<p>If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough <a href="https://medlineplus.gov/iron.html">iron</a>. Your body needs iron to make hemoglobin. Hemoglobin is an iron-rich protein that gives the red color to blood. It carries oxygen from the lungs to the rest of the body.</p> <p>Anemia has three main causes: blood loss, lack of red blood cell production, and high rates of red blood cell destruction.</p> <p>Conditions that may lead to anemia include:</p><ul> <li>Heavy periods</li> <li>Pregnancy</li> <li>Ulcers</li> <li>Colon polyps or colon cancer</li> <li>Inherited disorders</li> <li>A diet that does not have enough iron, <a href="https://medlineplus.gov/folicacid.html">folic acid</a> or <a href="https://medlineplus.gov/bvitamins.html">vitamin B12</a></li> <li>Blood disorders such as <a href="https://medlineplus.gov/sicklecelldisease.html">sickle cell anemia</a> and <a href="https://medlineplus.gov/thalassemia.html">thalassemia</a>, or cancer</li> <li><a href="https://medlineplus.gov/aplasticanemia.html">Aplastic anemia</a>, a condition that can be inherited or acquired</li> <li><a href="https://medlineplus.gov/g6pddeficiency.html">G6PD deficiency</a>, a metabolic disorder</li> </ul> <p>Anemia can make you feel tired, cold, dizzy, and irritable. You may be short of breath or have a headache.</p> <p>Your doctor will diagnose anemia with a physical exam and blood tests. Treatment depends on the kind of anemia you have.</p> <p class="">NIH: National Heart, Lung, and Blood Institute</p>