Polysubstance use is defined broadly as using two or more psychoactive substances. Simultaneous polysubstance use refers to the concurrent use of multiple substances. Separate polysubstance use refers to the use of muliple substances over a period, such as 12 months or the past 30 days. Nationally and in Colorado, alcohol and marijuana are the substances most commonly used in the past month. Overdose deaths due to methamphetamine and heroin were the d heroin were the most common combination of substances.
