The reason for the swelling of the legs in summer is that the tissue fluid penetrates deep into the interstices below the tissues, and the tissue fluid is mainly formed by the blood plasma filtering through the capillary walls. When the day is hot, the capillaries will expand when it is colder than when it is hot, and the leakage of tissue fluid will increase, resulting in leg swelling in the lower limbs. You can reduce the standing time, elevate your legs when resting or sleeping, and put a pillow under your legs to relieve it. Pay more attention to rest and try to eat a diet based on high-quality protein, which can increase the colloid osmotic pressure in the capillaries to reduce the exudation of tissue fluid. In addition, people with poor heart function can easily form double lower limb edema, which is due to poor heart function and insufficient return blood volume, which forms stagnation in the lower limbs. Elevated venous blood pressure in the lower extremities leaks excess fluid into the interstitial tissues, and in this case it is recommended to be admitted to the cardiology department of a regular hospital for conditioning. Edema of the lower extremities is rarely seen in patients with hypothyroidism, and some patients with hypothyroidism may have mucinous edema of the anterior calves of both lower extremities.