Is all drugs approved by FDA safe?

PL

OK Nobody seems to be answering my question. I'll try to raise the question in a different way. What is the factor that usually makes one drug approved while the other is disapproved by FDA? When a drug is approved by FDA, does it imply that it is legally possible, but very unlikely in terms of probability to cause a side effect that will outweigh the benefits or a side effect that does not worth the benefits it gives?