Heavy use may also lead to cancer of the respiratory tract, high blood pressure, immune system depression, and sterility. Many marijuana users also smoke cigarettes so their risk of lung cancer and emphysema increases. In fact, one marijuana cigarette causes lung damage equal to that of 25-30 nicotine cigarettes. Opiates Opiates or narcotics, like heroin, codeine and morphine are used to relieve pain but are often abused. Opiates can come in the form of powder, pills, or solutions.
Opiates act on the respiratory center of the brain and reduce hunger, thirst, pain, and sex.
Heroin, the most abused opiate in the United States, can be injected or inhaled. A person uses heroin to escape from problems or to relax. There is an immediate rush after injecting it but the effects wear off in 3-4 hours. After taking it, a person's face flushes, pupils constrict, and feeling of well-being is enhanced. Later on, drowsiness kicks in.