She was arrested last week at the airport after failing a security screening while trying to catch a flight to New York. A secondary search turned up needles and suspected drugs, authorities said.
Phillips' attorney, Blair Berk, told a judge Wednesday that the actress has entered rehab.
She also faces a misdemeanor count of unauthorized possession of a needle or syringe.
Phillips, 48, is out on $20,000 bail and is scheduled to be arraigned Oct.3.
She is the daughter of John Phillips, founder of the Mamas and the Papas pop group. She was fired from "One Day At a Time" in 1982 for drug-related reasons.