One of the most frequent reasons people go to the doctor is for pain relief. There are a number of different drugs that can ease pain.
Opioids -- also called opiates or narcotics -- are pain relievers made from opium, which comes from the poppy plant. Morphine and codeine are the two natural products of opium. Synthetic modifications or imitations of morphine produce the other opioids:
Percocet, Percodan, OxyContin (oxycodone)
Vicodin, Lorcet, Lortab...