The bruising on the legs of girls for no reason may be physiological, mostly seen in girls with lighter skin and more fragile skin vessels, which can be bruised by unconscious bumping, accompanied by pressure pain, which can be relieved after a few days without special treatment. In addition, it can also be caused by abnormal blood clotting, allergies and medications. If the patient is unable to determine the cause, it is recommended to go to the hospital as soon as possible to improve the blood routine, coagulation function test, etc., to clarify the cause and then carry out targeted treatment. 1, coagulation function abnormalities: common blood vessel wall abnormalities, coagulation factor deficiency, platelet reduction, etc., blood coagulation disorders, will lead to bruising of the skin of the legs and other conditions. It is recommended to seek medical attention in time for symptomatic treatment. Common drugs include aminolevulinic acid, phenolsulfonamide and other hemostatic drugs, as well as ferrous sulfate, ferrous succinate, etc.; 2, allergy: such as allergy caused by allergic purpura, the body has a metamorphic reaction to certain allergens, capillary permeability increases, resulting in skin bleeding. It is recommended to keep away from allergens in time, and follow medical advice through medication, commonly used drugs including ibuprofen, dexamethasone, cyclosporine, cetirizine, loratadine, etc.; 3, drug factors: long-term use of glucocorticoids, aspirin and anticoagulant drugs can lead to blood coagulation dysfunction, resulting in spontaneous bleeding throughout the body, which can be seen on the skin mucosa of girls’ legs with bruises, bruises, etc., and in severe cases Even internal bleeding can occur. The drugs should be discontinued in time and treated accordingly if necessary to avoid serious complications. In addition, patients are advised to avoid trauma in daily life, pay attention to personal hygiene and prevent infection. To strengthen life management, regular rest and rest, proper exercise, healthy diet, always observe the changes of bruises, seek medical attention in time for any abnormalities and take appropriate treatment under the guidance of the doctor.