Toenail ridges are among the most common nail changes patients ask podiatrists about. They can be completely normal — a feature of aging nail growth — or occasionally a sign of an underlying health condition. Understanding the difference between vertical and horizontal ridges is the key to knowing when to seek evaluation.

Vertical Ridges (Longitudinal Ridges)

Vertical ridges running from the base of the nail to the free edge are the most common type and are largely benign. They become more prominent with age as nail matrix cells lose their even distribution. Dry skin, dehydration, and minor nutritional deficiencies (particularly iron and B vitamins) can accentuate vertical ridges. In most people, vertical ridges require no treatment and are simply a feature of aging nails.

Exception: A single prominent vertical ridge or groove — especially one associated with a pigmented streak (brown or black line) — should be evaluated for subungual melanoma or a nail matrix nevus.

Horizontal Ridges (Beau’s Lines)

Horizontal ridges crossing the nail from side to side — called Beau’s lines — are more clinically significant. They represent a period of interrupted nail growth due to physiological or systemic stress on the nail matrix. Common causes include:

• Systemic illness — high fever, severe infection, COVID-19, or any serious illness that disrupts the nail matrix temporarily
• Surgery or major physiological stress — Beau’s lines after major surgery are well-documented
• Nutritional deficiency — severe protein or zinc deficiency
• Chemotherapy — cytotoxic medications frequently produce Beau’s lines
• Psoriasis — nail psoriasis can produce both horizontal and irregular ridging
• Poorly controlled diabetes — blood sugar fluctuations can affect nail matrix function

The position of a Beau’s line on the nail can approximately date when the growth disruption occurred — nails grow approximately 3mm per month (toenails slower than fingernails), so a Beau’s line at the midpoint of a toenail occurred roughly 6 months prior.

Other Nail Changes That May Accompany Ridges

• Koilonychia (spoon nails) — nails that curve inward rather than outward; associated with iron deficiency anemia
• Pitting — ice-pick depressions; hallmark of nail psoriasis
• Onycholysis — nail lifting from the nail bed; associated with psoriasis, thyroid disease, and fungal infection
• Clubbing — nail curvature with soft tissue enlargement; associated with pulmonary and cardiac conditions

When to See a Podiatrist

Nail evaluation is recommended when: ridges are new and rapidly developing, a single longitudinal pigmented streak is present, ridges are accompanied by nail color changes (white, brown, or black), the nail is separating from the nail bed, multiple nails show similar changes simultaneously (suggesting systemic cause), or ridging is accompanied by pitting suggesting psoriasis.

Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.