When I take Ritalin, I need to take an initial dose of 15-20mg for it to be effective (and then taper it down every 50 minutes otherwise I get jittery). But when I was on Concerta, 18mg was not enough, even though it is roughly the same dosage. Is the Concerta dosage not comparable to that of the Ritalin as it is spread out over a longer period? I know 30mg of Ritalin would be way too much for me – but does that necessarily mean that 36mg of Concerta would too?