1. Age As we get older, keratin (the protein in nails) is laid down less evenly. Result? Subtle vertical grooves. It’s the same process that puts wrinkles on your face—perfectly normal.
  2. Dehydration Nails are porous. When you’re chronically dry (winter air, too much hand-washing, acetone polish remover), ridges pop out like dry, cracked soil. Fix: drink more water and slather on hand cream and cuticle oil religiously.
  3. Everyday micro-trauma Typing, picking cuticles, bumping your nails—these tiny insults can leave faint vertical lines as the nail grows out.
  4. Mild nutrient dips (rarely the only cause) Low iron, B12, or magnesium can contribute, but you’d almost certainly have fatigue, hair loss, or other louder symptoms too. Vertical ridges by themselves almost never mean serious deficiency.

Bottom line: vertical ridges are usually just life happening to your nails.

When Horizontal Ridges (Beau’s Lines) Are a Red Flag

A deep horizontal groove means the nail matrix—the factory under your cuticle—temporarily shut down or slowed dramatically. Because nails grow only 2–3 mm per month, that line shows up weeks or months after the triggering event.

Common causes of this “growth pause”: