what causes horizontal ridges in fingernails

Horizontal ridges in fingernails are usually a sign that nail growth was temporarily disrupted, often by physical trauma, significant illness, or systemic health issues like nutrient deficiencies or circulation problems.

What causes horizontal ridges in fingernails?

Horizontal ridges are often called Beau’s lines , and they form when something briefly interferes with the nail matrix (the part under the cuticle that makes new nail). Because nails grow slowly, the ridge is like a “timestamp” of when your body or nail was under stress.

1. Local nail trauma and cosmetic damage

These are among the most common and more harmless causes.

• Slamming a finger in a door or dropping something heavy on it.
• Repeated pressure or friction (e.g., sports, typing, instruments).
• Aggressive manicures that push or cut the cuticle too hard.
• Long-term use of artificial/acrylic nails or gel manicures that stress or damage the nail matrix.

In these cases, the ridge often appears on the injured nail only and slowly grows out as the nail grows.

2. Severe illness or high-fever infections

A strong systemic illness can temporarily slow or stop nail production, leaving a groove that appears weeks later.

Common triggers include:

• Pneumonia or other serious lung infections.

• Measles or other high-fever viral illnesses.

• COVID‑19 and other significant systemic infections.

• Hospitalization, major surgery, or intensive care stays.

If you see similar ridges on multiple nails that line up, it often reflects a body‑wide stress episode that occurred at the same time.

3. Nutritional deficiencies

Lack of key nutrients may weaken nail formation and contribute to horizontal ridging.

• Protein deficiency can impair normal keratin production and lead to visible grooves.

• Zinc deficiency is linked with Beau’s lines and other nail changes like hair loss and delayed wound healing.

• Iron deficiency can thin the nails and cause various ridges and shape changes.

• B‑vitamin (especially biotin) deficiency can make nails more brittle and prone to surface irregularities.

These usually come with other symptoms such as fatigue, hair changes, or skin issues, not just nail ridges alone.

4. Inflammatory skin and autoimmune conditions

Chronic skin diseases that affect the nail matrix can disrupt growth and cause horizontal lines.

• Eczema (atopic dermatitis) around the fingers can inflame the nail matrix and lead to ridges, pitting, or nail shape changes.

• Psoriasis can affect nails with pitting, thickening, discoloration, and sometimes horizontal grooves.

• Other inflammatory conditions near the nail can similarly interfere with the matrix.

These conditions often show additional signs like rashes, scaling skin, or itchiness.

5. Circulation and systemic diseases

Diseases affecting blood flow or overall organ function can show up as horizontal nail changes.

• Peripheral vascular disease / peripheral artery disease (reduced blood flow to hands and feet) can impair nail growth and cause ridges.

• Diabetes can damage blood vessels and tissues in the fingers, contributing to indentations and horizontal ridges.

• Thyroid disorders (especially hypothyroidism) can slow nail growth and alter nail structure, sometimes contributing to ridging.

• Chronic kidney disease has been linked with multiple nail changes, including horizontal lines or banding.

When the cause is systemic, changes often appear across several or all nails.

6. Stress and emotional strain

Periods of intense emotional or physical stress can act like an “illness” for the body and temporarily shift resources away from nail growth.

• Extreme emotional stress or anxiety has been associated with Beau’s lines.

• Major life events (bereavement, severe burnout, trauma recovery) can sometimes coincide with the timing of new ridges.

This is usually diagnosed after ruling out more concrete medical causes and by matching the timing with stress events.

7. Medications and treatments

Some medical treatments can interrupt nail growth.

• Chemotherapy is a well‑known cause of Beau’s lines because it targets rapidly dividing cells, including those in the nail matrix.

• Other intensive systemic drugs can occasionally cause similar effects, usually noted and monitored by your care team.

After treatment ends, new nail growth typically returns to normal, and the ridges move out with time.

When should you worry?

Horizontal ridges can be harmless, but some patterns deserve prompt medical attention.

Consider seeing a doctor or dermatologist if:

• Multiple nails develop horizontal ridges all at once without clear trauma.

• Ridges are accompanied by color changes, nail lifting, pain, swelling, or pus.

• You also notice symptoms like unexplained weight change, extreme fatigue, shortness of breath, leg pain when walking, or new rashes.

• You recently had a serious illness or started major medication and want to confirm the nails are reacting normally.

A clinician can take a history, examine your nails and skin, and, if needed, run lab tests to check for deficiencies, thyroid issues, diabetes, or other conditions.

Simple care tips (while you get it checked)

These steps do not replace medical evaluation but can support healthier nails.

• Keep nails trimmed and filed smooth to avoid catching on fabrics.

• Moisturize hands and cuticles regularly to protect the nail matrix.

• Avoid aggressive cuticle cutting or pushing during manicures.

• Limit harsh removers and long‑term acrylic/gel use if your nails are already damaged.

• Aim for a balanced diet with adequate protein, iron, zinc, and B‑vitamins, ideally guided by a healthcare professional if you suspect deficiency.

Information gathered from public forums or data available on the internet and portrayed here.