Croup | What we need to know

20.01.2026

Croup (laryngotracheobronchitis) is an infectious disease of the respiratory tract, which occurs mainly in young children and infants. The condition is associated with viral infections of the respiratory tract and causes severe swelling and spasm of the pharynx, larynx and bronchi, which causes a barking cough, noisy breathing and a change in voice. Croup is usually characterized by mild manifestations, although in rare cases it can cause life-threatening complications.

Swelling of the airways decreases with age, and croup practically does not develop after the age of 3-5 years. Croup is often caused by the parainfluenza virus, although its development may be associated with the presence of influenza, respiratory syncytial virus, whooping cough, and other infectious diseases.

Croup is very similar to whooping cough in terms of its cough characteristics, however, croup is more a condition associated with viral infections, while whooping cough is a bacterial infection (Bordetella pertussis).

Symptoms of croup

The most characteristic symptom of croup is a harsh, hacking cough. Also pronounced is noisy breathing (stridor), a sharp change in the timbre of the voice.

The course of croup is mild in most cases and lasts no more than a week. In rare cases, symptoms may worsen:

The dough is sticky.
Maral fever
Rash on the skin
Conjunctivitis
Enlargement of lymph nodes

Worsening of croup symptoms may include:

Difficulty breathing
Anxiety and restlessness
Cyanosis (bluish discoloration of the skin)
Retractions – sunken areas of skin in the chest and rib cage area

Causes of croup

The most common causes of croup are viral infections: parainfluenza virus, influenza virus, respiratory syncytial virus, measles, and adenoviruses. Viral croup causes swelling of the upper respiratory tract, which makes it difficult to breathe. However, croup does not necessarily develop in response to a viral infection. Often, a bacterial complication is added to the viral infection, which further aggravates the process of swelling and inflammation of the respiratory tract.

How does croup develop?

Viruses that cause inflammation of the respiratory tract are easily spread in the environment by airborne droplets. When an infected person coughs, sneezes, and talks, they release tiny droplets of saliva that are infected with viruses. In close contact with an infected person, these tiny droplets land on the mucous membranes of the eyes, nose, and mouth of other people, causing inflammation, swelling, and croup of the upper respiratory tract.

What is the duration of croup?

For about 3-4 days after the development of croup symptoms, the child is still contagious, despite the temperature being normalized.

Complications of croup

Most cases of croup are mild and can be treated at home with medical supervision and treatment. Less than 5% of croup cases develop complications that require hospitalization.

If at least one of the following indicators is present, the patient must be hospitalized:

Despite treatment, difficulty breathing progresses, shortness of breath is pronounced
Symptoms of dehydration are evident, requiring intravenous fluid replacement
Inhaled medications do not improve breathing (increasing doses are needed to relieve wheezing)
A decrease in blood oxygen concentration (saturation) is noted and requires oxygen therapy

Diagnosis

The diagnostics of croup is based on the clinical signs and symptoms. A severe hacking cough, wheezing, difficulty breathing, and hoarseness are sufficient to make a diagnostics of croup. Laboratory diagnostics are necessary to identify the pathogen causing the respiratory tract infection. In severe cases, if lower respiratory tract infection is suspected, additional laboratory tests and a chest X-ray are necessary.

The laboratory "Synevo" offers tests for diagnosing viral respiratory infections: