If an applicant has drug problems, it could be an issue during the medical exam. One of the things the medical exam is looking for is evidence of drug abuse or addiction. If the drug abuse was in the distant past and there is no recent issue with it, you are more likely to get approved. However, if they are suspicious that it’s an ongoing current problem, you can be denied.
When it comes to immigration, “drug abuse” has a wider definition than normal use. We have had customers denied a visa after simply testing positive for marijuana use in a blood test. If you’re a “casual” drug user, it’s best for your visa’s case if you simply put that hobby to sleep months before your medical exam. The stakes are too high.
In a more recent update, the Trump Administration has issued an USCIS policy update denying citizenship to individuals who use marijuana, even if they live in a state where recreational or even medical marijuana is legal. See this article for more information.