At least 1 in 5 Americans live with chronic pain. Some experts put the figure at 100 million. And nearly 1 in 10 are disabled by it. America has a pain problem. To better understand it, USA TODAY spoke with more than 50 pain experts – anesthesiologists, neurologists, psychologists, geneticists and people living with chronic pain. The reporting resulted in this five-part series exploring the reality of pain, pain medications, non-drug alternatives for children and adults, and the scientific advances offering hope for the future. The opioid epidemic is inseparable from the pain crisis. Yet nothing else is as effective at treating excruciating pain. Efforts to keep opioids off the street have often gone overboard, experts say, depriving those in real need. In the first part of the series, learn about some of the causes of chronic pain – pain that lasts longer than 3 months – and the complex issues around its treatment. Click the link in bio to read more.