Gateway drug theory

The gateway drug theory (also called gateway theory, gateway hypothesis and gateway effect) states that use of less deleterious drugs precedes, and can lead to, future use of more dangerous hard drugs or crime. It is often attributed to the earlier use of one of several licit substances, including tobacco or alcohol, as well as cannabis.

The reverse gateway theory posits that earlier regular cannabis use predicts later tobacco initiation and/or nicotine dependence in those who did not use tobacco before.

Cannabis

The hypothesis is that the use of soft drugs like cannabis leads to the use of harder drugs via a sequence of stages. This is based on the observation that many consumers who use cocaine or heroin have previously used cannabis, and most have used alcohol or tobacco; the hypothesis is that progression of drug use initiation continues from there to other drugs like cocaine or heroin. Some research supports that cannabis use predicts a significantly higher risk for subsequent use of "harder" illicit drugs, while other research does not. Some research finds that even alcohol represents a "gateway" drug, leading to the use of tobacco, marijuana, and other illicit substances.