Judge Scott Millington ordered O'Neal into a two-week detox program after he admitted he had relapsed, court records show.
He was sentenced to three years' probation in June after pleading guilty to heroin and methamphetamine possession.
Neither O'Neal nor his father have been charged after being arrested Sept. 17 on suspicion of possessing methamphetamine. Deputies searched the O'Neals' home in Malibu as part of Redmond's probation and found drugs on him and in Ryan O'Neal's living area.
Ryan O'Neal's attorney has denied that any of the drugs belonged to the actor.
Ryan O'Neal, 67, was nominated for a best actor Oscar for "Love Story." Redmond is his son from a relationship with actress Farrah Fawcett.