Chael Sonnen announces he’s retiring from MMA after 17 years of fighting

Chael Sonnen’s recent failed drug test hasn’t just led to him being pulled from UFC 175. It also will mark the end of his MMA career.

Sonnen announced his retirement from competition Wednesday on "UFC Tonight," one day after news came out that he had tested positive for banned substances and likely would not be able to fight Vitor Belfort on July 6 in Las Vegas. Sonnen has competed in MMA for 17 years, including the past five with the UFC.

At the top of the show, Sonnen further explained why he was taking human chorionic gonadotropin, anastrozole and clomiphene. The latter two are anti-estrogen medications typically given to women. Sonnen, 37, said he has hypogonadism, an affliction that affects the output of testosterone. He was on testosterone replacement therapy (TRT) before it was banned by the Nevada Athletic Commission in February. Once he came off that, Sonnen said, doctors prescribed him anastrozole and clomiphene with the hope of stimulating natural testosterone production.

In some ways, it worked. Sonnen said he had fertility issues previously and now his wife Brittany is pregnant with their first child. He said he was putting his health and family first and would do the same thing again if given the choice.

Sonnen took responsibility for his actions and said he should have disclosed to the NSAC that he was on the drugs. He said Tuesday on "America’s Pregame" that he was "confused" about commission regulations for out-of-competition testing, since the tests came last month and the fight was in July. Also, he took exception to the claim that the two drugs found in his system were performance-enhancing — Sonnen said they are for his health and would not help him in the Octagon.

Furthermore, he said, they are legal in the United States unlike anabolic steroids. However, anastrozole and clomiphene are banned by the World Anti-Doping Agency (WADA).

Sonnen (28-14-1), one of the biggest pay-per-view draws in the UFC, is perhaps best known for his heated rivalry with former middleweight champion Anderson Silva, whom he thanked profusely Wednesday on "UFC Tonight." The feud was one of the most memorable in MMA and Sonnen nearly won the title from Silva in August 2010, dominating four rounds against the all-time great before being submitted at 3:10 of the fifth by a triangle choke.

After that fight, Sonnen tested positive for elevated testosterone levels. He was suspended by the California State Athletic Commission, but worked his way back to beat Brian Stann and Michael Bisping, earning another shot at Silva.

That rematch, in July 2012, was one of the biggest-drawing UFC bouts in recent years. Silva beat Sonnen again, this time by TKO in the second round.

Sonnen’s days as a title contender were not over. His very next fight was a matchup with light heavyweight champion Jon Jones, which Jones dominated and ended at 4:33 of the first round by TKO. After that, Sonnen beat Mauricio "Shogun" Rua on the FOX Sports 1 launch card in August and fell to Rashad Evans in November.

Sonnen is best known for his trash talk, which has made him one of the most popular — and divisive — fighters in UFC history. His rivalry with Silva was fueled by Sonnen tearing the then-champion down, making fun of everything from his appearance to his home country of Brazil. Sonnen did the same to Jones en route to earning that title shot and a spot as coach on "The Ultimate Fighter."

Sonnen was supposed to settle another score with a major rival in Wanderlei Silva next month after the two got into a fight on the set of "The Ultimate Fighter: Brazil," but Silva allegedly evaded a random drug test from the NAC and Belfort, another fighter Sonnen has traded barbs with, stepped in. It’s unclear if Belfort, who has his own past drug issues, will remain on the UFC 175 card.

Sonnen and his wife Brittany are expecting their first child.

Before Sonnen started speaking up, he was a journeyman 185-pounder with stints in WEC, Pancrase and Bodog Fight. At his best, though, the former Division I wrestling All-American and Olympic trialist was a guy who could beat any middleweight in the world outside of Silva. Sonnen also is known for being a company man who would step in at a moment’s notice to take a fight if someone else had pulled out with an injury.

His charisma has made Sonnen a rising star on FOX Sports 1, hosting "UFC Tonight" with Kenny Florian and also acting as an analyst for UFC live events.

That’s the role everyone will be seeing him in from now on, because Sonnen said his fighting career has come to an end.