Croup is a childhood condition that affects the windpipe (trachea) and the two airways that branch off from it to the lungs (the bronchi).

A child with croup has a distinctive barking cough and they will make a harsh sound, known as stridor, when they breathe in. A blocked airway can also cause a hoarse voice and breathing difficulties.

Types of croup

There are two types of croup:

  • viral croup (laryngotracheitis), which develops over several days and is caused by an infection
  • spasmodic croup, which involves repeated, short-lasting episodes of croup where no infection is present

The same treatments are recommended for both viral croup and spasmodic croup.

How common is croup?

Croup is a fairly uncommon condition that tends to affect more boys than girls.

Croup usually affects young children aged between six months and three years, with most cases occurring in two-year-olds. However, croup can sometimes develop in older children up to 15 years of age.

It is occasionally possible for a child to experience croup more than once during childhood, with one study finding that it recurs in around 5% of cases.


Most cases of croup are mild and get better on their own, without the need for treatment.

Around 60% of croup cases clear up within 48 hours. However, in some cases, the symptoms of croup can last for up to a week.

Urgent hospital admission is needed in more severe cases of croup where the airway is blocked and the child has life-threatening breathing difficulties.

It is very rare for a child to die from croup.

The larynx is the part of the throat that contains the vocal cords. It is used for breathing, swallowing and talking.

A child can get croup at any time of the year, although the condition is more likely to occur during the late autumn and early winter months. This may be because there are more colds and viruses around at this time of year.

The initial symptoms of viral croup are similar to those of a cold. They include:

  • sore throat
  • runny nose
  • high temperature of 38°C (100.4°F) or above (in some, but not all, cases)
  • cough

Over one to two days, the more specific symptoms that are characteristic of croup will develop. These symptoms are:

  • a bark-like cough
  • a hoarse or croaky voice
  • difficulty breathing
  • rasping (a harsh grating sound) when breathing in, called stridor

The symptoms of spasmodic croup are similar to those mentioned above. However, a bark-like cough and stridor tend to occur suddenly (usually at night), with the child feeling well before the specific croup symptoms begin.

Stridor is often most noticeable when the child cries or coughs. However, in more severe cases of croup it can also occur when the child is resting or sleeping. For reasons that are unclear, the symptoms of croup tend to be worse at night.

Although the symptoms of croup usually only last for a few days, they can occasionally last for up to a week.

When to seek medical advice

Croup is a condition that can usually be diagnosed by a GP and mild cases can usually be effectively treated at home.

However, if your child's symptoms are severe (see below), you should take them to the nearest hospital's Emergency Department or dial 112 (999)for an ambulance.

You should seek immediate medical attention if your child has any of the following symptoms:

  • severe breathing difficulties
  • increased breathing rate (they are too breathless to feed or talk) or 'silent chest' (you are unable to hear sounds of breathing)
  • worsening cough or rasping sound (stridor)
  • distress and agitation
  • drooling of saliva
  • the skin appearing dark, blue-tinged or pale
  • the skin around the ribs and chest appearing to be pulled in and tight, making the bones of the chest and ribs more visible
  • abnormal drowsiness and sleepiness
  • a high temperature of 38°C (100.4°F) or above
  • a rapid heartbeat

Some of these symptoms may indicate a potentially life-threatening underlying condition called epiglottitis (inflammation of the epiglottis, which is the flap of cartilage that closes off the entry to the voice box when you swallow). The symptoms could also indicate tracheitis (inflammation of the windpipe), which also requires immediate medical attention.

Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Croup usually develops as a result of an infection, often by a virus and sometimes by bacteria. The infection causes the larynx (voice box) to become swollen and the trachea (windpipe) to become blocked.

Parainfluenza virus

The parainfluenza virus is the most common virus that causes croup. Three different strains of the virus are responsible for around 80% of croup cases. These are:

  • parainfluenza I
  • parainfluenza II
  • parainfluenza III

Parainfluenza I is the strain responsible for most cases of croup.

The virus can be transmitted through close contact with people who are infected and through infected objects and surfaces. As with many airborne viruses, the parainfluenza virus is often spread when someone who is infected coughs or sneezes and the infected droplets are breathed in.

It is important for children and adults to:

  • always cough and sneeze into a tissue, before throwing it away immediately, and to
  • wash your hands immediatley after that.

Most of the time, unless specific swabs are taken from the patient, we do not know which virus type causes croup

Other viruses

A number of other viruses can also cause croup. These include:

  • influenza A and B (flu viruses)
  • the measles virus, in children who have not been immunised against measles
  • the herpes simplex virus (cold sore virus)
  • the varicella-zoster virus (chickenpox virus)
  • the adenovirus
  • the rhinovirus
  • the respiratory syncytial virus (RSV), which can cause severe breathing problems and pneumonia in babies
  • Mycoplasma pneumoniae, which is a bacterium that can sometimes cause pneumonia

Less common causes

Other, less common causes of croup include:

  • an allergic reaction to substances such as pollen or dust mites
  • inhalation of irritants, such as chemicals
  • acid leaking back out of the stomach and into the throat (acid reflux)

Most of the time, because croup is a mild self-limiting problem, we do not check which virus is causing it.

Your GP will diagnose croup based on your child's symptoms and, in particular, the sound of their cough. The doctor may also take your child's temperature to check for a fever and will ask you whether your child has recently had a cold or a viral infection.

Based on their assessment, your GP will decide whether hospital admission is required or whether your child's croup is safe to treat at home or at the GP surgery.

Ruling out other conditions

Your GP will want to rule out any other conditions that may cause similar symptoms to croup, such as epiglottitis (inflammation of the epiglottis) and tracheitis (inflammation of the windpipe).

