Romero was flagged by the U.S. Anti-Doping Agency for a potential violation of the UFC's anti-doping policy for an out-of-competition test. The news of the violation was made public about a month after Romero defeated Ronaldo Souza at UFC 194.
The 38-year old Blackzilians fighter is still awaiting the results of his B-sample test, MMAFighting.com's Ariel Helwani reported on Wednesday's edition of UFC Tonight.
According to Romero's agent, Malki Kawa, the fighter disputes the results of the test, saying he passed all tests administered before the one which came up positive and all tests conducted since.