According to the Family Practice Notebook, Ritalin immediate-release pills start working within 20 minutes to an hour from the time of the dose. Doctors prescribe Ritalin to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy, among other medical conditions.
The Family Practice Notebook explains that different formulations of methylphenidate, the drug in Ritalin, differ with respect to how long they take to start working. Ritalin-SR, a long-acting formulation, starts working within 90 minutes and lasts for around five to eight hours, which is two to five hours longer than the immediate-release formulation. The longest-lasting formulation, Concerta, starts working one or two hours from the time of the dose but lasts for 12 hours.