Because only a small amount of bone marrow is removed, donating usually does not pose any significant problems for the donor. The most serious risk associated with donating bone marrow involves the use of anesthesia during the procedure.
The area where the bone marrow was taken out may feel stiff or sore for a few days, and the donor may feel tired. Within a few weeks, the donor's body replaces the donated marrow; however, the time required for a donor to recover varies. Some people are back to their usual routine within 2 or 3 days, while others may take up to 3 to 4 weeks to fully recover their strength.
This answer is based on the source infromation from the the National Cancer Institute