A divot in your nail is almost always caused by a temporary disruption to the nail matrix, the hidden tissue beneath your cuticle that produces new nail cells. When something interrupts that production, whether illness, injury, or a skin condition, the nail grows out with a visible dent or groove. Most of the time, the divot grows out on its own and your nail returns to normal.
The type of divot matters. A horizontal groove running side to side across the nail suggests a different cause than a cluster of tiny pinpoint dents or a single central channel running lengthwise. Identifying which pattern you have helps narrow down what happened.
Horizontal Grooves (Beau’s Lines)
The most common type of nail divot is a horizontal depression that runs across the width of your nail, known clinically as a Beau’s line. These form when nail growth temporarily pauses or slows, leaving a visible groove in the nail plate as it grows out. Think of it like a tree ring marking a stressful season.
A wide range of triggers can cause these grooves. A large systematic review found that medications (particularly chemotherapy drugs) were the single most common cause, followed by systemic illnesses like high fevers and severe infections. Trauma to the nail itself accounted for about 12.5% of cases. Eczema around the nail, poor nutrition, and major surgery are also well-documented triggers.
You can actually estimate when the disruption happened by measuring where the groove sits on your nail. Fingernails grow at an average rate of about 3.5 mm per month. If the groove is roughly 7 mm from your cuticle, the interruption likely occurred about two months ago. This is especially useful if you’re trying to connect the divot to a specific illness or stressful event.
COVID-19 and Post-Viral Grooves
Since 2020, many people have noticed horizontal grooves appearing one to four months after a COVID-19 infection. This timing lines up perfectly with how long it takes for a newly disrupted section of nail to grow past the cuticle and become visible. The grooves are more common after severe infections, and some clinicians now consider them a marker of a strong immune response. Any significant viral illness, not just COVID, can produce the same effect.
Tiny Pits Across the Nail Surface
If your divots look less like a groove and more like a scattering of tiny pinhead-sized dents (typically under 1 mm across), you’re likely looking at nail pitting. This pattern points toward different causes than Beau’s lines.
Psoriasis is the condition most strongly linked to nail pitting. In one study, 37% of people with psoriasis had visible nail pits, compared to about 10% of people without the condition. The number of pits matters diagnostically: fewer than 20 pits spread across all your nails can be a normal finding, but more than 60 pits strongly suggests psoriasis, even if you don’t have obvious skin plaques yet. The pitting also tends to worsen as psoriasis becomes more severe and as the disease duration increases.
Alopecia areata, an autoimmune condition that causes patchy hair loss, produces a similar but finer pitting pattern. If you’re noticing small nail dents alongside thinning hair or bald patches, this connection is worth mentioning to your doctor.
A Central Groove Down the Middle
A lengthwise channel running from your cuticle to the tip of your nail, often on one or both thumbnails, has a surprisingly common cause: unconscious picking or rubbing at your cuticles. This is called habit-tic deformity. Most people who have it don’t even realize they’re doing it. The repetitive trauma to the cuticle area damages the nail matrix underneath, producing a central depression flanked by horizontal parallel ridges that look almost like a washboard.
Thumbnails are the most frequent targets because people typically push at one thumbnail’s cuticle with the index finger of the same hand. Once you become aware of the habit and stop, the nail grows out normally within a few months.
Nutritional Deficiencies
Poor nutrition can slow or disrupt nail growth enough to create visible depressions. Iron deficiency, zinc deficiency, and generally inadequate calorie intake are the most commonly cited nutritional causes. Unlike the dramatic grooves of Beau’s lines, nutritional nail changes tend to develop gradually and may appear on multiple nails at once. If your diet has been significantly restricted or you’ve had absorption issues (from gastrointestinal problems or weight-loss surgery, for example), this is worth considering.
Will the Divot Go Away?
In most cases, yes. Minor damage to the nail matrix is temporary. Once the underlying trigger resolves, whether that’s recovering from an illness, stopping a medication, or breaking a picking habit, healthy nail tissue starts forming again. The divot simply grows out as new nail replaces it, which takes about four to six months for fingernails to fully cycle through.
Permanent nail changes are rare. They typically only happen when the nail matrix itself is severely or repeatedly damaged, such as from a crushing injury, chronic infection, or prolonged inflammatory disease that scars the tissue. Even then, it’s the exception rather than the rule.
Signs That Need Attention
A single groove on one nail after a known injury or illness is rarely concerning. But certain nail changes signal something more serious. Dark pigmented streaks or bands in the nail bed, nails that separate from the underlying skin with discoloration, and clubbing (where the fingertips swell and the nails curve dramatically downward) can all point to conditions affecting the liver, lungs, or heart. Nails that turn mostly white with only a narrow pink band at the tip have been associated with liver disease, heart failure, and diabetes.
Multiple Beau’s lines appearing across all your nails at the same level suggest a systemic event rather than local trauma. If you can’t connect the timing to an illness you already know about, or if new grooves keep forming, that pattern is worth investigating with a healthcare provider.