NORMAN, Okla. -- A University of Oklahoma student died of an acetaminophen overdose, authorities said, weeks after she started taking the over-the-counter medication for a toothache. Madalyn Byrne, 19, was taking as many as nine Tylenol per day for several weeks. She died Monday at Integris Baptist Medical Center of liver damage and cardiac arrest after her roommate found her sick Sunday morning. "On Friday (she was a) perfectly healthy girl, and on Monday afternoon, she's dead," said Evelyn Byrne, the teenager's mother.She said that if her daughter could say anything to her, it would be to help make sure this type of overdose doesn't happen again."The truth is any chemical that you put in your body -- and that includes anything sold in a natural food store -- in certain conditions can be very dangerous," said Dr. Harlan Wright, from Integris Baptist Medical Center.Wright explained that acetaminophen builds up and begins a process that can poison the liver and he estimates that Byrne's liver was damaged for several days."Even if you use adequate dosage, if you add even a small amount of alcohol, it can be extremely dangerous to the liver," said Dr. Nicolas Jabbour, also of the Integris Baptist Medical Center.Byrne was on the dean's list at OU and was a member of the marching band. She was majoring in music education and Spanish.