To become a blood donor, you must be 18 years of age (16 and 17 with parental consent), weigh at least 110 pounds, be free of cold and flu symptoms and in general good health.
In order to keep the blood supply safe, the U.S Food and Drug Administration (FDA) also requires blood centers to implement additional eligibility criteria. View more eligibility requirements (like tattoos and common travel deferrals) here.