It might depend on the brand, the formulation and the dosage. Remember, there are people out there who think that "if a little is good, then a lot must be better!" These are the ones who may be suffering bad effects. As always, Use Discernment At All Times. When in doubt, you can do muscle testing. Hold something in your dominant hand; ask yourself, "Is this ok for me?" and if you start to lean forward, it is ok, if you start to lean back, be very cautious. Everyone has a unique system. Shall post more on muscle testing.