What is asthma?

A definition of asthma

The presence of symptoms (usually more than one of wheeze, breathlessness, chest tightness, cough) and of variable airflow obstruction.

An asthma attack is a sudden worsening of asthma symptoms caused by the tightening of muscles around the airways (bronchospasm). During an asthma attack or if asthma is poorly controlled, the lining of the airways become swollen and inflamed and thicker mucous than usual, is produced.

Lungs showing tightening of muscles around airways

A diagnosis of asthma is primarily a clinical one based on a full history from the patient, the recognition of a characteristic pattern of respiratory symptoms, signs and test results. In the absence of any alternative explanation for these an asthma diagnosis will be a possibility. There is no one test which can give an asthma diagnosis. Tests include a series of peak flow readings and spirometry.