I was on cellcept for about a month, no leg cramping issues, but I was still taking my infusions (think IVIG at the time) and my infusion nurse was noticing my resting heart rate was 138, pretty high for sitting in a chair doing nothing. We isolated my drugs at the time and when I went off cellcept my resting heart rate dropped back down to 80's in a few days. It seems this is a rare side effect, but no cellcept for me. currently i'm on prednisone and vyvgart, the vyvgart has had much better effects for me than the ivig, both are infusion therapies. When I was on ivig i had trouble picking up a 3 gallon gas can and putting it in the car. on Vyvgart, i can do that, no problem. But different people react to different therapies differently.