Vertical ridges are a normal age change. Horizontal dents mark a past illness; spoon nails suggest iron deficiency; a single dark streak down one nail should be checked promptly.
What to do
Common questions
What does it mean if my nails have ridges?
Ridge direction is the whole answer. Vertical ridges running from cuticle to tip are a normal aging change - MedlinePlus notes nails commonly develop these lines over time, like wrinkles for nails. If every nail has had fine vertical lines for years, that is you, not a disease. Dryness and frequent wet work make them more visible, and moisturizer plus gloves actually helps. Horizontal dents are different. A groove running across the nail - Beau lines - means the nail factory paused during a period of high fever, major illness, surgery, or severe stress, and the groove grows out over months. You can roughly date the event: nails grow about three millimeters a month, so a dent near the cuticle is recent. Spoon-shaped nails that curve upward - koilonychia - are the classic sign of iron deficiency and deserve a blood test. Pitting, thickening, or crumbling points toward psoriasis or fungus. One nail warning to know: a single dark streak down one nail, especially if widening or reaching the cuticle, should be looked at promptly - that pattern occasionally marks a nail-bed melanoma and is the one nail change not to watch for months. Pymander is a free AI doctor, 24/7 by text. Describe the ridges - direction, one nail or all - and it can help you read them.