Beau’s lines are transverse, white, linear depressions on the fingernails that indicate temporary interruption of nail growth. They commonly appear following severe systemic illness, toxic reactions, or physiological stress. The lines are generally bilateral and symmetric, but may vary depending on the severity and timing of the insult.

Pathophysiology

• Nail growth originates from the nail matrix, where keratinocytes proliferate.

• Any acute systemic insult—such as severe infection, metabolic derangement, chemotherapy, or ischemia—can temporarily halt matrix activity, resulting in a transverse groove.

• The width of the line correlates with the duration of the growth arrest, and its position indicates the time elapsed since the insult, as nails grow at approximately 0.1 mm/day for fingernails.

Examination Technique

• Patient positioning: Seated or supine with hands resting comfortably.

• Inspection:

  1. Examine all fingernails and toenails for transverse depressions.

  2. Note number, width, depth, and color of lines.

  3. Check for associated nail changes, such as discoloration, pitting, or onycholysis.

• Assessment:

  • Presence of well-defined transverse grooves constitutes a positive finding.

  • Correlate with patient history to identify possible triggering events.

Clinical utility

• Indicator of systemic stress: Beau’s lines reflect a recent period of severe illness, high fever, or toxic exposure.

• Chronological marker: The location of the lines can help estimate the timing of the insult based on nail growth rates.

• Adjunct in diagnosis: Useful in malnutrition, coronary events, chemotherapy monitoring, and trauma evaluation.

Differential Diagnosis

Management

• Identify and address underlying cause: Treat systemic illness, correct nutritional deficiencies, or modify toxic exposures.

• Supportive care: Nail growth usually resumes spontaneously once the underlying condition resolves.

• Patient education: Reassure patients that Beau’s lines are cosmetic and transient; normal nail appearance returns over months.

Pediatric considerations

• Beau’s lines may appear after high fevers, severe infections, or trauma in children.

• Assess for underlying systemic or nutritional disorders if multiple lines are present.

Geriatric considerations

• Older adults may develop Beau’s lines more readily due to comorbidities or impaired nail growth.

• Lines may serve as a historical record of recent systemic stress.

Key points

• Beau’s lines are a visible marker of interrupted nail growth due to systemic stress.

• Transverse grooves correspond to the timing and duration of the insult.

• They are non-specific but provide valuable clinical and chronological information.

References

1. Beau J. Les ongles dans les maladies générales. Paris Med. 1846;11:438–440.

2. Scher RK, Daniel CR. Nail Disorders: Diagnosis and Management. 2nd ed. Philadelphia, PA: Saunders; 2005.

3. Bolognia JL, Schaffer JV, Cerroni L. Dermatology. 4th ed. Philadelphia, PA: Elsevier; 2018.

4. McCance KL, Huether SE, Brashers VL, Rote NS. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 8th ed. Maryland Heights, MO: Mosby Elsevier; 2019.

5. Butler DS. Clinical Examination of the Nails. Med Clin North Am. 2011;95(6):1179–1193.