This Tara thing may not even be about herself taking the drugs....I mean consuming the actual drug. Perhaps it's something else, like what they did with Eric/Marisol.
Either way, I don't think Ryan knowing about it will do him any harm. It's not as if he knows she stole them & let Julia take the blame - apparently he just thinks she's using, right? He might just be a little concerned, offers some advice & let's it go from there - I don't think this spoiler necessarily means that her drug habit (or whatever it may be) will be a permanent link to Ryan's character. Again, either way, I actually like the idea of him getting a little involved. Since Alexx has left, Ryan doesn't really have that "pal" anymore - he's sorta the guy who get's pulled in every direction, so this could be really good for him in showing some empathy & letting the audience get a feel for what he went through in his own addiction (gambling).
On another note - I am not thrilled that a newbie is already getting a story, no less one that's about addiction/drugs...but oh well, whatever tickles their freakin' pickle, I guess.