I wouldnt run it past 8 weeks but as far as toxic like Anadrol or something on that lines, not even close. Acoording to my doctor, you could do more damage to your liver in 6 weeks drinking a six pack a day. He also said being a doctor he wouldny recommend either one. Anavar is very mild.
Google it and look at some of the things it is used for in treatment. Give you a hint, seroius long time alcoholics to get strength back. How toxic is it?