In his late 20s, Christopher Milford of East Boston, Mass., got high on some OxyContin his friend gave him.
By the time he was in his early 30s, he was shooting heroin and Suboxone.
Milford would reuse the same needle for a week or more. Then, one day, he was so sick he couldn't get out of bed.
"It felt like the worst flu I ever got in my life," he says. "It almost felt like a dream. I started doing weird things like putting PlayStation controllers in the sink in the bathroom. It was just weird, off the wall."