"Jen is recovering fully and speedily," spokeswoman Lacey Wickline told Reuters.
Wickline said the medication had been prescribed for Capriati by her doctor but did not elaborate.
The Palm Beach Post reported that an ambulance crew rushed Capriati, 34, from her apartment in a hotel-condominium building in Riviera Beach, Florida, to St. Mary's Medical Center in West Palm Beach early on Sunday.
Her father Stefano Capriati told TMZ on Sunday that she was recovering well.
Capriati, formerly the top-ranked women's tennis player in the world who won 14 career titles, including three Grand Slams, and a gold medal at the 1992 Olympics, has a history of drug problems.
In 1994, at the age of 18, she voluntarily entered a drug and alcohol rehabilitation center two days after her arrest on a misdemeanor charge of marijuana possession.