Chicago-based Phusion Projects, makers of Four Loko and Four Max, is being investigated by the Illinois State Attorney General for misleading marketing.
The FDA on Friday asked 30 drink manufacturers for information on their products and gave them 30 days to comply, according to a release from the AG's office.
Madigan said she is "concerned that these drinks are extremely dangerous, especially in the hands of young people" and cited recent studies that caffeine appears to mask the intoxicating effects of alcohol.
According to the FDA's Web site, the FDA has not approved caffeine in alcoholic beverages.
In 2008, the attorneys general of 13 states, including Madigan, investigated MillerCoors Brewing and Anheuser-Busch, Inc., then two leading manufacturers of alcoholic energy drinks, the release said. The investigation concluded with both agreeing to cease production; however other alcoholic energy drink manufacturers stepped in to meet demand.
In 2007, Madigan urged the Alcohol and Tobacco Tax and Trade Bureau to prevent misleading claims by alcoholic energy drinks.