The Food and Drug Administration (FDA) has issued warnings to four companies that produce alcoholic beverages that contain caffeine, among them Phusion Projects, LLC, the producer of Four Loko. The FDA said that alcoholic drinks with caffeine additives pose "a public health concern," and indicated that it would take action if necessary, including possibly seizing inventory or imposing an injunction on production.

The FDA's announcement came Wednesday, after a year-long investigation into the health and safety risks posed by caffeinated alcoholic drinks. According to Bloomberg, 25 attorneys general had requested that the FDA examine the safety of the drinks. Several states had banned the sale of Four Loko and similar drinks prior to the FDA's announcement. Four Loko is not sold or marketed in Maine. Massachusetts instituted a ban on the sale of Four Loko and similar beverages Thursday, becoming the fifth state to take such action.

The FDA warning requires that the companies submit plans within 15 days for ending the sale and production of their affected products. In a press release, Phusion Projects indicated that it would produce a non-caffeinated variation of Four Loko in the future.