Because of the clamor for the drug, and concern over the striking number of overdoses involving Xanax here and across the country, Seven Counties took an unusual step — its doctors stopped writing new prescriptions for Xanax and its generic version, alprazolam, in April and plan to wean patients off it completely by year’s end.

Thus began a troubled toddler’s journey from one doctor to another, from one diagnosis to another, involving even more drugs. Autism, bipolar disorder, hyperactivity, insomnia, oppositional defiant disorder. The boy’s daily pill regimen multiplied: the antipsychotic Risperdal, the antidepressant Prozac, two sleeping medicines and one for attention-deficit disorder. All by the time he was 3.

He was sedated, drooling and overweight from the side effects of the antipsychotic medicine. Although his mother, Brandy Warren, had been at her “wit’s end” when she resorted to the drug treatment, she began to worry about Kyle’s altered personality. “All I had was a medicated little boy,” Ms. Warren said. “I didn’t have my son. It’s like, you’d look into his eyes and you would just see just blankness.”