I take it for sinus arrhythmia (heart) Doctor thought I was getting a rash from my Theophylline (have taken over 30 years) stopped taking it for 4 months , rash still there and spreading. I also take Armor Thyroid. I stopped that for a couple of weeks. Had biopsy done, not fungal, bacterial or malignant. Rash is on thighs (where it started) now on stomach, breasts, & upper arms.