Run a fingertip over a bare nail and you will feel its texture. Fine lines from cuticle to tip appear in most people by their forties and deepen slowly with the years. A groove that crosses the nail from side to side is different: it records a week or two when the nail stopped growing, and it moves up the nail like a tide mark until it is filed away.
Both kinds are common, and both are mostly harmless. The care differs. Vertical ridges respond to oil, a light buff and a ridge-filling base coat under colour. A Beau's line cannot be buffed out and needs nothing except time, once the cause is known. A small number of ridges, in both directions, are signs that deserve a GP's opinion.
What are ridges on nails?
A nail ridge is a raised or sunken line on the nail plate that you can see or feel with a fingertip. The Cleveland Clinic describes ridges as visible lines or dents in the fingernails or toenails and groups them by direction (Cleveland Clinic). Direction is the first thing a dermatologist looks at, because vertical and horizontal ridges have different causes.
Vertical ridges run from the cuticle to the free edge, like the grain in wood. Horizontal ridges run across the nail from side to side. The medical term for lengthwise ridging is onychorrhexis. The term for a groove across the nail is a Beau's line, which DermNet defines as a transverse depression affecting all nails, due to acute systemic illness stopping nail growth (DermNet).
| Feature | Vertical ridges (onychorrhexis) | Horizontal ridges (Beau's lines) |
|---|---|---|
| Direction | Cuticle to tip | Side to side |
| Usual cause | Ageing, dry nails, eczema | Illness with fever, injury, chemotherapy, harsh manicures |
| Nails affected | Most or all, slowly over years | Often all nails at once, at the same distance from the cuticle |
| Less common causes | Underactive thyroid, iron deficiency, lichen planus | Zinc deficiency, severe malnutrition, diabetes |
| What helps | Oil, hand cream, a light buff, a ridge-filling base coat | Time; the groove grows out in about six months |
| See a doctor | If new, deep, or with colour change or brittleness | If you cannot link the line to an illness or injury |
Why do vertical ridges appear with age?
Vertical ridges are the most common nail change in adults and most of them are harmless. The Cleveland Clinic notes that many people develop vertical ridges on their nails as they get older, in the same way that skin develops fine lines. The nail matrix, the growth zone under the cuticle, produces the plate in fine columns, and with age those columns become less even.
Dryness makes ridges look deeper. A nail plate with little oil between its keratin layers reflects light unevenly, so every ridge shows. This is why ridges seem worse in winter and after weeks of remover, and why oil makes them look softer within days. The plate itself has not changed; the surface is smoother and better lit.
A few internal causes produce the same look. The Cleveland Clinic lists dry skin and eczema, an underactive thyroid (which gives thick, brittle nails with vertical ridges) and iron deficiency among the causes of vertical ridging. These usually come with other signs, such as tiredness, dry skin elsewhere or nails that snap, and a GP can test for both with one blood sample. The nail signs that point to iron or thyroid are set out in brittle nails: causes and care.
What are Beau's lines and what causes them?
A Beau's line is a groove across the nail that marks a pause in growth. When the body is under strain, the matrix slows or stops making new plate for days or weeks. When growth restarts, the thin section it left behind moves forward with the nail as a dent. The American Academy of Dermatology (AAD) lists fever, injury, chemotherapy and severe stress as the events that halt growth this way (AAD).
The NHS says deep lines or grooves in the nails may happen when you are ill but should grow out (NHS). The Cleveland Clinic adds COVID-19, measles and pneumonia to the list of illnesses with high fever that leave a line, and names two causes that come from the manicure table: gel manicures or artificial nails worn long-term, and injury to the nail (Cleveland Clinic, Beau's lines). Severe zinc deficiency and protein malnutrition are rarer causes.
Dating the line
Fingernails grow about 3 to 4 mm a month (Medscape). A line 5 mm from the cuticle was made about six weeks ago; a line halfway up the nail, about three months ago. Most people can match the position to a fever, an operation or a bad fortnight. A line on one nail alone usually means a knock to that finger. A line at the same height on all ten nails means the whole body paused, which is the pattern that follows illness.
Can you buff ridges away safely?
Yes, lightly, and only the vertical kind. A buffer removes the peaks of the ridges so light reflects evenly, and the Cleveland Clinic includes a gentle buff among the things that help. The risk is thinning. Each pass removes plate, the plate does not grow back in place, and a nail that is thinned every week ends up soft and bendy. Buffing a Beau's line is pointless because the dent is already a thin section of plate; removing more plate around it only makes the nail weaker.
