You have to maintain the consisitency of the characters you use，I mean you need to use either the traditional charatcers or the simplified ones, a mix of both in one writing is highly unrecommended.

苦口良药

我劝她吃药。虽然药很苦，但是可以帮她治病。俗話说:苦口良药。不过，她很固执的说打死她都不吃。现在呢，你看,她还是臥病在床 。