Tbol is 17-alpha-alkylated (17aa) to survive the first pass through the liver. You need to be very careful when stacking it with other oral steroids at moderate to high dosages due to potential kidney, liver issues. This means you must use a liver/kidney support supplement with it, such as N2Guard . I suggest sticking to a maximum two (2) orals per 6 weeks regiment and never stacking more than two (2) oral-steroids at a time. Although tbol generally has less side effects than other AAS, it should still be respected, as it is a powerful hormone.