Fen 72 is 3 day detox pill, designed to take in conjunction with Fenphedra. Fenphedra is a popular “celebrity diet pill” that has been linked with some incredible weight loss results. Fen-72 is no different when it comes to its weight loss effects. Fen-72 is a free 72 hour detox that comes when you order Fenphedra and is not available any where else.