Causes of dyspnoea

Reversible causes include:

Lung tumour via chemotherapy
Bronchospasm via use of bronchodilators
Infection via the use of antibiotics
Pleural effusion (accumulation of fluid between parietal and visceral pleura) via drainage of excess fluid
Pulmonary embolism via use of anticoagulants
Heart failure via use of diuretics and antiarrhymics
Anaemia treated by blood transfusions, erythropoietin or iron supplements
Obstruction of the large airways treated by corticosteroids or radiotherapy such as brachytherapy
Pneumothorax

Non reversibole causes:

Malignant conditions such as infiltration into the lungs or progression of neurological diseases affect the control of ventilatory response which contributes to reducing lung function.