Can you smoke marijuana after donating blood?

No. However, collection staff will treat marijuana use by a potential donor the same way as alcohol; If staff can smell marijuana or ETOH, the donor will be temporarily deferred. This has nothing to do with the drug or ETOH being present in the blood product; the small amount will have no effect on the recipient. Rather, the intoxicants, along with the volume and red cell loss, increase the risk of post donation reactions, such as dizziness, fainting, nausea, vomiting and/or (rarely) seizure activity.