Individuals progress through drug addiction treatment at various speeds, so there is no predetermined length of treatment. However, research has shown unequivocally that good outcomes are contingent on adequate lengths of treatment. Generally, for residential or outpatient treatment, participation for less than 90 days is of limited or no effectiveness, and treatments lasting significantly longer often are indicated. For methadone maintenance, 12 months of treatment is the minimum, and some opiate-addicted individuals will continue to benefit from methadone maintenance treatment over a period of years.
Good outcomes are contingent on adequate lengths of treatment.

Many people who enter treatment drop out before receiving all the benefits that treatment can provide. Successful outcomes may require more than one treatment experience. Many addicted individuals have multiple episodes of treatment, often with a cumulative impact.