The common causes of vertical finger nail lines include physiological factors, physical factors, disease factors, malnutrition and so on. 1. Physiological factors: children and the elderly may have structural changes in their nails, and the appearance of vertical nail lines is a physiological phenomenon. 2. Physical factors: External stimuli such as bumps, bruises, or long-term use of nail polish may damage the nail plate, leading to the occurrence of vertical nail lines. 3. Disease factors: Certain diseases such as lichen planus, psoriasis, lupus erythematosus, etc. may cause abnormalities in the growth process of nails, resulting in the appearance of vertical lines on the nails. 4. Malnutrition: Certain patients with chronic diseases, due to long-term absorption disorders resulting in malnutrition, may also cause vertical lines on the nails. Fingernails long vertical lines may also be caused by other reasons, it is recommended that patients go to the hospital in a timely manner, after a clear diagnosis under the guidance of the doctor standardized treatment.