no- slimfast is safe- that is definately NOT a common side effect becasue there are none and if there were slim fast would by law have to tell their customers that. well- in vermont slimfast is 6 dollars around for 6 shakes or 6 bars so it's like a dollar a meal which is a lot cheaper then if you were going to buy it from school or a resteraunt or anything like that. good luck on whatever you decide...