You will need
- A fine buffing block, 240 grit or finer, or a glass file with a smooth side (Essie advises nothing coarser than 240 grit)
- A soft brush or cloth to wipe away dust
- Cuticle oil
- A ridge-filling base coat
Steps
- Work on clean, dry, unpolished nails. Wet plate is soft and buffs away faster than you intend.
- Hold the buffer flat and pass it across the nail in one direction, from side to side, three or four times. Stop as soon as the surface looks even.
- Skip the area near the cuticle, where the plate is thinnest and newest.
- Wipe away the dust and massage in one drop of oil per nail.
- Buff no more than once a month. Between buffs, oil and a ridge-filling base do the smoothing.
How does a ridge-filling base coat work?
A ridge-filling base coat is a base coat with fine particles, usually silica or talc, that settle into the low points of the plate and dry to a level surface. Colour applied over it looks smooth because the polish is lying on a flat film, not on the ridges. It fills; it does not remove. When the base is taken off, the ridges are still there, and nothing has been sanded away.
The trade-off is thickness. A filling base is slightly thicker than a plain base, so it needs a thin coat and a little longer to dry before colour goes on. It suits crème and metallic finishes best, because those show ridges most; sheer and jelly polishes are more forgiving and can go over a plain base. India Anaïs The Base is one example of a ridge-smoothing base with a satin finish; it is sold out and the next edition is planned for spring 2027. What a base coat does beyond filling is in what does a base coat do.
When do ridges need a doctor?
Most ridges need patience, not a prescription. The AAD advises seeing a dermatologist when nails change, swell or cause pain, and the NHS asks people to see a GP when a nail has changed shape or colour without a reason they know. For ridges specifically, the Cleveland Clinic asks patients to tell their provider about any new ridges or lines, in particular when colour changes, pitting or swelling come with them.
- Beau's lines on all nails with no illness, fever, injury or new medicine to explain them.
- Ridges together with brittleness, tiredness, hair loss or feeling cold, which points to thyroid or iron testing.
- A single ridge or groove down one nail that is new, widening or coloured. A dark streak under a nail needs a dermatologist at once.
- Pits (small dents like pin pricks) alongside ridges, a sign of nail psoriasis, eczema or alopecia according to the NHS.
- Ridges on a nail that is thickening, crumbling or lifting, which suggests fungal infection.
The full list of nail changes that need a medical opinion, and what a GP or dermatologist checks, is in nail changes: when to see a doctor.
- Vertical ridges from cuticle to tip are a normal part of ageing and look deeper when the plate is dry.
- A horizontal groove across the nail is a Beau's line, a record of a pause in growth during illness, fever or injury.
- At 3 to 4 mm of growth a month, the distance from the cuticle to a Beau's line tells you when the event happened.
- Buff vertical ridges lightly, no more than once a month, with 240 grit or finer; a ridge-filling base coat does the rest under colour.
- Ridges with pits, colour change, brittleness or no known cause deserve a GP visit.
Questions people ask
Are vertical ridges on nails a sign of a vitamin deficiency?
Usually not. Vertical ridges are most often a normal change with age and dry nails. Iron deficiency and an underactive thyroid can cause them, but they come with other signs such as brittleness, tiredness or dry skin. A GP can check both with one blood test.
How long do Beau's lines take to grow out?
About six months on fingernails, because a fingernail replaces itself in roughly that time at 3 to 4 mm a month. Toenails grow at about half that speed, so a line on a toenail takes a year or more. The line moves towards the tip and is filed away when it reaches the free edge.
Can gel manicures cause ridges in nails?
Yes. The Cleveland Clinic lists long-term gel manicures and artificial nails among the causes of Beau's lines, because rough removal and pressure injure the matrix. A break between sets and soak-off removal, never peeling, protect the plate.
Is it safe to buff ridges on nails?
A light buff with 240 grit or finer, three or four strokes in one direction, once a month, is safe on vertical ridges. Buffing more often thins the plate. Beau's lines should not be buffed at all, since the groove is already a thin section of nail.
What is the best base coat for ridged nails?
A ridge-filling base coat. It contains fine particles that settle into the ridges and dry to a level surface, so crème and metallic polishes look smooth on top. Apply one thin coat and let it dry fully before colour.