The first time you hear your child make a noise that sounds like a seal barking, your instinct will be to panic. That is croup - a swelling of the upper airway that creates a distinctive harsh, barking cough. It sounds terrifying. In most cases, it is not dangerous, but it needs to be taken seriously.
What it looks like
Croup is most common between six months and three years. It usually starts with cold symptoms then the barking cough develops, often quite suddenly. Symptoms are almost always worse at night. You may hear stridor - a high-pitched rasping sound when breathing in.
What to do
Call 111 or get an urgent GP appointment - they can prescribe a single dose of oral dexamethasone (a steroid) which reduces airway swelling within hours. At home, sit your child upright, keep them calm (crying worsens symptoms by further narrowing the airway), offer plenty of fluids, and give paracetamol or ibuprofen for discomfort.
What not to do
Do not take your child into a steamy bathroom. The NHS no longer recommends steam inhalation for croup - there is no good evidence it helps, and hot steam carries a burn risk.
It tends to come back
Some children get croup every winter for a few years. This doesn't mean anything is wrong with their airway - it reflects the fact that their airway is still small enough for swelling to cause narrowing. Most children outgrow it by school age.