Listed below, you'll find information on some of the most popular illicit drugs in addition to their short- and long-lasting effects. When it comes to seeking treatment, there are many alternatives to consider. You need to try to find a treatment center that provides a complete continuum of care and a variety of evidence-based treatments.Of the 27.1 million people who said they had used illicit drugs in the past month in 2015, more than 22.2 million reported utilizing cannabis. The variety of people 12 and older who utilized heroin in the past year increased from 404,000 in 2002 to 681,000 in 2013. The usage of other illicit drugs, such as cocaine, meth and hallucinogens, has remained mostly the exact same since the mid-2010s.