CBD Cannabis and voluntary blood donations: what is the rule? Justbob Can You Donate Plasma If You Smoke Weed? Get Facts Here! The Sanctuary Can Marijuana Use Prevent You From Giving Blood? Think you can't donate blood? Think again. Australian Red Cross Lifeblood 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