Been on low dose prednisone for 5 years for sarcoidosis in lungs. Doctors can't figure out what causes intermittent lightheadedness (not dizzy). I have passed every heart, brain, ENT, PFT, vascular study, and blood test. O2 is always ok on oximeter. I call it prednipoison cause of rapid heartbeat, don't sleep well, and other minor effects. Had afib twice 4 years ago but none since. Doctors don't think prednisone can cause any illness. I can't find a prednisone expert either.