Dr. Ashton concluded that people needed to slowly reduce the dose of their medication, sometimes over the course of six months or more. She explained this strategy in her manual, using examples from patients she had treated herself.

“Her work both honored her patients and turned out to be more helpful than any randomized, controlled trial,” said Dr. Anna Lembke, an associate professor of psychiatry and behavioral sciences at Stanford University, where she leads the school’s Stanford Addiction Medicine Dual Diagnosis Clinic.

Dr. Ashton’s work was also timely. Scientists were starting to realize that patients who became dependent on benzodiazepines often misused opioids as well. One study found that the overdose death rate among patients taking both benzodiazepines and opioids was 10 times higher than among those who only took opioids.

But unlike opioid prescriptions, which started declining after 2012, benzodiazepine prescriptions continued to rise. Doctors still had limited awareness of benzodiazepines’ addictive potential and some patients could continue on the same steady dose for years without exhibiting any symptoms or obvious changes in behavior.

“If patients take them only as prescribed by their doctor, then they don’t meet criteria for addiction, because addiction involves behaviors that correspond to compulsive drug-seeking,” Dr. Lembke said. “But really, if you look at what’s happening in the brain, it’s probably not that different.”

In 2013, the British National Formulary, which advises doctors on prescribing practices, updated its guidelines to recommend benzodiazepines for short-term use only and to suggest a withdrawal schedule based on Dr. Ashton’s manual. In 2018, it revised its recommendations again to suggest an even slower withdrawal, based on evidence that Dr. Ashton and other researchers had collected.

The United States followed suit, with the Food and Drug Administration requiring that all benzodiazepines carry a so-called black-box warning about the drugs’ side effects, and that doctors check their state’s prescription drug monitoring program to see whether a patient had been given any federally controlled and addictive medications in the past 12 months.