Can Marijuana Use Prevent You From Giving Blood? CBD Cannabis and voluntary blood donations: what is the rule? Justbob We all know smoking and vaping isn't great for your health. But it doesn't stop you from being a blood or plasma donor. Just make sure to wait one hour after donating We all know smoking and vaping isn't great for your health. But it doesn't stop you from being a blood or plasma donor. Just make sure to wait one hour after donating