Other possible causes for your child's symptoms are:

  • an abnormality of the airway, which has been present from birth
  • an abscess in the tissues in the back of the throat
  • inhaled material
  • swelling of the deeper layers of the skin (angio-oedema)

Further investigation

If your child is admitted to hospital with severe croup, or if treatment proves to be unsuccessful, further investigations may be needed to examine their neck and chest area for a possible obstruction. This would be a rare cause of croup.

An X-ray may be recommended if it is thought that inhaled material is obstructing your child's airway.

You should not try to check your child's throat yourself, because it could trigger a spasm (sudden narrowing) of the airway. This could cause the airway to swell even more, making breathing even more difficult.

The treatment of croup depends on how severe the condition is. Most cases of croup do not need treating because the condition usually gets better on its own and often only lasts for a short period of time.

However, if your child has severe croup, they will need to be admitted to hospital urgently.

Comforting your child

If your child is distressed, sitting them upright on your lap will help to comfort and reassure them. Comforting your child is important because if they are crying and distressed, it may make their symptoms worse.

Treating mild croup

Mild cases of croup can be managed at home. If your child has a fever, paracetamol will help to lower their temperature. Your child should also drink plenty of fluids to ensure that they remain well hydrated.

Although there is a lack of scientific evidence to support its use, it may be of benefit to supervise your child while they breathe in steam from a hot bath or shower in a closed room.

You should seek urgent medical advice if you notice your child's symptoms getting worse.


Painkillers, such as paracetamol and ibuprofen, are available in liquid form, which makes them ideal for young children. You can get liquid paracetamol over the counter from pharmacies and some supermarkets.

You should not give paracetamol to your child if they have previously had a bad reaction to it or if they are sensitive to it. Children under 16 years of age should not be given aspirin.

Babies and children aged over three months can be given ibuprofen as long as they weigh over 5kg (11lb) and they do not have a history of asthma, heart problems, kidney problems, stomach ulcers or indigestion. As with paracetamol, you should also avoid giving children ibuprofen if they have a history of bad reactions or sensitivity to it.

Before giving any medication to your child, make sure you read and follow the dosage information on the packaging or patient information leaflet that comes with the product.

Speak to your GP or pharmacist if you are unsure about what type of painkiller is suitable for your child.

Moderate croup

If your child has moderate croup, your GP may decide to prescribe corticosteroids to help ease their symptoms. Corticosteroids reduce inflammation (swelling) in the throat.

Dexamethasone or prednisolone are two types of corticosteroid that are often used to treat moderate croup.

This type of medication can be taken as a tablet or inhaled using a nebuliser (an inhaler device).

Although they are frequently used potential side effects of these corticosteroids include:

  • restlessness
  • vomiting
  • anxiety
  • upset stomach
  • headache
  • difficulty falling asleep or staying asleep

Major side effects with steroids are unusual in the short courses of treatment that are normally used for croup.

Severe croup

Breathing problems, such as shortness of breath, are a major symptom of severe croup.

You should dial 112 (999) immediately for an ambulance if your child is struggling to breathe.

If your child is very distressed and they are finding it very difficult to breathe, they will be given oxygen through an oxygen mask.

An oral corticosteroid will also be given to help reduce any inflammation (swelling) in your child's airways. Soluable prednisolone is usually prescribed for cases of severe croup.

However, if your child is unable to tolerate the side effects of this treatment, they may be given another type of corticosteroid called budesonide. If necessary, a nebuliser can be used to administer the medication.


In less than 1% of croup cases that require hospitalisation, a child may need intubation. This would be quite rare. Intubation is where a tube is inserted either through a nostril or the mouth and passed down into the windpipe. This will help your child to breathe more easily.

Intubation is usually performed under general anaesthetic. This means your child will be completely unconscious throughout the procedure so they do not experience any pain or distress. 

A high temperature, also known as a fever, is when someone's body temperature goes above the normal 37°C (98.6°F).

Complications that develop as a result of croup are rare, with less than 5% of children with croup needing to be hospitalised.

Airway obstruction

If an obstructed airway is not treated promptly, it can lead to:

  • severe breathing difficulty (respiratory distress)
  • respiratory arrest (where breathing stops but the heart continues beating)

Always call 112 (999) for an ambulance if your child is struggling to breathe.

Your child may find it difficult to drink fluids as a result of an obstruction in their airway. However, it is important that they have plenty of fluids to avoid dehydration.

Secondary infection

A secondary infection can sometimes develop following the initial viral infection that caused croup. A secondary infection can potentially cause:

  • pneumonia, which is swelling of the tissue in one or both lungs, usually caused by an infection
  • bacterial tracheitis, which is a serious and potentially life-threatening infection that can occur after a viral respiratory infection

Other possible complications

Other possible complications of croup can include:

  • otitis media, which is a build-up of fluid in the middle ear
  • pulmonary oedema, which is a build-up of fluid in the lungs, which causes shortness of breath
  • pneumothorax, which is a collapsed lung that results from air leaking into the space between the lungs and the chest wall
  • lymphadenitis, which is an infection of the lymph nodes (the glands that make up part of your immune system)

Most cases of croup are mild and resolve without the complications listed above.

The infection that causes croup is often spread through infected droplets of moisture that are passed through the air when someone coughs or sneezes. It can, therefore, be difficult to prevent spread of the infection.

Preventing infection

To try to limit the spread of infection, you should always practise good personal hygiene and teach your children to follow this from an early age. For example, both you and your child should:

  • wash your hands regularly
  • always cough and sneeze into a tissue, before throwing it away immediately
  • clean surfaces regularly to keep them free of germs
  • avoid sharing unwashed cups, plates, cutlery and other kitchen utensils

Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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