Graft-versus-host disease (GVHD) is a common side effect of an allogeneic bone marrow transplant. An allogeneic transplant uses blood cells from a family member, unrelated donor or cord blood unit. GVHD can affect many different parts of the body including the skin, eyes, mouth, stomach, and intestines.
GVHD occurs because of differences between the cells of your body and the donated cells. Your new immune system from the donor might see your body's cells as different and attack them.