"Yes, it is a side effect of the drug, but it is just constrained to the shift. Theoretically Rain should regain her sensed once her senses is used to the sudden smell of blood. Let me make an analogy, when you enter a place with a certain smell your senses perceived it fully and you are able to tell differentiate the smell. But if you stay in that place for a while longer the smell slowly fades away as you get used to it. Although the smell is still there and any new person there will smell it just as powerfully as when you entered the room, but you would not feel it. This time is the time that Rain should remain shifted but that is not the case."