Onycholysis

2026-03-18 🇷🇴 Română

What is it?

Onycholysis is the painless separation of the nail plate from the underlying nail bed. It usually starts at the free edge (tip) of the nail and progresses toward the base. The separated portion of the nail appears white or yellowish because air fills the space between the nail plate and the nail bed.

Onycholysis is not a disease itself but a sign that can result from many different causes — including trauma, skin conditions like psoriasis, fungal infections, certain medications, and occasionally thyroid or other systemic diseases. It is one of the most common nail complaints seen by dermatologists and affects fingernails more often than toenails.

In most cases, onycholysis is harmless and reversible once the underlying cause is identified and addressed. However, the detached nail creates a moist, enclosed space that is prone to secondary infections, particularly by yeast (Candida) or bacteria (Pseudomonas), which can cause the nail to turn green or develop an unpleasant odor.

What does it look like?

  • White or yellowish area: The detached portion of the nail appears white, opaque, or yellow-white, in contrast to the normal pink nail
  • Starts at the tip: Separation typically begins at the free (distal) edge and extends backward toward the base of the nail
  • Smooth border or irregular border: Depending on the cause, the line where normal and detached nail meet may be smooth or jagged
  • Nail surface: The nail plate itself may appear normal or may show additional changes (pitting, ridging, thickening) depending on the cause
  • Color changes: A green discoloration suggests bacterial infection (Pseudomonas); yellow-brown may suggest fungal infection; hemorrhagic spots suggest drug-related causes

Where does it appear?

  • Fingernails: Most commonly affected, especially the ring finger and long (middle) finger of the dominant hand
  • Toenails: Frequently affected by trauma-related and fungal onycholysis, particularly the great toenail
  • Single nail vs. multiple nails: Trauma usually affects one or two nails; psoriasis, medications, and systemic causes tend to involve several or all nails
  • Pattern: Distal onycholysis (starting at the tip) is most common; lateral onycholysis (starting from the side) is also seen, particularly in psoriasis

Associated features

Onycholysis may be accompanied by:

  • Subungual hyperkeratosis: Buildup of white or yellow scales beneath the nail (common in psoriasis and onychomycosis)
  • Nail pitting or ridging: Small depressions or lines on the nail surface (psoriasis, eczema)
  • Nail discoloration: Green (Pseudomonas infection), yellow-brown (fungal), oil-drop spots (psoriasis)
  • Skin changes: Psoriatic plaques on the body, dermatitis on the hands, or fungal infection between the toes
  • Pain: Onycholysis itself is typically painless; pain suggests secondary infection, subungual tumor, or glomus tumor
  • Odor: An unpleasant smell may indicate secondary bacterial or yeast infection in the detached space

When to see a doctor

Consider medical evaluation for:

  • Onycholysis affecting multiple nails without a clear cause (such as trauma) — this may signal psoriasis, thyroid disease, or another systemic condition
  • Green, yellow, or brown discoloration of the detached area, suggesting infection
  • Pain, swelling, or tenderness in the affected nail — pain under a nail with onycholysis may indicate a subungual tumor
  • Onycholysis that does not improve after several months despite avoiding trauma and irritants
  • New nail separation after starting a medication, especially antibiotics (tetracyclines, fluoroquinolones) combined with sun exposure
  • Onycholysis in a single nail that is slowly progressive and unresponsive to treatment — chronic unexplained onycholysis in a single nail may rarely indicate subungual squamous cell carcinoma
References

Primary Sources

  1. Onycholysis - Kechijian P (1985). J Am Acad Dermatol. 12(3):552-560. PMID: 3886720

    • URL: https://pubmed.ncbi.nlm.nih.gov/3886720/
    • Key findings: Classic foundational review of onycholysis — comprehensive classification by etiology (traumatic, systemic, cutaneous, idiopathic), diagnostic approach, and management principles

  2. Onycholysis: a comprehensive review and update - Lee JH, Lipner SR (2022). Ann Med. 54(1):1005-1017. PMID: 35238267

    • URL: https://pubmed.ncbi.nlm.nih.gov/35238267/
    • Key findings: Modern comprehensive review covering epidemiology, classification, pathophysiology, clinical features, differential diagnosis, and evidence-based management of onycholysis

  3. Nail changes in systemic diseases - Zaiac MN, Walker A (2013). Clin Dermatol. 31(5):627-649. PMID: 24079592

    • URL: https://pubmed.ncbi.nlm.nih.gov/24079592/
    • Key findings: Review of nail findings (including onycholysis) associated with systemic diseases — thyroid disease (Plummer's nails), iron deficiency, connective tissue diseases, yellow nail syndrome

  4. Onychoscopy: dermoscopy of the nails - Sar-Pomian M, Czarnecka-Operacz M, Tosti A (2024). Dermatol Clin. PMID: 39021761

    • URL: https://pubmed.ncbi.nlm.nih.gov/39021761/
    • Key findings: Dermoscopic examination techniques for nail disorders; differential diagnosis of onycholysis by dermoscopy including psoriatic, traumatic, infectious, and drug-induced patterns

  5. Nail psoriasis: an updated review - Rachadi H, Chiheb S (2024). Int J Dermatol. PMID: 38520074

  6. Overview of nail disorders - Tosti A, Piraccini BM. UpToDate. Last updated 2025.

  7. Dermoscopy of nonpigmented nail lesions - Tosti A, Starace M. UpToDate. Last updated 2025.

Additional Sources

Research Notes