Empty half of the thumbnail may be caused by chemical stimulation, trauma or nail fungus disease. 1. Chemical stimulation: If you are often in contact with laundry detergent, soap and other alkaline substances, due to prolonged exposure of the nails to chemical stimulation, it is easy to lead to the nail plate and the nail bed separation, resulting in the phenomenon of the big toe thumb nail is empty half of the phenomenon. 2. Trauma: if you are not careful to make the thumb trauma, resulting in separation of the nail bed and nail plate, may also appear thumb nail empty half of the situation, usually accompanied by severe pain and bleeding and other phenomena. 3. Nail fungus disease: nail fungus disease is usually caused by fungi invading the nail plate, the main symptom is the thickening of the nail bed, separation and discoloration, etc., may appear thumb nail empty half of the phenomenon. Thumbnail empty half recommended to actively go to the regular hospital, clear specific causes, and then targeted treatment.