A partial hospitalization program (PHP) is another type of structured outpatient program that is very similar to IOT. However, whereas IOT consists of between 6 and 9 hours of treatment per week, a PHP consists of at least 20 hours of treatment per week. A person undergoing PHP treatment is under supervision for most of their time in treatment, typically spending their days in care and their nights at home. Medical professionals initially designed PHP to treat people with mental health conditions. However, treatment centers for substance use have since incorporated PHP into their rehabilitation programs. People typically enter into PHP following inpatient treatment or detoxification. Following PHP, a person may progress to IOT. This may happen if a person’s symptoms are manageable, but they continue to require some form of structure and support.