Fast facts

  • Croup is a childhood illness that causes a child to cough and breathe heavily and noisily, especially at night.
  • Croup is caused by an inflammation of the voice box and windpipe. This inflammation is triggered by a viral infection.
  • Some children with croup can become seriously unwell. If symptoms are severe, or breathing difficulties occur, you should seek urgent medical attention.

What is croup?

Croup is a common childhood condition characterised by a barking cough and noisy breathing. It occurs when an infection with a virus causes inflammation and swelling of the voice box (larynx) and windpipe (trachea), making it harder to breathe. Symptoms are usually more noticeable at night.

The condition is most common in children under five years of age, because their small, soft windpipes are more likely to be affected by swelling. As children grow, their windpipes become bigger, stronger and better able to cope with infection. However, croup does sometimes occur in children up to about 15 years of age. It may also come back several times in some children who are prone to croup.

Causes

Croup is usually caused by infection with a virus, particularly the family of parainfluenza viruses. However, several other viruses can also cause croup, including influenza virus (flu), respiratory syncytial virus (RSV), rubeola virus (which also causes measles) and adenovirus.

These viruses infect the nose and throat first, before moving further down the airway into the voice box and windpipe. In turn, infection triggers inflammation, swelling and increased production of mucus, which partly blocks the upper windpipe.

Under these conditions, taking a breath can cause the windpipe to collapse, narrowing the space available for air to enter the lungs. Air vibrates as it passes through the narrowed windpipe, causing the harsh, high-pitched noise (stridor) when breathing in.

Croup is spread from person to person by breathing in droplets of fluid that have been sneezed or coughed by an infected person. The viruses that cause croup can also be passed on by touching the skin of someone who is already infected, or by sharing contaminated towels, bed linen or clothing.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Parainfluenza

An illness caused by viruses similar to influenza viruses. Can cause respiratory infections, particularly in children.

Respiratory syncytial virus

A common virus that causes mild cold-like symptoms in adults and healthy older children. It can cause more serious lung and airway infections in infants or people with serious illnesses.

Influenza virus

The virus that causes the flu, an infectious disease of the respiratory system.

Rubeola virus

The virus that commonly causes measles, an infectious disease that causes a fever, sore throat, runny nose and a distinctive red skin rash.

Risk factors

Risk factors that increase the likelihood of developing croup include:

  • Age - children under the age of five years are at most risk;
  • Season - exposure to colds and viruses is higher in late autumn through early spring;
  • A personal or family history of croup, and;
  • Being prone to upper respiratory tract infections.

Upper respiratory tract

The nose, sinuses, larynx and trachea parts of the respiratory tract which function to carry air to and from the lungs.

Signs and symptoms

Croup often starts with symptoms of a common cold, including a cough, runny nose and mild fever. The characteristic barking cough and noisy breathing usually develop at night, often several days after the initial cold symptoms. The cough usually sounds like a harsh, high-pitched whistling or crowing sound when taking a breath in.

Other general symptoms may include:

  • A hoarse voice;
  • Increased mucus production;
  • Reduced hunger;
  • General feeling of being unwell, and;
  • Difficulties breathing.

In most cases, the cough and breathing symptoms become worse at night. During the day, a milder cough and cold may be present, but generally children do not feel as bad.

The symptoms of croup are typically worse on the second or third day of the illness.

Croup causes a general feeling of being unwell. 

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Methods for diagnosis

Your doctor will most likely diagnose croup by observing your child's symptoms, particularly any coughing or breathing noises. This may involve listening to the chest with a stethoscope or taking your child's temperature.

Types of treatment

Treatment for croup will depend on the seriousness of your child's symptoms. Possible options include:

Self care

In mild cases, croup may be managed at home if you and your child are relaxed and comfortable. To relieve pain and fever, your doctor may suggest over-the-counter medications, such as liquid paracetamol or ibuprofen. Your doctor may also recommend plenty of water and rest to naturally boost your child's immune response to infection.

As the symptoms of croup are often made worse by stress and crying, you may also find it helpful to sit your child upright on your lap, while offering reassurance or a favourite toy.

In the past, providing an environment of moist, warm air, such as with warm showers or hot-steam humidifiers, was commonly recommended to treat croup. However, they are no longer recommended as research does not show any improvement with such environments, and instances of scalding and burns are increased.

Medications

If your child is distressed or having breathing difficulties, your doctor may prescribe one or more of the following medications:

Corticosteroids

For mild to moderate cases of croup, your doctor will most likely prescribe an oral corticosteroid, such as prednisolone. In severe cases, these medications may be injected directly into a muscle or vein. Corticosteroids work by reducing general inflammation throughout the body, including the voice box and windpipe. Symptoms usually ease within several hours of treatment.

Hospital treatment

Some children with severe symptoms may be admitted to hospital for observation and further treatment. In hospital, oxygen may be given through a mask if your child is distressed or finding it hard to breathe.

For severe or potentially life-threatening cases of croup, your child may be given adrenaline as an inhaled mist. This treatment reduces inflammation of the voice box and larynx within 30 minutes and lasts up to two hours. Adrenaline is administered with a nebuliser, usually in a hospital setting.

In very rare cases, a tube may be inserted into your child's nose or mouth to help with breathing. This procedure, known as intubation, is conducted under general anaesthetic to reduce pain and discomfort.

Adrenaline

A substance secreted primarily by the adrenal glands that helps to prepare the body for exertion. It is involved in regulating blood pressure, heart rate and breathing. Adrenaline can also be used as a drug to treat a number of conditions, including cardiac arrest and anaphylaxis.

General anaesthetic

An anaesthetic given to a person to put them to sleep while having an operation or medical procedure. Afterwards, the person regains consciousness and usually has no memory of the procedure. A general anaesthetic is given in hospital by a specialist called an anaesthetist.

Nebuliser

A device for administering medications via a spray that is inhaled.

Potential complications

Most children recover fully from croup, with no complications. However, in rare cases the following complications can occur:

  • Severe breathing difficulties;
  • Dehydration, or;
  • Secondary infection of the airway (pneumonia), windpipe (tracheitis), epiglottis (epiglottitis), lymph nodes (lymphadenitis), or a middle ear infection.

Seek urgent medical attention if you notice the following:

  • Your child has noisy breathing (stridor) at rest, or;
  • Breathing becomes rapid or causes the chest muscles to become sucked in against the ribs with each breath.

Similarly, see your doctor promptly if your child is agitated, restless, drooling, turning blue, or unusually pale or sleepy.

Epiglottis

A thin flap of cartilage tissue that hangs over the larynx, protecting the airways during swallowing.

Prognosis

The outlook for croup is usually very good when diagnosed and treated early. In most cases, symptoms last for 3-7 days. Sometimes the cough may last for longer, but there is usually no permanent damage. Although the characteristic cough and breathing noises of croup can be frightening, the symptoms often sound worse than they actually are.

Prevention

Croup may be prevented by avoiding contact with people who have a cold. Teaching children good hygiene habits, such as washing hands and covering their mouths when coughing or sneezing, can also help to prevent the spread of viruses. Keeping children with croup away from organised activities is usually recommended until they are feeling well again.

Vaccination against diphtheria and measles can also protect children against infection. Although rare, these infections can lead to particularly dangerous forms of croup.

Vaccination

The practice of administering a vaccine, a solution containing a microorganism (that causes a specific disease) in a dead or weakened state, or parts of it, for the purpose of inducing immunity in a person to that microorganism.