Spleen and kidney yang deficiency (deficiency of yang qi in the spleen and kidneys) is usually caused by the depletion of yang qi in the spleen and kidneys as a result of prolonged illness. Spleen and kidney yang deficiency caused by prolonged illness and the patient’s own physical weakness is more difficult to cure, but it can usually be cured with symptomatic treatment under the guidance of a doctor. Spleen and kidney yang deficiency is mostly caused by prolonged illness of the spleen and kidney, which depletes qi and injures yang; or the patient has diarrhea for a long time, or there is a watery evil within the body for a long period of time, which leads to the decline of kidney yang and fails to nourish spleen yang; or the spleen yang is deficient for a long time, which fails to nourish kidney yang and ultimately results in the injury of yang qi of the spleen and kidneys. Spleen and kidney yang deficiency is often manifested clinically as cold limbs, lumbar and knee weakness (a feeling of soreness and weakness in the waist and knees), cold pain in the abdomen, diarrhea for a long period of time, dysuria (unruly urination), swelling, or frequent urination, or frequent nocturnal urination, and so on. Since Spleen and Kidney Yang Deficiency (deficiency of yang qi in the spleen and kidneys) is mostly caused by prolonged illness, it is more difficult to cure.