The difference between kidney yin deficiency and kidney yang deficiency is mainly based on clinical symptoms. Kidney yin deficiency is mainly characterized by deficiency heat, while kidney yang deficiency is mainly characterized by deficiency cold. 1. Kidney yin deficiency: mainly manifested as five heart-heat (heat in the hearts of the hands and feet, and self-consciousness of the heart and chest), hot flashes (a burst of heat), night sweating (abnormal sweating after going to sleep, and waking up after sweating stops), lumbar and knee pain, vertigo and tinnitus, insomnia and dreaming, spermatorrhea in men, and menorrhagia or amenorrhea in women. 2. Kidney yang deficiency: mainly manifested as lumbar and knee soreness (the feeling of lumbar and knee soreness and weakness), cold and pain, or male impotence, premature ejaculation, infertility in women’s uterus, loss of libido, or prolonged defecation of stools, undigested food in the stools, pre-dawn abdominal pain and diarrhea, pale or dark face, fear of cold, body temperature, depression, urination or nocturnal urination, and other symptoms. Clinicians should be consulted to differentiate between kidney yin deficiency and kidney yang deficiency.