Onycholysis: Why Your Nail Is Separating & What to Do

What Is Onycholysis?

Onycholysis is the painless separation of the nail plate from the nail bed beneath it. The lift begins at the free edge of the nail (the tip) and can spread proximally toward the cuticle. Where the nail has lifted, a white, yellow, or greenish opaque area appears — this is actually air beneath the nail plate, or sometimes accumulated debris or secondary infection in the space.

The nail plate itself remains structurally intact in most cases of onycholysis — it is the bond between the plate and the nail bed that has broken down. This is an important distinction from nail fragility or crumbling, which signals structural damage to the plate itself.

Onycholysis is not a diagnosis in its own right but a sign — a visible result of many possible underlying processes. Identifying and removing the cause is the foundation of treatment. The separated nail cannot be re-attached under any circumstances: new nail must grow out from the matrix (the growth center beneath the cuticle) and, over time, replace the detached section. This process takes months.

What Causes Nails to Separate?

The causes of onycholysis are numerous, and more than one may operate at the same time. They are broadly categorized as local or systemic.

Local Causes (Most Common)

Trauma The most frequent single cause. The nail plate can be separated by:

• Aggressive cleaning under the nail with a sharp tool (a common habit that damages the hyponychium — the skin seal at the nail's free edge — and creates a space for further separation)
• Tight footwear repeatedly pressing on the big toenail during walking or sport
• Catching the nail on fabric or other objects, causing sudden avulsion of part of the plate
• Occupational repeated impact to the fingertip
• Artificial nails placed with excessive filing of the natural nail plate

Moisture and Maceration Prolonged or repetitive water exposure softens the nail plate, weakens the nail bed attachment, and creates a moist environment ideal for Candida and bacteria. This is particularly relevant in:

• People who wash hands or submerge hands in water frequently
• Wearing occlusive gloves for long periods without ventilation
• Hyperhidrosis (excessive sweating)

Nail Cosmetics and Chemicals Nail hardeners, acetone-based removers, acrylic or gel products (especially improper removal), and formaldehyde-containing products can damage the nail bed adhesion. Gel product lifting that is then peeled — rather than properly soaked off — can cause acute, dramatic onycholysis. See how to remove gel nails safely for the correct technique.

Fungal Nail Infection Subungual hyperkeratosis (debris build-up under the nail from onychomycosis) exerts pressure that lifts the nail from its bed. Onycholysis is a classic feature of fungal nail infection. Distinguishing fungal from non-fungal onycholysis requires laboratory testing (KOH microscopy, nail culture).

Allergic Contact Dermatitis Allergy to nail cosmetic ingredients — particularly tosylamide/formaldehyde resin in conventional nail lacquers, or acrylates in gel systems — can cause allergic inflammation of the nail bed, disrupting attachment.

Systemic Causes

Psoriasis Nail psoriasis is the most important systemic cause of onycholysis. Up to 80% of patients with nail psoriasis develop onycholysis, along with pitting, oil-drop (salmon-patch) discoloration, and subungual hyperkeratosis. Nail psoriasis may occur even when skin psoriasis is absent or mild. The mechanism involves inflammation at the nail bed and hyponychium, degrading the attachment to the nail plate.

Thyroid Disease Onycholysis — particularly the characteristic form known as "Plummer's nails" — is a recognized feature of hyperthyroidism. Any unexplained onycholysis, especially in the absence of obvious local cause, is an indication to test thyroid function. The association is strong enough that it has prompted recommendations for TSH testing in unexplained cases.

Iron Deficiency Anemia Iron deficiency can cause nail changes including koilonychia (spoon-shaped nails) and, less commonly, onycholysis.

Drug-Induced Onycholysis Several medications predictably cause photo-onycholysis (onycholysis triggered by sun exposure on the drug) or direct nail bed toxicity:

• Tetracyclines (doxycycline in particular) — the most commonly reported photo-onycholysis drug; may affect all nails of sun-exposed hands
• Psoralens (PUVA therapy) — photo-sensitizing agents used in psoriasis treatment
• Taxanes (paclitaxel, docetaxel) — chemotherapy drugs causing subungual hemorrhage and separation
• Fluoroquinolone antibiotics, capecitabine, and targeted cancer therapies (EGFR inhibitors) have also been reported

Other Systemic Associations Onycholysis has been reported in lupus erythematosus, reactive arthritis, connective tissue disorders, and — rarely — as a sign of internal malignancy. These are less common causes but important in the diagnostic evaluation of unexplained multi-nail onycholysis.

