Party beverages that go by “blackout in a can” and other monikers may soon be banned from store shelves in some U.S. states, thanks to a number of incidents that have left drinkers unconscious and with dangerously high blood alcohol levels.

The Michigan Liquor Control Commission (MLCC) last week effectively prohibited the sale of all alcoholic energy drinks after considering several studies regarding such beverages as well as concerns voiced by substance abuse prevention and parental groups, the general public, and an ongoing U.S. Food and Drug Administration (FDA) investigation. The Commission called the packaging of these products “misleading,” and an attempt to appeal to younger customers “encouraging excessive consumption while mixing alcohol with various other chemical and herbal stimulants.” The ban takes effect in early December.

The MLCC pointed out that a typical alcoholic energy drink is 24 ounces (0.7 liters) and has a 12 percent alcohol content—compared with a 12-ounce (0.35-liter) can of beer, which normally has 4 to 5 percent—plus the caffeine equivalent of five cups of coffee. Some of the beverage lines singled out for their 12 percent alcohol content were Associated Brewing’s Axis, United Brands’s Max and Phusion Projects’s Four Loko offerings. The commission concluded that a person need only consume one can of such a beverage to become intoxicated—and that because these drinks typically cost $2 to $5 per can they are “easily accessible and affordable.”

Such beverages were in the news last month when nine Central Washington University students were hospitalized following a party. The blood alcohol levels of the students—who were all under the age of 21 at the time of the incident—ranged from 0.123 to 0.35. (A blood alcohol concentration of 0.3 can be lethal.) That school and others have since banned such drinks from campus pending further investigation.

Not far from Michigan, Chicago’s City Council proposed its own ban on energy drinks that contain alcohol. Michigan and Oklahoma are the only states so far to ban such beverages, but New York is considering the same, and the Pennsylvania Liquor Control Board last week asked its licensed sellers to voluntarily stop selling and promoting alcoholic energy drinks such as Four Loko.

Whereas the combination of alcohol and caffeine is nothing new—rum and Coke, anyone?—this new breed of beverage is not meant to be sipped or served on the rocks. Scientific American asked Thomas Gould, an associate professor of psychology at Temple University in Philadelphia, to explain what happens to the body when large amounts of alcohol and caffeine are consumed simultaneously, why such drinks appeal to some drinkers, and the potential consequences of overindulgence.