Later at a news conference promoting the Sun Bowl, where USC was defeated earlier this week, Kiffin said he had no idea when or if Toradol was being used on his players, or about its risks.
"Well, if that was the case then, yeah, I did not know that until you told me," Kiffin said. "You educated me, thank you."
USC and Dr. Tibone have asked a judge to throw out Armstead's lawsuit, and in a brief interview with ABC News, Dr. Tibone denied any wrongdoing.
He said he could not comment on whether he failed to tell Armstead of the possible risks of the prescription painkiller, because of the pending lawsuit.
The team doctor did confirm to ABC News that he used Toradol to treat Armstead's pain and that he continues to use the drug on other USC players.
"These are young, healthy people," he said. "We still use it, we use it diligently."
Whatever the possible risks, an expert on medical ethics, Professor Arthur Caplan of New York University, said team doctors have an obligation to tell players.
"Even if you're the team physician, you still have to follow the standard of care and informed consent," Caplan told ABC News. "You better be disclosing all risks."
In addition to Oklahoma and Nebraska, only four of the other top college football programs questioned by ABC News said Toradol is not used by their team doctors: Ohio State, Oregon State, Boise State and Georgia.
Most schools refused to answer whether players are treated with Toradol, but four confirmed its doctors use the painkiller: Clemson, Texas A&M, San Jose State and USC.
In professional sports, the NFL, NHL and NBA allow the use of Toradol but require teams to keep close track of injections and report the information to the league.
The NCAA, the governing body of college sports, has no such requirement to regulate or even track the use of painkillers, a spokesperson told ABC News.
In a statement, the NCAA said it requires member schools to follow state and federal laws about medical treatment and prescription medicine, and publishes guidelines that include "best practices" for the handling of medication. "NCAA members have decided that it is their individual responsibility to assure compliance with appropriate medication and treatment guidelines," said the statement.
"If we keep track of what happens to, let's say, horses in horse racing, don't we owe it to the athletes to keep track of what's going on in college sports?" asked Professor Caplan.