First of all, thank you for considering being a bone marrow donor! Bone marrow donations are life saving for many critically ill patients with cancers and other blood disorders, but access to this treatment is sometimes limited by a lack of willing donors like yourself!
Generally speaking, bone marrow donation is safe. It is a surgical procedure, which requires withdrawing bone marrow from a bone in your body with a large needle under sterile condition. This procedure would be painful if performed without medications, therefore the bone marrow donation is usually performed with anesthesia.
Therefore, the main risks from donation are related to side effects from the anesthesia medications. The doctors
who run the bone marrow donation program work very hard to ensure your safety, and they perform a thorough physical examination prior to allowing you to donate, which is designed to detect any medical problems (such as a heart condition) that might make anesthesia dangerous. Therefore, if you have been medically cleared by these doctors to donate, then the risks are very low, as they would not allow you to proceed with the donation if they had any concerns.
Talk to your primary care doctor
or to your local bone marrow transplant program if you have more questions!