Theophylline, ephedrine, guaifenesin and phenobarbital - fee-noe-BAR-bi-tal combination is using to treat the symptoms of bronchial asthma, chronic bronchitis, emphysema and other lung diseases. This drug relieves cough, wheezing, shortness of breath and troubled breathing. It works by opening up the bronchial tubes - air passages of the lungs and increasing the flow of air through them.