It can be caused by capillary spasm or insufficient blood filling in the skin, as well as by a decrease in the amount of erythropoietin in the blood (anemia), and can be seen in cold, panic, deficiency, aortic valve incomplete closure, anemia, and internal bleeding. In addition, strong capillary constriction due to hemorrhage, shock, hypothyroidism, chronic nephritis, lead poisoning, etc. can also cause pallor of the skin and mucous membranes. Pale skin, nails, mucous membranes and weakness and sleepiness should be alerted to anemia. Anemia is caused by the body’s inability to make enough hemoglobin (a protein that carries oxygen to blood red blood cells and various tissues in the body). When this happens, a person may feel weak and exhausted, depressed and irritable. Other symptoms include fatigue, dizziness, fainting, apathy, irritability, decreased ability to concentrate, and an unbearable feeling of cold. Almost 20 percent of women are at risk for anemia.