Striped nails can have various causes, ranging from harmless cosmetic issues to underlying health conditions. Here are some possible reasons: Natural and Harmless Causes: Aging: Vertical ridges (onychorrhexis) are common as you get older. Injury or Trauma: A past hit to the nail can cause temporary discoloration or ridges. Nutritional Deficiencies: Lack of vitamins like biotin, zinc, or iron can contribute. Medical Conditions: Beau’s Lines: Horizontal ridges can result from illness, high fever, or malnutrition. Melanonychia: Dark stripes, especially if they appear suddenly, may require medical evaluation. Fungal Infections: Can cause white, yellow, or dark streaks. Autoimmune Disorders: Conditions like psoriasis can lead to nail ridges or discoloration. When to See a Doctor: Dark stripes that weren’t there before. Deep horizontal grooves. Changes accompanied by nail pain, brittleness, or peeling