Some patients develop skin petechiae, which may be caused by trauma. Some patients may develop subcutaneous petechiae when the local skin capillaries rupture and bleed during trauma. Some patients have fragile capillaries due to their personal constitution, and petechiae may easily appear after a slight bump. In some patients, allergies caused by exposure to allergens lead to increased vascular permeability, and patients are more likely to develop subcutaneous petechiae. In addition, oral antiplatelet drugs, such as aspirin or clopidogrel hydrogen sulfate, may cause platelet abnormalities, which may lead to subcutaneous petechiae. Patients on anticoagulation therapy with drugs such as warfarin or heparin are also prone to subcutaneous petechiae. Therefore, further examination should be conducted to clarify the cause of this condition. For example, if the skin petechiae are caused by trauma, hot compresses can be applied to promote blood circulation and eliminate the petechiae. If petechiae appear with anticoagulant drugs, further examination should be conducted to adjust the medication according to the examination results.