Chronic cocaine use can lead to feelings of paranoia and anxiety, severe breathing problems and heart failure. Chronic speed users may experience intense emotional disturbances, like anxiety, fear, and even mental illness. Speed lowers the body's natural defenses against disease. Chronic speed users often don't eat enough, which can cause malnutrition and severe weight loss. Chronic speed use can cause high blood pressure and heart failure.
Some people believe marijuana has medicinal properties that help people with serious diseases.
Marijuana can also be addictive, however. Chronic marijuana use can cause confusion, fatigue and forgetfulness. Smoking marijuana can lead to lung diseases like bronchitis and cancer. Although the long-term effects of ecstasy are unknown, ecstasy use has been linked to liver failure and brain damage. There have been several reported deaths since 1988 associated with ecstasy.