 [ Symptoms ] i had an allergic reaction and was given an oral 30mg dose of prednisone how long will it stay in my system  the allergic reaction was from niacin the prednisone has caused my heart to beat faster how long will this last and will lots of water help flush it faster from my body [ Disease ] since supplement products like these are not regulated by the fda like medications nor tested for safety or efficacy i really do not have any information to determine if they are safe as a pharmacist i generally steer my patients away from supplements like these because they have no proof of safety or efficacy and are usually just a big waste of money