For girls with childbearing potential, a negative pregnancy test before taking and while taking study medication. Sexually active females must be using an effective form of birth control. These methods include total abstinence (no sex), oral contraceptives ("the pill"), an intrauterine device (IUD), levonogestrol implants (Norplant), or medroxyprogesterone acetate injections (Depo-provera shots). If one of these cannot be used, contraceptive foam with a condom is recommended.