My husband started taking this to improve his sperm quality. After a week, he began getting numbness & tingling in his hands. We asked our doctor who said that Fertailaid for Men has been known to cause that due to the high levels of one of the B vitamins, and recommended he stop taking it right away since the numbness can get progressively worse, and in some cases is permanent.I don't think they should even be allowed to sell this stuff.