What causes ridges in nails

Vertical versus horizontal ridges

Nail ridges come in vertical (running from cuticle to tip) or horizontal (running across the nail) varieties. The two have very different meanings.

Vertical ridges

Lines running lengthwise from the cuticle to the tip of the nail. These are extremely common, particularly with age. Most healthy adults over 40 have some vertical ridging. Usually harmless and not associated with any specific health issue. The most common type of nail ridge by far.

Horizontal ridges (Beau lines)

Lines running across the nail from side to side. Called Beau lines after the doctor who first described them. Less common than vertical ridges and more often clinically significant. Indicate a temporary disruption to nail growth at the time the line was forming. Worth investigating particularly if multiple are present.

The direction matters

Always note the direction of nail ridges when assessing them. Vertical lengthwise ridges are usually harmless. Horizontal cross ridges warrant more attention. The direction alone tells you whether to be concerned or not in most cases. Multiple ridges of either type may also matter.

Single versus multiple nails

Ridges affecting one nail usually indicate something specific to that nail (injury, infection, local issue). Ridges affecting all nails usually indicate something systemic (health condition, illness, medication effect). The pattern of which nails are affected provides diagnostic information.

Why vertical ridges form

Vertical nail ridges have specific common causes. Knowing them helps you understand what is happening.

Age related changes

The most common cause by far. As we age, nail growth becomes slightly less uniform across the width of the nail. The variation produces lengthwise ridges. Most adults over 40 develop some vertical ridging. The ridging gradually increases with age. Completely normal and not concerning.

Dehydration of the nail

Dry nails show ridging more prominently than well moisturised nails. Daily moisturising can reduce the appearance of vertical ridges significantly. The ridges do not disappear but become less visible. This is the easiest intervention for users bothered by the appearance.

Mild deficiencies

Iron deficiency, vitamin B12 deficiency and other mild nutritional gaps can produce or worsen vertical ridges. The contribution is usually modest. Testing through your GP reveals actual deficiencies. Targeted supplementation based on test results produces improvement in deficient users.

Lichen planus and other skin conditions

Several skin conditions affect nails alongside skin. Lichen planus, eczema affecting nail beds, psoriasis and others can produce vertical ridges. Usually accompanied by other skin or nail changes. Worth mentioning to your GP if you have known skin conditions or if other unusual nail changes appear alongside ridges.

Why Beau lines form

Beau lines (horizontal ridges) indicate temporary disruption of nail growth. The disruption has specific causes worth knowing.

Recent illness

Serious illness disrupts nail growth temporarily. The disruption appears as a horizontal ridge several weeks to months later as the affected section grows out. Cold and flu typically do not produce visible Beau lines. Significant illness (pneumonia, surgery, severe infection) can produce noticeable lines.

Trauma and injury

Direct injury to the cuticle or nail matrix can produce a horizontal ridge as the nail grows. Manicure damage, hitting the finger, surgical procedures near the nail all can cause this. Usually only affects the single injured nail. Grows out over the months needed for nail replacement.

Severe stress

Significant psychological stress occasionally produces Beau lines through hormonal effects on nail growth. The stress must usually be quite severe and sustained. Mild everyday stress does not typically produce visible lines. Mentioning recent major stressors to your GP if asking about ridges helps with diagnosis.

Medication effects

Chemotherapy and some other medications disrupt nail growth and produce Beau lines. The lines correspond to treatment cycles. Other medications less commonly cause this. Mentioning current medications when discussing nail ridges with your GP matters for accurate diagnosis.

When ridges warrant attention

Several situations make medical assessment of nail ridges important.

Sudden appearance of horizontal ridges

New Beau lines without obvious explanation warrant GP consultation. The line indicates something disrupted nail growth recently. Sometimes that something is an undiagnosed illness or condition worth investigating. Speak to your GP about new unexplained Beau lines particularly if affecting multiple nails.

Ridges with other concerning changes

Ridges combined with discolouration, brittleness, pain, separation from nail bed or other significant changes warrant medical assessment. The combination often indicates more serious issues than ridges alone. Speak to your GP if multiple nail changes are present.

Pitted nails

Small depressions or pits in nail surface alongside ridges can indicate psoriasis or other inflammatory conditions. Worth a GP appointment for assessment. Treatment of underlying conditions often improves nail appearance. The pattern matters for diagnosis.

Severe ridging affecting function

Ridges severe enough to affect nail function (prevent normal use of hands, cause significant cosmetic distress) warrant medical advice. Sometimes treatments exist. Sometimes underlying conditions need addressing. The GP can advise on whether specialist referral makes sense.

More nails reading

For strength, our How to Strengthen Nails covers nail care. What Do the White Dots on Nails Mean covers another common nail change. And Why Is My Toenail Yellow covers discolouration.