• Opioids, or narcotics, are the most powerful pain medicines. Opioids commonly prescribed include morphine, methadone, and oxycodone.  ide effects include:
• nausea
• vomiting
• feeling drowsy
• difficulty having a bowel movement
  

If you take an opioid drug for more than a week or two (and, for some people, as little as a few days), you can become physically dependent on the drug. This means that you will have withdrawal symptoms when you stop taking it. Withdrawal symptoms include nervousness, diarrhea, and tremor, or shaking. Physical dependence on opioids is a normal response to taking the drugs and not something to be overly concerned about. Physical dependence is not the same as addiction. Addiction to opioids means that you crave opioid drugs and feel driven to take them for reasons other than easing your pain. When taken properly, the chances of becoming addicted to opioids are low.

Early research suggests that women's pain responds better than men's to a class of opioids called kappa opioids. This suggests that male and female brains handle pain signals in different ways. It also suggests that kappa opioids might be an option for women in pain who do not respond well to typical opioids. More research is needed in this area.

Researchers are also working on developing opioid medicines that hopefully will not be addictive and will have fewer side effects. Some of these are showing promise in research on animals. But none are yet available for use in humans.

• Antidepressants and anticonvulsants. Some medicines used to treat depression can treat some painful conditions, including migraine and tension headaches. In a way, this is not surprising, because we know that the part of the brain where pain is processed is also involved in depression. Pain can make depression worse, and depression can make your pain worse. So if you are in pain and also are depressed, you need to treat depression and pain at the same time.
  
  Other medicines that have been used for treating certain types of pain are anticonvulsants. These medicines were developed to treat epilepsy. But they are sometimes useful for treating painful conditions caused by damage to the nervous system.