If your doctor prescribed you an opioid pain reliever for pain, it's unlikely you need to worry unless you have a history of addiction issues. It's extremely rare for people
who don't already have substance-abuse issues to become addicted to pain medication.
Many pain experts think opioid pain relievers have gotten a bad rap because of media attention to addiction issues. The research shows that 2 to 6 percent of people without a history of substance abuse who are prescribed opiates for chronic pain still develop problem behaviors. However, this statistic includes people of all ages, and young people are much more likely to develop addiction issues because they're more likely to be on the medications for many years.
This misplaced suspicion of opiates is too bad, since opioid pain relievers can be very effective at relieving pain with minimal side effects or risk of organ damage, even with long-term use.
Studies of the neurobiology of pain have shown that pain relievers work differently in the brains of those in chronic pain versus those who are not actually in pain but take them to get high. And of course terminally ill patients are a different case entirely; there's no reason at all not to give opiates to relieve pain in those who are terminally ill.
When you're in pain and take opiates, the body usually experiences much less "buzz" or "high" than a person not in pain would experience. You may feel drowsy or sleepy, but you'll get used to that, and the feeling will probably go away after your body gets used to the medication.
Medically speaking, the definition of addiction is that you start experiencing cravings for the drug and begin engaging in behaviors that are counterproductive to happiness and success in order to get it. Researchers are still trying to figure out how to predict who will fall into the small category of patients who will become addicted to opioid pain relievers when taking them specifically for pain -- so the best plan is to discuss this issue with your doctor. If your family has a history of vulnerability to addiction, be sure to mention this concern. But in general, since older folks are much less likely to develop these kinds of issues, you don't need to fear addiction when taking a drug to control physical symptoms of pain.