Depressants and narcotics slow down your pulse and dull your nervous system, producing a feeling of relaxation, well-being and loss of inhibitions. This can also cause you to stop breathing. These drugs are addictive.

Hallucinogenic drugs change the way people see the world. The hallucinations can be pleasant, or terrifying, depending on the hallucination, which in turn is affected by the setting and your mood and mind-set. They take about an hour to act, but the high can last for several hours. Flashbacks can occur unexpectedly for days or months afterward.

The 'come down' experienced as the drug's effect begins to fade, is different depending on what drug you have taken, how large a dose, and how often you have used the drug before. Coming down from any drug that you use frequently can cause feelings of paranoia or panic. With stimulants, the high is achieved by using up your body's own energy store, so the down is inevitable as your body becomes exhausted. Using stimulants often can cause more severe downs because your body has less time to recover between uses.