Do new medicines safer than old ones?

Source: Kingworld medicine

Generally speaking, a new medicine has to prove the safety and effectiveness before it is permitted to be in use. However, the advantages of new medicines may not be more effective and less adverse reaction. Sometimes the effectiveness and adverse reaction rate of new medicines is almost the same with old ones, but it is permitted to be a new medicine with the reasons of easily found raw materials, convenient production technique, or low price etc.