Gabriel Olsen / FilmMagic 1 / 8
Gabriel Olsen / FilmMagic 1 / 8

John Stamos had the drug GHB in his system when he was arrested last June for driving under the influence.

A criminal case will be filed soon charging John with DUI for GHB (known by many as the date-rape drug). Sources close to the actor say John was using the drug as a fitness supplement.

The "Fuller House" star was arrested in June when police spotted him driving erratically in Beverly Hills, California. He was so heavily under the influence that he was taken to the hospital.

TMZ is reporting that aside from GHB, he also had another non-narcotic drug in his system.

GHB is often used (illegally) for body building to get lean muscle. It also helps muscles recover because of the level of sleep one can get, which is the same reason that it is known as the so-called date rape drug.