What Onycholysis Looks Like

The appearance can vary depending on the cause:

• White or pale yellow opacity beginning at the free edge, with a curved or irregular border proximally — the most common appearance (seen in trauma, moisture, and idiopathic cases)
• Salmon-pink (oil-drop) patch of discoloration visible through the nail plate — strongly suggestive of nail psoriasis
• Green or black discoloration in the lifted space — indicates secondary Pseudomonas aeruginosa infection of the exposed nail bed; the green pigment (pyocyanin) is characteristic of this bacterium
• Yellow-brown opacity with subungual debris — suggests concurrent fungal infection

Treatment: What Actually Works

The Foundational Rule: You Cannot Re-Attach Lifted Nail

This is the single most important fact about onycholysis: the separated section of nail cannot be reattached, and no treatment will reconnect it to the nail bed. The only resolution is for new, healthy nail to grow from the matrix (growth center) and progressively replace the detached nail as it is trimmed away. Toenail growth averages 1–1.5 mm per month; full resolution of a severely affected big toenail can take 12–18 months.

Step 1 — Identify and Remove the Cause

Before the nail can recover, the precipitating factor must be eliminated:

• Stop all aggressive nail cleaning beneath the plate — never insert implements under the nail
• Stop peeling or picking at lifted nail edges — this extends the separation
• Identify and discontinue any causative drug (inform your prescriber)
• Treat fungal infection with appropriate antifungal therapy if confirmed
• Manage psoriasis — systemic therapy (biologics, methotrexate) or intralesional corticosteroid injections to the nail fold can reduce nail psoriasis severity and allow the nail to re-attach

Step 2 — Keep the Nail Short and the Space Dry

• Trim the detached section regularly — cut the lifted nail back to where it still adheres to the nail bed, keeping the free edge as short as safely possible. This prevents the space from accumulating debris, moisture, and organisms.
• Keep hands dry after washing — gently dry between and around the nails
• Wear gloves (cotton inside vinyl or nitrile) for dishwashing, cleaning, and all prolonged water contact
• Avoid prolonged submersion of hands in water

Step 3 — Manage Secondary Infection

The space beneath lifted nail is a warm, moist, protected environment in which bacteria and yeast thrive. Green discoloration indicates Pseudomonas colonization; treatment options include diluted acetic acid (white vinegar) soaks, topical ciprofloxacin drops (off-label), or — when indicated — systemic antibiotics. Candida overgrowth responds to topical or oral antifungals.

Step 4 — Treat the Underlying Condition

Specific treatments for the systemic cause can dramatically accelerate recovery:

• Psoriasis: Topical high-potency corticosteroids or intralesional triamcinolone injections into the nail fold reduce inflammation and allow nail bed re-attachment; biologic therapies with nail psoriasis efficacy include ixekizumab and secukinumab
• Hyperthyroidism: Once thyroid function is normalized with antithyroid medications or other treatment, nails typically recover spontaneously
• Iron deficiency: Correcting iron stores through supplementation or addressing the underlying cause usually allows nail changes to improve

What Not to Do

• Do not apply nail lacquer or gel to detached nail — this traps moisture and bacteria in the lifted space
• Do not use nail glue to try to re-stick the lifted portion — it seals in infection
• Do not pull or tear the lifted nail — this causes pain and potential injury to the nail bed

Photo-Onycholysis: A Special Case

Photo-onycholysis is onycholysis triggered by ultraviolet light exposure in combination with a photosensitizing drug — most commonly doxycycline. The mechanism involves UV-induced damage to the nail bed, causing acute separation. It typically affects the index, middle, and ring fingers (most sun-exposed) and can affect all nails in severe cases. Management: discontinue the drug if possible; if doxycycline is clinically necessary, wear gloves outdoors and apply sunscreen to the dorsal hands. Resolution follows once the drug is stopped, but the affected nails must still grow out.

When to See a Dermatologist

Onycholysis with an obvious local cause (e.g., you know you had gel nails peeled off, or started doxycycline last month) can be managed conservatively at home with the measures above. See a dermatologist or GP if:

• Multiple nails are affected without a clear local cause
• Onycholysis is progressing despite conservative care
• You have other skin or joint symptoms suggestive of psoriasis or a connective tissue disorder
• There is significant green, black, or brown discoloration in the lifted space
• You need blood tests to exclude thyroid disease, iron deficiency, or anemia
• The nail has been lifted for more than 3–4 months without improvement