To put it simply, both qi and blood are substances in the human body, and qi deficiency is the lack of such substances in the human body. Blood deficiency means that blood can't circulate smoothly, not lack. Generally, qi and blood are interdependent, one side is weak, and the other side will soon be weak. For example, qi deficiency can not promote blood circulation, and the strength of blood will be greatly reduced, and qi and blood will be weak. Therefore, people often say that both qi and blood are deficient because they are inseparable. If you want to solve the problem of deficiency of both qi and blood, you need to nourish qi and blood. From the perspective of traditional Chinese medicine, there are many reasons that can lead to deficiency of both qi and blood, such as yin deficiency with internal heat and yang deficiency with internal cold. However, these two pathologies are completely different. Therefore, Chinese medicine pays attention to dialectics, finds the root cause of deficiency of both qi and blood and solves it, and deficiency of both qi and blood will naturally recover. Otherwise, if you simply replenish qi and blood, the root cause of deficiency of both qi and blood will not be solved, and even if you temporarily replenish qi and blood, you will soon become weak again.