Other people have already pointed out that Meth and Ritalin are not chemically similar, and that Meth is sometimes used as a prescription drug. I think a lot of people are missing the main point though-
Meth is usually made in a garage, while Ritalin is made in a lab.
Something you buy on the street will have a varying dose, it could have additives that will kill you or make you sick, it could be completely fake. It is also not usually measured out properly by the user.
A prescription medication made by a company and taken as directed by a doctor is much safer.
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