Making and selling beverages that combine alcohol with caffeine has effectively been banned.
The Food and Drug Administration has called the combination "unsafe" and a "public health concern."
The drinks are often referred to as a "blackout in a can", with alcohol contents as high as 12-percent and as much caffeine as a cup of strong coffee.
Their potency and popularity among the college crowd has been known to send relatively novice drinkers to the emergency room.
"It's not unusual to see college students with alcohol levels double or even perhaps triple of what is legally drunk," says Dr. Mary Claire O'Brien of Wake Forest University's Baptist Medical Center.
In 2007 Dr. O'Brien published the first research project to discover a link between caffeinated alcoholic beverages and injuries.
She found those who mixed alcohol with caffeine were likely to drink more and more often.
"If you drink them at the same time, you don't realize you're drunk and you keep drinking," she explains.
The Food and Drug Administration has been following such research for a year and on Wednesday sent warning letters to four manufacturers of caffeinated alcoholic beverages saying that adding caffeine to alcohol is "unsafe."
Phusion Projects is one of those companies.
It makes "Four Loko."
Just before the FDA warning letters were issued Phusion Projects said it will remove caffeine and other stimulants from its "Four Loko" drinks, but said in a statement:
"We are taking this step after trying -- unsuccessfully -- to navigate a difficult and politically-charged regulatory environment at both the state and federal levels."
Caffeinated alcoholic drinks have already been banned in five states.
The other companies to receive warning letters are United Brands Company, New Century Brewing Company and Charge Beverages.
While the companies will have time to respond, the FDA says the government could seize the products if the companies continue to make them.