The school has declined to release the names of the players being treated. It said in a statement released Tuesday that the players were taken to University of Iowa Hospitals and Clinics on Monday night. They are responding well to treatment and are in safe and stable condition, according to the school.
Iowa spokesman Steve Roe said privacy laws prevent officials from further comment.
"Coach Kirk Ferentz is out of town recruiting, but he is aware of the situation and is being kept abreast of the progress being made," Iowa athletic director Gary Barta said in a statement. "Our No. 1 concern is the safety of our student-athletes, so we are pleased with the positive feedback. Our next step is to find out what happened so we can avoid this happening in the future."
Iowa offensive lineman Julian Vandervelde, who recently graduated from the program and was a member of the team's leadership group, defended the Iowa's workout practices in an interview with The Associated Press.
"They are nothing if not concerned for the health of the players," Vandervelde said. "That's always the first priority, health and development. I mean workouts are never used to punish. It's always about improvement, and workouts are always well within the capabilities of the athletes asked to perform them."
Tuesday's announcement that a dozen players had been hospitalized was just the latest bad news to hit the program that just wrapped a disappointing 8-5 season.
Senior wide receiver Derrell Johnson-Koulianos was suspended for the Hawkeyes' Insight Bowl win over Missouri after an arrest on drug charges. Johnson-Koulianos pleaded guilty to marijuana possession while other drug charges against him were dismissed.
Running back Adam Robinson was dismissed from the team after being arrested for possession of marijuana in his hometown of Des Moines while on suspension for violating team rules.
