Normal human blood should be bright red in color, but the color of the blood can vary slightly depending on the oxygen level. In fact, you may have seen some people with purple lips and mouth, often these people are hypoxic, including some old slow-onset, perennial smokers, or some people with chronic heart disease, such as cardiac insufficiency, rheumatic heart disease, or when the heart function is not good, that is, when the lack of oxygen is more serious, the blood color will often be darker, more purple lips, mainly related to the oxygen content of the blood. Patients often need to be given active oxygen support, including oxygen. There are actually some devices at home to administer oxygen, and there is also the need to actively treat the primary disease and improve heart function or lung function, and the color of the blood will improve.