Ridges in fingernails are almost always caused by normal aging, but their direction matters. Vertical ridges running from cuticle to tip are extremely common and rarely signal a health problem. Horizontal ridges running side to side are more likely tied to illness, injury, or nutritional deficiency. Understanding which type you have is the first step to figuring out whether your ridges need attention or are simply part of getting older.
Vertical Ridges and Aging
Vertical ridges are the most common nail surface change in adults, showing up in roughly 85% of older people. They run lengthwise from the base of your nail to the tip and become more pronounced with each decade. If you run your finger across a ridged nail and feel fine lines going up and down, this is what you’re looking at.
These ridges form because the nail matrix, the hidden tissue under your cuticle that produces the nail plate, changes as you age. The cells that build your nail grow larger and less uniform over time. The blood vessels and elastic tissue beneath the nail bed also thicken, which alters how smoothly the nail grows out. Think of it like tree bark developing deeper grooves over the years. The nail plate itself can become more brittle and prone to splitting along those ridges, a combination sometimes called onychorrhexis.
Vertical ridges from aging are harmless. They don’t indicate a vitamin deficiency or hidden disease. They’re the nail equivalent of wrinkles.
Horizontal Ridges: A Different Story
Horizontal ridges, called Beau’s lines, are indentations that run across the nail from side to side. Unlike vertical ridges, these form when something temporarily disrupts nail growth. The nail matrix essentially pauses or slows production, leaving a dent that moves forward as the nail grows out.
The most common causes identified in clinical research break down this way: medications (particularly chemotherapy drugs) account for roughly 36% of cases, followed by systemic illnesses like uncontrolled diabetes or vascular disease at about 25%, physical trauma at 12.5%, and infections at about 7.5%. Autoimmune diseases, neurological conditions, and hereditary disorders make up the remainder.
Here’s a useful trick: fingernails grow at an average rate of about 3.5 millimeters per month. If you spot a horizontal ridge, you can roughly estimate when the disruption happened by measuring how far the ridge is from your cuticle. A ridge sitting 7 millimeters from the base likely formed about two months ago, which might line up with a high fever, surgery, or a period of severe stress.
A single horizontal ridge on one nail usually points to local trauma. If the same ridge appears across multiple nails at the same position, that suggests something systemic affected your whole body at once.
Skin Conditions That Affect Nails
Psoriasis is one of the most significant causes of nail ridging and texture changes. Nail psoriasis can produce horizontal grooves (Beau’s lines), pitting that looks like tiny dents made by a pin tip, and structural thinning that makes nails crumble. The pits range from about 0.4 millimeters to 2 millimeters across, and a single nail might have anywhere from one or two to more than ten. Discoloration beneath the nail, appearing as yellow, red, or brown patches, often accompanies these texture changes.
A condition called trachyonychia produces nails that look and feel like they’ve been rubbed with sandpaper. The nails develop rough, excessive longitudinal ridging and lose their normal shine. In its more severe form, the surface becomes opaque and gritty. In milder cases, nails appear opalescent with scattered pits. Trachyonychia can appear on its own without any clear cause, but it’s most frequently linked to alopecia areata (a hair-loss condition), psoriasis, and lichen planus.
Nutritional Deficiencies
Iron deficiency anemia can cause a distinctive nail change called koilonychia, where nails develop raised ridges, thin out, and curve inward like a spoon. If your nails look concave enough to hold a drop of water, iron deficiency is a likely culprit. This is one of the few nutritional causes that produces a recognizable pattern.
Zinc deficiency can cause horizontal Beau’s lines along with white spots on the nails. Severe protein deficiency can produce similar horizontal disruptions, since your body needs adequate protein to build the keratin that forms the nail plate. These deficiencies are more common in people with absorption issues or very restrictive diets than in the general population. If a deficiency is confirmed through blood work, supplementation with iron or zinc typically allows healthy nail growth to resume, though it takes several months for the affected portion to grow out completely.
Physical Trauma and Habits
Damage to the nail matrix leaves a lasting imprint on every bit of nail it produces until the injury heals. Longitudinal ridges from trauma form when scar tissue builds up in or beneath the matrix, and the nail conforms to the shape of the scarred tissue underneath. A single vertical ridge that appears on one nail and doesn’t match the others is a classic sign of prior injury to that finger.
Subtler habits cause problems too. Picking at cuticles, biting nails, or prying the skin fold at the base of the nail can damage the matrix enough to distort nail growth. The good news is that once you stop the habit, the nail shape usually restores itself over time. Transverse ridges can also form during regrowth after trauma or periods of reduced blood flow to the fingers.
Excessive exposure to water and harsh chemicals, including cleaning products, certain hand soaps, and hand sanitizers, can worsen existing ridges and weaken the nail plate.
Improving Ridged Nails at Home
For cosmetic vertical ridges, gentle buffing can smooth the surface, but limit it to once a month. Over-buffing thins the nail plate and can make things worse. Use a four-way nail file, move in one direction only, and apply light pressure. Many buffers sold at beauty supply stores are designed for acrylic nails and are far too abrasive for natural nails.
Keeping nails moisturized helps prevent ridges from catching and splitting. Applying nail oil, vitamin E oil, coconut oil, or olive oil to your nails and cuticles regularly supports flexibility. A moisturizing hand soap and a protective hand cream reduce the drying effects of daily wear. A weekly layer of nail hardener can add some structural reinforcement.
Regular cardiovascular exercise improves blood flow to the fingers, which supports healthier nail growth from the matrix. Since the nail matrix depends on a steady blood supply to produce a smooth, even nail plate, anything that boosts circulation to your hands can help reduce ridging over time. It won’t eliminate age-related ridges entirely, but it supports the best growth your nails can achieve.