There are no credible reports of President Donald Trump's previous history of drug use and neither are there any that show that he is a drug addict.
News sources report that during a press conference at the White House, Adderall truthers found a smoking gun. The viral thread of tweets stated that a white projectile blasted out of Trump's nose. However, none of those allegations have been proven to be true in a credible enough investigation/report. Thus, the allegations of drug abuse by the U.S. President cannot be currently verified.