This 37-page handbooks is something that all athletes, guardians, coaches and medical professionals need to be aware of in terms of the anti-doping efforts and clean sports. Worthy of a read and download.
2018 edition
2018-usada-athlete-handbookThis resource page is part of the ebook
The process for obtaining a therapeutic use exemption or TUE is explained here: https://www.usada.org/substances/tue/