"i&#039;ve been using it for 4 years. never had a problem. i never had side effects until i got off it for a couple months and then went back on. i got some nausea and vomiting, but i&#039;ve always had a sensitive stomach so it had to do with a combination of things. all in all, it&#039;s the best. i switch from butt cheek to butt cheek each week. it&#039;s less likely to fall off if your sitting on it."