How long does it take for ritalin (methylphenidate) to become effective?

Noticed effects: Most teachers or parents will notice some effect of Ritalin (methylphenidate) within a few days if not the first day. If the dose is a bit low there may not be much of an effect & at high doses the kid may appear drugged & slow. The concept of effectiveness can be a different issue. The med may allow more settled participation in class but it will not fix any co-existing learning problems.