Wikipedia has a detailed and well researched article on the Opioid epidemic.
The article covers a wide range of aspects, including causes, effects, demographics, and how the US federal, state and local governments reacted to the crisis.
While certainly a worldwide phenomenon, the majority of opioids are consumed within the United States.
Source: “Opioid Data Analysis and Resources. Drug Overdose”. CDC Injury Center. Centers for Disease Control and Prevention.
There is a section on treatment and the dual role of medication and behavioral treatment.
Behavioral treatment is less effective without medical treatment during the initial detoxification. It has similarly been shown that medical treatments tend to get better results when accompanied by behavioral treatment. For opioid dependence, popular non-pharmacological treatment options include cognitive behavioral therapy (CBT), group or individual therapy, residential treatment centers, and twelve-step programs such as Narcotics Anonymous. Since addictive behavior is a learned behavior in opioid dependence, cognitive behavioral therapy aims to promote positive motivation to change that behavior.
Other interesting quotes:
The current disparity in accessibility to pain relief in various countries is significant; the U.S. produces or imports 30 times as much pain relief medication as it needs while low-income countries such as Nigeria receive less than 0.2% of what they need, and 90% of all the morphine in the world is used by the world’s richest 10%.
Several of the charts and newspaper articles have been covered here before, including the rise in opioid overdose deaths as well as the reduction in US life expectancy since 2015. The article cites more than 200 reference links to other studies and articles. Overall well worth a read.