Ty Dolla $ign says It's Time Rappers Give Up on Lean

Ty Dolla $ign's got some advice for Lil Wayne ... whether he takes it is another story.

Ty was leaving TAO Monday night when we asked him about the codeine cough syrup concoction Weezy can't seem to get enough of. TMZ broke the story ... Wayne suffered multiple seizures this weekend and was hospitalized in Chicago, which forced the cancellation of a Vegas gig.

Dolla's crystal clear on how he feels about lean ... but it's apparent he subscribes to the "do you boo boo, do you" theory.