The causes of ingrowns may be related to the lack of certain nutrients or stimulation by external factors. 1. Lack of nutrients, a period of time intake of vitamins or other trace elements is not enough to support the normal use of the body, and there is a significant lack of state, will lead to the skin has no luster, the surface of the skin will become rough and gradually aging, the surface of the skin will also be dry and yellowish, which will lead to the local skin on the skin of the appearance of abnormal skin barbs. 2. External factors stimulation, frequent contact with irritating, weak corrosive chemicals, or frequent contact with the surface of the rough surface or the surface of the unclean goods, will have a stimulation of the surface of the skin, the skin is no longer as smooth as it used to be, the skin will appear on the barbs. The formation of barbs does not exclude other causes, it is recommended that the patient timely to the hospital, under the guidance of the doctor to choose the appropriate treatment.