People with pre-existing airway hyperreactivity, such as asthmatics, will react to lower doses of drug.
Sometimes, to assess the reversibility of a particular condition, a bronchodilator is administered to counteract the effects of the bronchoconstrictor before repeating the spirometry tests.
In addition, asthma may be temporary due to an exposure to noxious stimuli or exercise.
The bronchial challenge test is physically demanding, and the results can be affected by muscular weakness or exhaustion.
Also contraindicated by the presence of an aortic aneurysm, as spirometry will increase blood pressure, in proportion to both the patient's effort and the degree of obstruction in the lungs.