Brock Lesnar won’t be back in the Octagon for a while.

Lesnar, the UFC heavyweight champion from 2008 to 2010, has been suspended for a year after testing positive for banned substances before his fight against Mark Hunt at UFC 200 on July 9, 2016, the United States Anti-Doping Agency (USADA) announced Wednesday.

The 39-year-old defeated Hunt in a unanimous decision. But results from an out-of-competition urine test in June and an in-competition urine test on July 9 turned up positive for clomiphene as well as its metabolite, 4-hydroxyclomiphene. Clomiphene—sometimes also spelled clomifene—is an anti-estrogen agent, and it's prohibited at all times under the UFC Anti-Doping Policy, which follows the WADA Prohibited List. The agent can “indirectly raise natural testosterone levels in the body, and can also counter the side-effects of anabolic steroid use,” according to Reuters.

To be clear: The USADA did not say that Lesnar tested positive for steroids. But steroid users sometimes turn anti-estrogenic drugs like clomiphene to reduce the rise in estrogen levels that accompanies the rise in testosterone levels. “With [anabolic steroid use], it’s pretty common to get either enlargement of the breasts (gynocomastia) or tenderness of the tissue (mastodynia)," Dr. Stuart Weinerman, M.D., an endocrinologist at North Shore–LIJ Health System in New York, told Men's Fitness in 2016. "Most of the androgenic drugs that people use result in this."

And while clomiphene is normally used to treat infertility in women, the WADA bans it in athletes because it can also help restart natural testosterone production. Lesnar’s representatives originally said back in October that the fighter had used asthma medication, eye medication, and foot cream that could have been the cause of the positive tests.

Lesnar’s ban will end on July 15, 2017, although it will not keep from appearing in WWE events. The ban is partially retroactive; it began on July 15, 2016, when the USADA provisionally suspended him from competition. The Nevada State Athletic Commission also overturned Lesnar’s victory at UFC 200 to a no-contest.