Healthy nails are smooth, slightly curved plates with a pinkish tone that comes from the blood-rich nail bed underneath. They have subtle vertical ridges running from base to tip, a thin white arc (the free edge) you trim, and a small half-moon shape near the base called the lunula. Changes in color, texture, shape, or thickness can signal anything from minor trauma to a systemic health condition, so knowing what normal looks like helps you spot what isn’t.
Parts of a Healthy Nail
The nail plate is the hard, slightly curved surface you can see and touch. In a healthy nail, it’s mostly smooth with faint lengthwise ridges and a pinkish, semi-translucent appearance. The white tip at the end, called the free edge, is the part you clip. At the base, a thick band of skin called the cuticle seals the gap between nail and skin, acting as a barrier against germs. Beneath the free edge, a strip of skin called the hyponychium does the same job on the underside, keeping irritants and bacteria from getting trapped beneath the nail.
The lunula, that pale half-moon most visible on the thumbs, is the only part of the nail matrix you can see. The matrix itself sits hidden under the skin at the base and is responsible for producing new nail cells. Fingernails grow at roughly 3.5 mm per month, which means a full fingernail takes about four to six months to replace itself. Toenails grow at about half that rate, around 1.6 mm per month, and can take over a year to fully regrow.
Vertical Ridges vs. Horizontal Ridges
Fine vertical lines running from the base to the tip of your nail are extremely common and usually harmless. They become more noticeable with age, much like fine lines on skin. Very dry skin, eczema, thyroid problems, and iron deficiency can make them more pronounced, but on their own they rarely point to anything serious.
Horizontal ridges are a different story. Called Beau’s lines, these are dents or grooves that run side to side across the nail. They form when something temporarily interrupts nail growth: a severe illness with high fever (including COVID-19, measles, or pneumonia), a significant injury to the finger, chemotherapy, zinc deficiency, or long-term damage from acrylic or gel manicures. Because the nail keeps growing forward, you can roughly estimate when the disruption happened based on how far the line has traveled from the base.
White Spots and Color Changes
Small white spots or specks on a nail are one of the most common nail changes. In most cases they’re caused by minor injuries you may not even remember: bumping a nail, wearing tight shoes, biting your nails, or having them buffed aggressively during a manicure. The spots grow out on their own over a few months and don’t need treatment. Occasionally, white spots across many nails at once can be linked to a systemic condition like diabetes, liver disease, or psoriasis, but this is uncommon.
More dramatic color changes carry more specific meanings. Nails that look almost entirely white with a thin brown or pink band at the tip, sometimes described as frosted glass in appearance, are called Terry’s nails and are associated with liver disease. Nails that are half white on the lower portion and half brown or reddish on the upper portion are called Lindsay’s nails and are more commonly seen with kidney disease. Neither pattern is a diagnosis on its own, but both are worth bringing up with a doctor.
Shape Changes That Matter
Spoon-shaped nails are one of the more visually striking changes. The nail flattens out first, then gradually develops a concave dip deep enough to hold a small drop of water. This is strongly linked to iron deficiency and tends to develop slowly over weeks or months. Correcting the iron deficiency usually allows the nail to grow back with a normal curve.
Clubbing is the opposite problem: the fingertips enlarge and the nails curve downward, wrapping around the fingertip. A simple self-check involves pressing two matching fingernails together back to back. Normally you’ll see a small diamond-shaped gap between the nail beds. If that gap disappears, clubbing may be present. In a healthy finger, the angle where the nail meets the skin at the base is 160 degrees or less. With definitive clubbing, that angle exceeds 180 degrees, giving the fingertip a bulbous, rounded look. Clubbing is associated with heart and lung conditions that reduce oxygen levels in the blood.
Signs of Fungal Infection
Nail fungus typically starts as a white or yellowish-brown spot near the tip of a toenail, though it can affect fingernails too. As the infection moves deeper, the nail thickens, becomes discolored (yellow, brown, or greenish), and starts to crumble or develop ragged edges. Advanced infections can cause the nail to separate from the nail bed entirely, and the area often develops a noticeable odor. Toenails are affected far more often than fingernails because the warm, moist environment inside shoes encourages fungal growth.
Nail Psoriasis
If you have psoriasis, your nails may develop small dents or pits on the surface. These can be as tiny as a pinprick or as wide as a crayon tip, and you might see just one or two pits or more than ten on a single nail. Another hallmark is a discoloration beneath the nail that looks like a drop of oil trapped under the surface. These “oil drop spots” appear yellow, red, pink, or brown and are one of the more distinctive signs that nail changes are psoriasis-related rather than caused by something else.
Dark Lines and Splinter Hemorrhages
Thin, reddish-brown lines running lengthwise under the nail look exactly like tiny splinters and are called splinter hemorrhages. A single one after bumping your hand is nothing to worry about. Multiple splinter hemorrhages across several nails, especially without any injury, can be a sign of endocarditis (an infection of the heart valves) or inflammation of blood vessels. They tend to appear in the later stages of endocarditis rather than as an early warning sign.
A brown or black band of pigment running from the base of the nail to the tip deserves closer attention. While pigmented nail bands are common and benign in people with darker skin tones, certain features raise concern for melanoma under the nail. A band that is 3 mm or wider, has uneven or blurry borders, changes in width or color over time, or extends pigment onto the surrounding skin (called Hutchinson’s sign) warrants prompt evaluation. This type of melanoma is disproportionately common in Black, Asian, and Native American populations, where it accounts for up to one third of all melanoma cases.
How Nails Change With Age
As you move into your 60s and 70s, nails naturally shift from semi-translucent and pinkish to more yellowed and opaque. Growth slows, and nails become duller, more brittle, and more prone to splitting. Toenails in particular tend to thicken and harden, making them more difficult to trim and more likely to become ingrown. These changes are a normal part of aging, but they can overlap with and mask signs of fungal infections or other conditions, so new changes in a nail that’s already thick and yellow are still worth paying attention to.