Commissioner Bud Selig is considering his options. While Rodriguez can't be disciplined for testing positive, it's possible baseball could try to punish him for acknowledging steroid use from 2001 to 2003.
Selig told USA Today on Wednesday afternoon that he is "just heartsick" about Rodriguez's admission and would not rule out punishing him or adjusting baseball's record book.
Selig told USA Today he "had put a bulletin out" about the illegality of steroid use in 1997, even though MLB had no drug testing at that time.
"It was against the law, so I would have to think about that," Selig told USA Today when asked about possible action against Rodriguez. "It's very hard. I've got to think about all that kind of stuff."
Donald Fehr, executive director of the Major League Baseball Players Association, said Wednesday he didn't anticipate disciplinary action against Rodriguez.
"I would be surprised if there was an attempt to do it," Fehr told USA Today. "I don't know anything about that."
Still, any penalty is highly unlikely.
Rodriguez was evasive during an ESPN interview when asked for details of his drug use, though he did say he has been clean since joining the New York Yankees in 2004.
"I don't know exactly what substance I was guilty of using," he said.
He'll face more questions when he reports to spring training with the Yankees next week. Manager Joe Girardi will hold his first staff meeting of camp Thursday, and position players are to report by Tuesday. Full-squad workouts start the following day.
Meantime, the chairman of the committee that determines the banned-substances list for the World Anti-Doping Agency says he still has plenty of questions for Rodriguez.
"In doping, the devil is in the details, and I think he needs to come forward with the details," Gary Wadler said.
Rodriguez's confession was in response to a Sports Illustrated report that he tested positive for Primobolan and testosterone during baseball's anonymous survey in 2003.
Among the questions Wadler would like to ask:
• Did Rodriguez take steroids orally, by injection or both?
• How did he obtain the substances he used?
• Did he inject himself? Did someone else inject him?
• Was he taking dietary supplements?
• Did he share vials?
• Did he use in-season, offseason or both?
• How frequently did he use each substance?
• Did he use multiple substances at the same time?
"Those questions have to be asked and answered, and not only answered, but it has to answered in a convincing manner, not through a handler or a wordsmither," Wadler said.
The Associated Press contributed to this report.