The 40-year-old Tapia was in serious condition at Presbyterian Hospital, said Todd Sandman, the hospital's director of public relations.
Meanwhile, Tapia's family was mourning the loss of the boxer's brother-in-law.
State police said Robert Gutierrez, 39, was killed along with his 23-year-old nephew, Ben Garcia, early Tuesday when his vehicle went off a highway in northwestern New Mexico and rolled, ejecting both men. Family members said the two were returning to Albuquerque to see the ailing boxer.
Teresa Tapia, the boxer's wife and manager and Gutierrez's sister, said her husband was not aware of the accident and she was concerned about how he would react once he found out, the AP reports.
"He's done a lot better. He's made a lot of progress. This may not have killed him, but this news," she said, referring to the deaths of her brother and Garcia, "... this is just going to devastate him."
Tapia was taken to the hospital on Monday after paramedics responded to an early morning call about a person who wasn't breathing at a hotel room, said officer Trish Hoffman of the Albuquerque Police Department.
"It appears to be an overdose," Hoffman said. "He will be charged with possession of a controlled substance."
Police discovered a plastic bag containing a white substance, which Hoffman said was confirmed by tests as cocaine.
Tapia's latest episode with drugs comes more than two weeks after he won a majority decision over Evaristo Primero in a fight billed as Tapia's farewell performance from the ring. He has a 56-5-2 record.
Tapia was banned from boxing for 3Ѕ years in the early 1990s because of his cocaine addiction. He spent six months in rehabilitation in 2003 after a collapse at home and later that year police said he overdosed on prescription pills.
It's has been a hard life outside the ring for Tapia, who was orphaned at 8, his mother stabbed 26 times with a screwdriver. He never knew his father and has battled cocaine addiction, alcohol, depression and numerous run-ins with the law.
In his book "Mi Vida Loca," Tapia said he's been declared clinically dead six times.
Inside the ring, Tapia won five titles in three weight classes, and celebrated victories with a backflip. Tapia won the WBA bantamweight title, the IBF and WBO junior bantamweight titles and the IBF featherweight belt.