Anemia is a common medical condition in which the body does not have enough healthy red blood cells to carry oxygen throughout the body. This can result in fatigue, dizziness, shortness of breath, headaches, and an irregular or rapid heartbeat. Anemia can be caused by a variety of factors, including a lack of iron in the diet, chronic illnesses such as kidney disease or cancer, or blood loss due to injury or surgery. It can also be caused by certain medications or inherited conditions.