Scratching the skin with the hand there are red marks may be sharp nails, excessive force and other physiological factors, or consider the artificial urticaria and other diseases. 1. Physiological factors: if the nails are sharp, too much force, when the hand scratching the skin, will lead to local mucous membrane congestion, manifested in scratching the skin with the hand have red marks. This kind of situation, if not accompanied by other uncomfortable symptoms, is a normal phenomenon, no need to worry. 2. Artificial urticaria: the etiology of artificial urticaria is not clear, it may be caused by the release of vasoactive mediators from mast cells due to a variety of mechanical stimulation of the skin. When the patient with sharp things, scratching or rubbing the skin, there can be a clear reddish line-like elevated masses, manifested by scratching the skin with the hand there are red marks. There are many reasons that lead to the appearance of red marks when scratching the skin, it is recommended to go to the hospital, identify the cause of the disease, and follow the doctor’s instructions to standardize the treatment.