Culpepper, almost a contemporary of Shakespeare's, was in no doubts as to the beneficial nature of hemp, along with many other herbal remedies that today we have forgotten (or are only just rediscovering, as in the case of hypericum and Evening Primrose...).
Thus if he did smoke dope, it was probably for a specific reason rather than simply to get stoned. I dare say he enjoyed the side effects though...

(and what was it called before Bruce Robinson invented the Camberwell Carrot?)