The main causes of bilateral leg edema are physiological, malnutrition, cardiogenic, nephrogenic, hepatogenic, endocrine, lymphatic reflux obstruction, drugs, and idiopathic edema. 1. Physiological causes of edema of legs, such as standing for a long time, overwork, lack of sleep and so on. 2. Edema due to malnutrition. Long-term protein intake is insufficient or malignant tumors and other chronic wasting diseases lead to the reduction of plasma albumin, colloid osmotic pressure is reduced, so that the tissue interstitial fluid collects in the lower limbs and causes edema. 3. Cardiogenic edema. Chronic obstructive pulmonary disease, pulmonary arterial hypertension, pulmonary heart disease and other causes of right heart failure, venous pressure increases, fluid leakage into the tissue interstitial space, causing edema of the legs. 4. Nephrogenic edema. Acute and chronic nephritis and other renal diseases lead to decreased renal blood flow, sodium retention, increased capillary permeability, protein discharge with urine, plasma colloid osmotic pressure decreases, and interstitial fluid leakage into the tissues, resulting in bilateral leg edema. 5. Endocrine edema. Hypothyroidism, Cushing’s syndrome, primary aldosterone syndrome, etc. lead to mucous edema, causing bilateral leg edema. 6. Lymphatic reflux obstruction type edema. Embolic phlebitis of the lower limbs, lymphangitis, filariasis, etc. lead to obstruction of venous lymphatic reflux in the lower limbs, and body fluids enter into the tissue interstitial space, resulting in edema of the legs. 7. Calcium antagonists, adrenocorticotropic hormones and other drugs may cause adverse reactions to bilateral leg edema. 8. Idiopathic edema. Women in late pregnancy, premenstrual tension syndrome can cause idiopathic bilateral leg edema. When there is unrelieved double leg edema, you need to consult a doctor in time, under the guidance of the doctor to clarify the cause of the disease, and then treat the cause of the disease.