Before she made the mistake, before spasms rocked her body, before doctors raced to save her life, Rachel was cleaning out her car. That morning in 2012, as she dug through some junk in the backseat, she found a small bottle of pills. Her psychiatrist had handed her the drug sample months earlier—to try in times of "acute anxiety"—and Rachel had tossed it into her Prius and forgotten all about it. Now, however, it seemed like a godsend.

Then in her midthirties, Rachel had been laid off from her gig at a major Bay Area tech company. Jobs were scarce, and paying her mortgage was becoming difficult. Adding insult to injury, she'd just found out that her former Mr. Right, the man she'd dated for years, was marrying a mutual friend. The sight of the pills seemed to bring her misery into sharp focus. Her situation suddenly felt acutely acute.