Victoria Toline would hunch over the kitchen table, steady her hands and draw a bead of liquid from a vial with a small dropper. It was a delicate operation that had become a daily routine — extracting ever tinier doses of the antidepressant she had taken for three years, on and off, and was desperately trying to quit.

“Basically that’s all I have been doing — dealing with the dizziness, the confusion, the fatigue, all the symptoms of withdrawal,” said Ms. Toline, 27, of Tacoma, Wash. It took nine months to wean herself from the drug, Zoloft, by taking increasingly smaller doses.

“I couldn’t finish my college degree,” she said. “Only now am I feeling well enough to try to re-enter society and go back to work.”

Long-term use of antidepressants is surging in the United States, according to a new analysis of federal data by The New York Times. Some 15.5 million Americans have been taking the medications for at least five years. The rate has almost doubled since 2010, and more than tripled since 2000.