Croup is a common childhood condition that affects the upper part of the respiratory system – the trachea (windpipe), bronchi and larynx (voice box). It causes noisy breathing, a barking cough and sometimes a hoarse voice.

Occasionally, severe croup can cause breathing difficulties, which may require a short stay in hospital. In most cases, however, croup gets better without needing any treatment.

What causes croup?

There are two kinds of croup:

  • „„Viral croup (laryngotracheitis) – this is the most common type, caused by a viral infection.
  • „„Spasmodic croup – less common and caused by an allergic reaction, this type usually comes and goes in short episodes.

Croup tends to affect young children aged between six months and three years, although it can sometimes affect older children. Boys tend to develop croup more often than girls, although we do not understand why this is the case. Croup is most common in autumn and winter, when there are more viruses present in the atmosphere.

What are the signs and symptoms of croup?

Initially, the symptoms of croup are similar to those of the common cold – that is, a sore throat, runny nose, raised temperature and a cough. The characteristic symptoms of croup develop a few days later. The child will develop a barking cough, hoarse voice and noisy breathing (stridor). The symptoms tend to be worse at night. They also worsen when the child cries or is upset.

How is croup diagnosed?

Croup can be diagnosed by a family doctor (GP) who will take a medical history, check for the symptoms and look in the child’s throat. They will usually take the child’s temperature to see if it is higher than usual. Occasionally, they may take a throat swab to identify the virus causing croup but in many cases, the symptoms have cleared up before the virus has been identified. Identifying the virus is not essential to diagnose croup but may help doctors monitor viruses circulating in the population.

How is croup treated?

In many cases, croup gets better without treatment. Keeping the child in an upright position can ease their coughing. Their symptoms will worsen when upset or crying so plenty of cuddles and comfort can help. If children run a high temperature, it can be brought down using medication, for instance, paracetamol or ibuprofen, but a pharmacist or doctor should be consulted. There is also a risk of dehydration, so the child should drink plenty of fluids.

In the past, steam has been used to help the symptoms of croup, but there is little evidence that it is successful. If the child is taken into a steamy atmosphere, for instance the bathroom, be extremely careful that the child does not come into contact with steam or hot water to avoid scalding.

As croup is caused by a virus, antibiotics will not be helpful as these only work against bacterial infections. Likewise, cough mixtures will not ease the child’s cough. In some cases, the breathing difficulties are severe enough to need a short stay in hospital, sometimes with steroid medicines to reduce the swollen airway and extra oxygen if their blood levels are low.

What happens next?

Most children are clear of croup symptoms within 48 hours and have no lasting effects of the condition. Occasionally, a child may develop a secondary bacterial infection such as pneumonia or a middle ear infection following croup as viral illnesses can increase the risk of developing a bacterial infection but this is rare.

Compiled by: 
The Critical Care and Cardiorespiratory team in collaboration with the Child and Family Information Group
Last review date: 
February 2015