Nails with white lines are usually caused by normal physiological phenomena, micronutrient deficiencies, iron-deficiency anemia, and nail injuries. Normal physiological phenomenon: due to individual differences, there will be white lines on the nails. Micronutrient deficiencies: due to picky eating or partiality, the body lacks certain micronutrients, such as zinc deficiency, calcium deficiency, and so on, so there are white lines on the nails. Iron deficiency anemia: Anemia is caused by the depletion of iron stored in the body, resulting in the reduction of red blood cells in the body. Patients may have symptoms such as pale face, generalized weakness, and white lines on the nails. Nail injury: due to trauma to the nails, there will be localized pain and swelling, and without full recovery, there will be white lines on the nail area. When there are white lines on the nails and accompanied by other symptoms, it is recommended to go to the hospital in time for examination and follow the doctor’s instructions for treatment.