Patient: The first onset was 4 years ago when many blood spots like red ants appeared on the feet, within the skin, without pain or itching. At that time, I went to a random clinic and took some medicine and it disappeared. Some time later, there were again, and then to a Chinese doctor, who said it was caused by blood heat, but it was still there after taking the medicine, only lighter in color. Then it was left alone, and the color became darker and larger. I have done a blood test and there is nothing wrong with it, I want the doctor to help me confirm what is the disease and what causes it? Liu Jiajun, Department of Hematology, The Third Affiliated Hospital of Sun Yat-sen University: According to your information, the blood routine (platelets) is normal, and small bleeding spots appear repeatedly on both lower extremities, you should consider whether you have allergic purpura (simple type or skin type). Allergic purpura is a bleeding disorder caused by allergic reaction. There are many allergens that cause this disease, such as food (fresh seafood such as shrimp, crab and egg, etc.), infectious factors (such as various bacteria and viruses, etc.), and drug factors (such as many antibiotic classes, sodium salicylate, etc.). In addition, some plant pollen or dust, etc. can also be caused, and the bite of certain insects in summer is also a common cause. I don’t know if you have any of the above mentioned causes. The treatment of allergic purpura is firstly to avoid contact with allergens, then use anti-allergic drugs such as Benadryl, paracetamol, keratan, etc., and if necessary, use a small amount of hormone treatment. In addition, there is another kind of simple purpura of unknown cause, this purpura mainly occurs in women of childbearing age, the specific cause is unknown, it may also have some relationship with endocrine changes, often in the absence of obvious triggers, small bleeding spots on the lower limbs and feet, ankles and other parts, most of them are symmetrical on both sides, but also can appear petechiae, this purpura does not need treatment, it can get better on its own and has no effect on the general health. You may also belong to this kind of purpura. In addition, we suggest you to review the blood routine, urine routine, liver function and coagulation function to rule out other causes. You can take some medications to improve the fragility of blood vessels such as vitamin C.