What are the risks of using prescription opioids for pain, especially chronic pain?

The two most serious risks are overdose and addiction. In addition to the serious risks of overdose and addiction, prescription opioids can have a number of side effects longer-term, even when taken as directed. These include tolerance (needing to take more of a medication for the same pain relief) and physical dependence (having symptoms of withdrawal when the medication is stopped). Other side effects may include increased sensitivity to pain, constipation, nausea, sleepiness, confusion and depression.