It can be difficult to determine the cause of irritated patches of skin on the face. However, cold sores and cuts do have several features that should enable most people to distinguish between the two skin problems. If you remain unsure of what has caused a lesion on your face, consult a doctor so that appropriate treatment techniques can be initiated.
Look for the indications of a cut. Cuts are caused by trauma to the skin with a sharp object. A straight or nearly straight line where the edge of the sharp object contacted the skin should be visible once bleeding has stopped. If such a line is present, it is likely that you have cut your skin and do not have a cold sore.
Check for the symptoms of a cold sore. These include a burning, itching or tingling feeling around the lips or nearby parts of your face followed by the appearance of a red rash. On top of the red rash, a fluid-filled blister will appear. According to the Mayo Clinic, this blister will break open, releasing its fluid (which may include blood). It will start to heal within about a week after it develops.
Consider the location of the wound. If it is inside your mouth, it is unlikely to be a cold sore; cold sores only rarely occur inside the mouth. If the affected area is inside your mouth, it may be a cut, canker sore or other condition. A doctor may be better equipped to examine affected areas of skin within the mouth itself.