Ridges on your nails are almost always vertical lines running from the base of the nail to the tip, and they’re a normal part of aging. Think of them like wrinkles for your nails. They become more noticeable over time as the nail matrix (the tissue under your cuticle that produces the nail) gradually changes how it lays down new cells. Most adults over 40 have some degree of vertical ridging, and it’s rarely a sign of anything wrong.
That said, not all nail ridges are the same. Horizontal ridges, changes in nail color, or ridges paired with crumbling or pitting can point to something worth paying attention to. Here’s how to tell the difference.
Vertical Ridges and Aging
Vertical ridges run lengthwise from cuticle to tip. They’re the most common type, and in the vast majority of cases, they’re simply a feature of getting older. As you age, your body produces new nail cells less evenly, and the nail plate loses some of its moisture and smoothness. The result is fine lines that run parallel down the nail surface. You might notice them first on your thumbnails or index fingers, where they tend to be most visible.
These ridges are cosmetic. They don’t indicate disease, vitamin deficiency, or organ problems on their own. If your nails are otherwise strong, normally colored, and not painful, vertical ridging is just your nails doing what nails do over time.
When Iron or Zinc Is Low
Nutritional deficiencies can sometimes cause or worsen nail ridges. Iron deficiency is linked to vertical ridging and, in more severe cases, a condition called koilonychia, where the nail develops a spoon-shaped dip in the center deep enough to hold a drop of water. Zinc deficiency, on the other hand, tends to cause horizontal ridges and white spots on the nails.
If your ridges appeared relatively suddenly, you’ve noticed your nails becoming unusually brittle, or you have other signs of low iron (fatigue, pale skin, shortness of breath), a blood test can clarify whether a deficiency is involved. For most people with mild vertical ridges, though, nutrition isn’t the issue.
Horizontal Ridges Are Different
Horizontal ridges, called Beau’s lines, run side to side across the nail. They look like indentations or grooves, and they form when something interrupts nail growth temporarily. Unlike vertical ridges, Beau’s lines almost always have a cause worth identifying.
The list of triggers is long. Illnesses with high fever (pneumonia, strep infections, COVID-19) are common culprits. So are heart attacks, measles, and mumps. Chronic conditions that reduce blood flow to the nail matrix, including diabetes, hypothyroidism, peripheral artery disease, and Raynaud’s phenomenon, can also produce them. Even severe emotional stress from a major life event like a divorce or death in the family has been linked to Beau’s lines.
Skin conditions like psoriasis and eczema can trigger them too, along with severe zinc deficiency or insufficient protein intake. Direct trauma to the nail, such as slamming your finger in a door, dropping something heavy on it, or exposure to extreme cold, is another possibility.
How to Estimate When the Disruption Happened
Fingernails grow about 3.5 millimeters per month, or roughly a tenth of a millimeter per day. Toenails grow at about a third of that rate. Because Beau’s lines form at the base of the nail and move forward as the nail grows, you can estimate when the interruption occurred by measuring the distance from the line to your cuticle. A groove sitting about 7 millimeters from the cuticle, for example, suggests something happened roughly two months ago.
If the same groove appears at the same position across most or all of your nails, that points to a systemic event (an illness, high fever, or major stressor) rather than local trauma to one finger.
Ridges From Skin Conditions
Nail psoriasis produces changes that go well beyond simple ridging. You might notice small dents or pits in the nail surface, ranging from pin-tip size (about 0.4 millimeters) to crayon-tip size (about 2 millimeters). Some people develop just one or two pits per nail, while others have ten or more. The nail bed can also discolor, turning yellow, red, pink, or brown in patches sometimes called oil drop spots.
In more advanced cases, psoriasis can thin the nail until it crumbles, or cause the thick skin under the nail tip to separate from the nail bed entirely, which then opens the door to fungal infections. Eczema affecting the fingers can cause similar, though typically milder, changes to nail texture.
If your nail ridges come with pitting, discoloration, or crumbling, a skin condition is a more likely explanation than aging alone.
Ridges From Picking or Rubbing
A specific pattern of ridging called habit-tic deformity comes from repeatedly picking at, pushing back, or rubbing the cuticle area, often unconsciously. This typically affects the thumbnails and creates a distinctive “washboard” look: a central depression running down the middle of the nail with short, parallel horizontal ridges running across it. You’ll also usually notice partial cuticle loss and thickened skin along the nail fold.
Because the habit is often unconscious, many people don’t connect their nail changes to something they’re doing with their own hands. If you see this washboard pattern primarily on your thumbnails, pay attention to whether you’re fidgeting with that area during the day.
Roughness Across All Nails
A less common condition called trachyonychia, sometimes nicknamed “twenty-nail dystrophy,” causes excessive longitudinal ridging across most or all nails. The nails develop a rough, sandpaper-like texture with fine parallel striations running lengthwise. Cuticles often become ragged and thickened. It comes in two forms: an opaque version where nails lose their shine completely, and a shiny version where nails look opalescent but still feel rough and ridged. Trachyonychia is most often seen in children and is sometimes associated with underlying conditions like alopecia areata or lichen planus.
What You Can Do About Ridges
For normal vertical ridges, your options are cosmetic. Ridge-filling base coats contain ingredients like biotin and botanical oils that fill in the grooves to create a smoother surface for nail polish or just a more even appearance on bare nails. They work like a primer, not a treatment. The ridges are still there underneath.
Gentle buffing can temporarily smooth the nail surface, but it physically removes layers of the nail plate. Doing this too often or too aggressively thins the nail over time, so it’s best used sparingly.
You may have heard that biotin supplements strengthen nails and reduce ridging. The evidence for this is weak. The American Academy of Dermatology has cautioned against using biotin supplementation as a primary treatment for nail regrowth or repair, noting that only one clinical trial has been conducted, with a small sample size and results based largely on participants’ own perceptions rather than objective measurements. Biotin may help if you have a confirmed deficiency, but most people don’t.
For horizontal ridges, the ridge itself will grow out on its own as the nail advances. At typical growth rates, a fingernail takes about four to six months to fully replace itself. The more important step is identifying what caused the growth interruption in the first place, especially if the lines keep recurring or appear on multiple nails at once.
Keeping nails moisturized, avoiding harsh chemicals without gloves, and leaving cuticles intact rather than cutting them aggressively all help maintain the smoothest nail surface your biology will allow. But some degree of ridging, especially the vertical kind, is simply part of having human nails that have been growing for a few decades.