Nye County Sheriff Sharon Wehrly says an employee for Love Ranch told 911 dispatchers that Odom was found unresponsive with blood and "white stuff" coming from his nose and mouth.
The caller said Odom, 35, had used cocaine before his arrival Saturday but wasn't sure whether his use had continued through the weekend. The caller also said Odom had taken up to 10 tabs of an over-the-counter sexual-performance enhancer over the previous three days.
Odom is on life support at a Las Vegas hospital, and sources told ESPN there was some small improvement Wednesday. However, one cautioned that he is "not out of the woods yet."
Sources had said earlier Wednesday that "the next 48 hours are critical."
With a search warrant, Nevada authorities took a blood sample from Odom early Wednesday to determine exactly what was in his system, but the results could take several weeks.
Nye County Sheriff's Detective Michael Eisenloffel said at a news conference Wednesday that Las Vegas police will be doing the testing.
Eisenloffel described the enhancers as supplements and said Odom bought them at the brothel.
In a recording of a 911 call, brothel spokesman Richard Hunter said Odom was breathing but in a "deep sleep" when he was found, and had fluid coming from his nose and mouth.
"He sounds like he's snoring a little bit. But he is breathing consistently," Hunter said.
Hunter said Odom reported doing cocaine before his visit and knew the brothel had a strict anti-drug policy. The women who work there are trained to "stop the party" if drugs are seen, Hunter added.
Dennis Hof, who owns Love Ranch and other legal brothels in Nevada, said his staff picked up Odom from a home in Las Vegas on Saturday.
"He just wanted to get away, have a good time and relax," Hof told The Associated Press in a phone interview.
According to Hunter, Odom stayed at the "best VIP suite" on an open-ended reservation and was accompanied by two women. He spent an amount beyond five figures, which would have been negotiated privately between him and the prostitutes. The women are contractors who get 50 percent of the negotiated price.
Hof said Odom was "happy, he was sleeping every night" while visiting, but two women went to check on Odom on Tuesday afternoon, after not hearing from him since early morning, and they found him face down and unconscious. When they turned him on his side at the direction of a 911 operator, Odom started "throwing up all kinds of stuff."
Hof said Odom had been taking herbal sexual-performance enhancers and had consumed part of a bottle of cognac since arriving, but Hof had no knowledge of Odom's use of any other drugs.
Odom, who won two NBA championships with theLakersin 2009 and 2010, last played in the NBA in 2013. He saw recent reality TV fame through his four-yearmarriage to Khloe Kardashian.
Kardashian, who filed for divorce in 2013 citing irreconcilable differences, has been by Odom's side at the hospital since Tuesday evening, a source close to the Kardashians told the AP.
Lakers star Kobe Bryant, who was in Las Vegas for an exhibition game Tuesday, visited the hospital, sources told ESPN's Ramona Shelburne. The Los Angeles Daily News reported that Lakers general manager Mitch Kupchak visited the hospital as well.
ESPN.com's Ramona Shelburne and Marc Stein and The Associated Press contributed to this report.
Lamar Odom showing small signs of improvement
Ramona Shelburne reports the latest on Lamar Odom's condition.
Odom found with blood, white substance coming from nose
Nye County Sheriff Sharon Wehrly says a 911 caller reported that Lamar Odom had been doing cocaine and using sexual-performance enhancers before his collapse.
Odom unresponsive, hospitalized
ABC News correspondent Kayna Whitworth reacts to the news that former NBA star Lamar Odom was hospitalized Tuesday after he was found unconscious at a Nevada brothel.