For a while, walking the dog felt hazardous.

Earl Vickers was accustomed to taking Molly, his shepherd-boxer-something-else mix, for strolls on the beach or around his neighborhood in Seaside, Calif. A few years ago, though, he started to experience problems staying upright.

“If another dog came toward us, every single time I’d end up on the ground,” recalled Mr. Vickers, 69, a retired electrical engineer. “It seemed like I was falling every other month. It was kind of crazy.”

Most of those tumbles did no serious damage, though one time he fell backward and hit his head on a wall behind him. “I don’t think I had a concussion, but it’s not something I want to do every day,” Mr. Vickers said, ruefully. Another time, trying to break a fall, he broke two bones in his left hand.

So in 2022, he told the oncologist who had been treating him for prostate cancer that he wanted to stop the cancer drug he had been taking, off and on, for four years: enzalutamide (sold as Xtandi).

Among the drug’s listed side effects are higher rates of falls and fractures among patients who took it, compared with those given a placebo. His doctor agreed that he could discontinue the drug, and “I haven’t had a single fall since,” Mr. Vickers said.

Public health experts have warned of the perils of falls for older people for decades. In 2023, the most recent year of data from the Centers for Disease Control and Prevention, more than 41,000 Americans over 65 died from falls, an opinion article in JAMA Health Forum pointed out last month.