Long hours in a car, the lower limbs can appear swollen, medically known as “traveler’s edema”. Therefore, when riding in a car, do not always sit, should always change the position, or stand for a while or elevate the lower limbs to sit for a while, also can be used to massage the lower limbs from top to bottom to help blood flow back. The following diseases are also causes of edema in travelers: 1. hereditary angioedema Hereditary angioedema (hereditary angioedema) is a disease with a family history of recurrent acute limited edema of soft tissues. It is autosomal dominant, and its attacks are related to minor trauma, mood swings, infections, sudden changes in temperature, as well as menstruation and estrogen-based contraceptives. 2.Lymphedema Lymphedema refers to the soft tissue fluid caused by the obstruction of lymphatic flow in certain parts of the body after repeated infections on the surface of the body. This disease is called “nameless swelling” in Chinese medicine. 3, measles Measles is one of the most common acute respiratory infections in children, which is highly contagious and prone to epidemics in densely populated areas without universal vaccination, with pandemics occurring once every 2 to 3 years. 4, urticaria and angioedema Urticaria and angioedema, also known as rubella and angioneurotic edema, can occur separately or simultaneously; they manifest as non-indentation edema of the skin and sometimes involve the mucosa of the upper respiratory tract or gastrointestinal tract. Urticaria damages only the superficial layers of the skin and presents as a red, plucky-edged, central pale mass of rash that sometimes fuses into a giant wind cluster. In angioedema, the lesions involve the deeper layers of the skin (including the subcutaneous tissue) and appear as easily identifiable limited edema. All of these manifestations can appear and disappear rapidly on a momentary basis. Recurrent episodes not exceeding 6 weeks are acute, and the reaction is chronic. 5.Lymphatic edema of the extremities Lymphedema refers to a pathological state in which the return of lymphatic fluid is obstructed and refluxed in a part of the body due to a defect in the lymphatic system, resulting in the accumulation of body fluid in the superficial soft tissues of the extremities, followed by fibrous connective tissue hyperplasia, fat sclerosis, fascial thickening and thickening of the entire affected extremity. 6, generalized mucinous edema (generalized myxedema), also known as true mucinous edema (true myxedema), is produced by thyroid insufficiency resulting in reduced or lack of thyroxine secretion. Clinical manifestations include cretinism, juvenile mucinous edema, and adult mucinous edema.