At a hearing held today in Las Vegas, the Nevada State Athletic Commission confirmed that Jon Jones’ positive drug test failure last month was for two estrogen blockers. Both hydroxy-clomiphene and letrozole metabolites were found in Jones’ system following his June 16 USADA test in the lead-up to UFC 200. After the test failure was announced, Jones was pulled from the UFC 200 card and eventually replaced by Anderson Silva, who met Jones’ original opponent Daniel Cormier in a non-title bout. For his part, Jones would profess his innocence in an emotional press conference, but the damage was done.

Both Rashad Evans and Chael Sonnen previously stated that they had been informed that it was in fact estrogen blockers that Jones tested positive for.

At today’s hearing. Jones’ temporary suspension was extended to allow for a hearing expected to be held in September or October. Jones is expected to contest the finding, though with his B-sample having tested positive as well, his avenues of defense may be limited. Tainted supplements seem to be the current go-to, but time will tell.

For those wondering what benefit an estrogen blocker would be to a professional athlete, the reality is that they are usually paired with other agents to counter-balance the aromatization process, in which estrogen in the body increases when testosterone is increased (potentially via an anabolic agent). Of course, that has not been proven in the case of Jones, but it is the most common reason for an athlete to be on estrogen blockers.

The news comes as rumors swirl that the substance Brock Lesnar apparently tested positive for in an out-of-competition test prior to UFC 200 was asthma medication. There has yet to be any confirmation by the USADA, UFC, or athletic commission on that case. For now, the Jones situation is front and center — though it seems there won’t be any real answers until the fall.

About The Author

Senior Staff Writer

Covering the sport of MMA from Ontario, Canada, Jay Anderson has been writing for various publications covering sports, technology, and pop culture since 2001. Jay holds an Honours Bachelor of Arts degree in English from the University of Guelph, and a Certificate in Leadership Skills from Humber College under the Ontario Management Development Program. When not slaving at the keyboard, he can be found in the company of his dog, a good book, or getting lost in the woods.