby older than 3 months. Age, very premature birth, heart or lung conditions, and a weakened immune system are also relevant to assessment. [1]
Call emergency services now if your baby is having difficulty breathing. Signs can include grunting, the tummy sucking in under the ribs, or very quick breathing. Get emergency help if there are pauses in breathing, or the skin, tongue or lips look blue or grey. On brown or black skin, colour change may be easier to see on the palms, soles, lips, gums or inside the eyelids. [1]
Call emergency services now if your baby is floppy and will not wake up or stay awake. Do not wait for the cough or other symptoms to change. If you feel your child is seriously unwell, trust your judgement and seek emergency help. [1]
Seek urgent medical advice if a cold is getting worse, your baby is feeding much less than normal, or there has been a dry nappy for 12 hours or more or other signs of dehydration. Also seek urgent advice if your baby is very tired, irritable, not themselves, or you are worried. These signs deserve prompt attention even if breathing does not look like an emergency. [1]
Seek urgent medical advice for a temperature of 38°C or higher if your baby is under 3 months, or 39°C or higher if older than 3 months. Also seek advice if your baby feels hotter than usual on the back or chest, is sweaty, has a very high or low temperature, feels hot or cold to the touch, or is shivering. Follow local urgent-care arrangements; emergency breathing or alertness signs need emergency services now. [1]
AI-assisted draft based on the sources below. Stages may overlap and duration varies.
Clinical and language review pending.