I had bad social phobia, very bad, where I would make it a point to miss social events. The thing that made me change my life around was being sick of always being alone and wanting to be in a relationship with a woman. Being alone and not expressing myself to other people got old after a while and I decided I had to put myself out there even if it meant looking stupid or taking a hit to my ego. When I first started talking to strangers and girls I was terrified and thought I could never do it, but the more I did it, the easier it became, to the point today where it is pretty easy to be social with other people. For just taking the "risk" of putting myself out there and being uncomfortable and self conscious I now have an awesome girlfriend and a relationship I didn't think I could ever have.
I think the point is that if you are naturally introverted there is no "cure" because that is just who we are, just like extroverted people can't be cured of their natural tendances. Just embrace who you are, talk to a stranger, try to flirt with a girl ask her for her number, if she turns you down move onto the next one, do it every day, do it on weekends just make a point to do it. After you do it for a while you won't have any social anxieties when approaching friends and strange women. Getting a girlfriend also helps with social phobia because it builds confidence plus you get a whole new set of friends.
I dunno that's how i overcame my social phobia without drugs.