Can You Donate Blood or Plasma if You Use Cannabis? Teen Vaping: What Parents Can Do Children's Hospital Colorado Myth: You can't donate blood if you smoke or drink. Fact: Smoking or occasional drinking doesn't automatically disqualify you. But avoid alcohol for at least 24 hours before donating to Smoking (or vaping) doesn't affect your ability to donate blood. Help us bust this myth by sharing our post. Smoking (or vaping) doesn't affect your ability to donate blood. Help us bust this myth by sharing our post.