Silva, 40, made his return to the octagon on Jan. 31 more than a year after his last fight against current middleweight champion Chris Weidman, in which he broke his leg. His win has also been overturned and he's been fined $380,000.
"The UFC organization maintains a strict, consistent policy against the use of any illegal and/or performance enhancing drugs, stimulants or masking agents by its athletes, and fully supports the Commission's ongoing efforts to ensure clean competition by all MMA athletes," the organization said in a statement.
The Brazilian former longtime champion failed tests before and after the fight. The positive tests, Silva's camp said, were the result of him taking a supplement to improve sexual performance.
"I am human and made mistakes," Silva told the Nevada Athletic Commission, according to ESPN. "It definitely was a mistake. If I had known this supplement that I was taking for something else would have caused this sort of problem, I never would have taken it."
Silva (33-6) will be eligible for reinstatement on Jan. 31, 2016, contingent on his ability to submit a clean drug test.