Vertical ridges running from the cuticle to the tip often become more visible with age and, on their own, usually aren’t alarming. Nails consist mainly of keratin, a protein, and adequate nutrition supports healthy growth. Although insufficient protein or certain nutrient deficiencies can affect nails, ridges alone cannot reveal a deficiency. Regular moisturizing and protection from repeated wetting and harsh chemicals may help reduce brittleness.

Horizontal grooves deserve attention to their context: they can appear after illness, injury, or another interruption in growth, especially across several nails. Arrange a medical assessment if changes are sudden or persistent, or if you notice pain, swelling, or separation of the nail. A new or widening dark streak warrants prompt evaluation. You don’t have to solve the mystery yourself—or buy supplements on a guess. A clinician can review your symptoms, examine your nails, and determine whether targeted testing is appropriate for your particular situation.