Polysubstance abuse is defined as abusing three or more substances for a period of 12 months or more. Polysubstance abuse is a common problem in teenagers, and usually begins with substances like tobacco, marijuana, or alcohol. Three of the following symptoms must be shown during a 12-month period to receive an official diagnosis of polysubstance dependence:

Tolerance. The user has to keep using more and more of a substance at one time to get high because the usual amounts are less effective.

Withdrawal. The user shows withdrawal symptoms when drugs stop being used; or the drug is used specifically to prevent withdrawal symptoms.

Inability to stop using/Loss of control. Repeated use of more drugs than planned. The user has unsuccessfully attempted to cut down or stop using the drugs or shows a persistent desire to stop using, but cannot.

Time. The person spends a lot of time studying drugs, obtaining drugs, using drugs, being under the influence of drugs, and recovering from the effects of drugs.

Interference with activities. The user has reduced the amount of time involved in recreational activities, social activities, and/or work because of the use of drugs.

Harm to self. The person continues to use substances despite having a noticeable physical or psychological problem caused by or made worse by the use of drugs.