Polysubstance Abuse and Dependence.
Many people who use drugs try a variety of substances and settle on a"drug of choice," but use of multiple substances by those who use drugs is most common. Multiple drug use or abuse, commonly referred to as polysubstance use or abuse, is also likely to occur in individuals who progress through use or dependence on a variety of drugs over time. For example, some people start use/abuse with nicotine, caffeine, or alcohol. If they continue on to use other drugs, they often try cannabis, followed by stimulants, hallucinogens, or other CNS depressants. This differs from young people who consume any drug readily available at a party. The ingestion of multiple substances at the same time creates additional risks because of chemical drug interactions or potentiating effects.
Although individuals mix any combination of substances, some drug mixtures are more likely to occur. Those individuals with alcohol dependence are more likely to use or develop nicotine dependence. Those who are cocaine dependent are more likely to become dependent on alcohol. Some people who use opioids combine heroin and cocaine in a mixture called a speedball. The combination both enhances the effects and decreases the side effects of both drugs.Other combinations of multiple drug ingestion exist ( Schuckit,200)