It is possible to perform sputum testing without sputum, that is, to find ways to make the airway produce sputum, and the most common clinical method is the induced sputum test. This is done by nebulized inhalation using hypertonic saline through a nebulizer, which induces an increase in airway glandular secretions, resulting in sputum production. Sputum specimens are then collected and sent to the laboratory for the appropriate sputum testing program, which is commonly used in asthma research. However, special attention should be paid to the contraindications to the induced sputum test. Severe decline in lung function or the presence of hemoptysis, acute asthma attacks, severe pneumothorax, severe heart failure, and active tuberculosis are not suitable for induced sputum testing.