Lesnar failed both tests for the same banned substance and according to LA Times writer Lance Pugmire, Lesnar tested positive for estrogen Clomiphene. This is the same substance Jon Jones previously tested positive for and is among bodybuilders looking to increase while cycling off of steroids.
Pugmire the following:
before and after the fight. Lesnar previously failed an out-of-competition drug test from a June 28th sample taken by the US Anti-Doping Agency.
I'm told by an official with knowledge of Brock Lesnar's positive test that the substance is clomiphene, the same one found in @JonnyBones.— Lance Pugmire (@latimespugmire) July 19, 2016