What is the best thing to clear out your lungs if you have shortness of breath/?

Shortness of breath. Shortness of breath may indicate anything from being a bit out of shape, to asthma to heart disease to name a few things. If this is a recurrent problem have it evaluated.
Depends. On why you have shortness of breath. Pneumonia? Antibiotic. Bronchitis? Steroid. Asthma? Steroid and albuterol inhaler. Copd? Antibiotic and steroid. Foriegn body? Removal. Chf? Fluid pill.