Opiates which also have legitimate use in medicine but are commonly abused include morphine, meperidine, paregoric (which contains opium), and cough syrups that contain codeine.
Intramuscular heroin injection produces a slower onset of effects, taking several minutes to feel the intense rush users experience.
Long term marijuana users typically site using the drug to enhance positive feelings, to become calm, for stress relief and to help cope with everyday life.
The most common method of administration of crystal meth is inhalation by smoking.