Onycholysis
Onycholysis is the painless separation of the nail plate from the underlying nail bed. It usually starts at the free (distal) edge or along the sides and gradually works back toward the proximal nail fold.
The underlying problem is a breakdown of the epidermal–dermal attachment between the underside of the nail plate and the longitudinal ridges of the nail bed:
- Normally the plate is anchored firmly to the bed by cell-to-cell junctions (desmosomes and the onychocorneal band).
- Mechanical stress, chemicals, microorganisms or a flare of inflammation can break this attachment. The plate lifts and leaves a gap beneath it, the subungual space.
- Air gets into this space, and it becomes a trap for dirt, keratin debris, water and opportunistic organisms (fungi and bacteria), which in turn drives the separation further.
Main Groups of Causes
- Mechanical and Chemical Factors:
- Repeated microtrauma: cleaning under the nails with sharp objects, heavy typing, gel or acrylic manicures, and frequent minor knocks.
- Chemical exposure: harsh detergents, hair and nail salon chemicals, acetone-based removers, and formaldehyde in low-quality nail polish.
- Infection Under the Nail:
- Onychomycosis (nail fungus): dermatophytes (such as Trichophyton rubrum) and Candida yeasts damage the nail bed, causing hyperkeratosis and lifting of the plate.
- The bacterium Pseudomonas aeruginosa: thrives in the moist space under a lifted nail and produces a pigment that turns the nail green (green nail syndrome).
- Chronic Skin Conditions:
- Nail psoriasis: psoriatic inflammation in the nail bed produces oil-drop spots or a sharply defined red border, and over time the plate splits away.
- Nail lichen planus, atopic dermatitis and irritant contact dermatitis.
- Systemic Disease and Medications:
- Thyroid disorders: hyperthyroidism (which produces Plummer's nails) or hypothyroidism.
- Drug-induced phototoxicity (photo-onycholysis): taking photosensitizing drugs (tetracycline, doxycycline, fluoroquinolones, psoralens) combined with direct UV exposure.
- Iron-deficiency anemia, diabetes and poor peripheral circulation.
The most common mistake in managing onycholysis is jumping straight to nail thinning or antifungal creams before the trigger has been identified. At Haute-Derma, our workup always separates primary onycholysis caused by mechanical or chemical injury from secondary onycholysis due to psoriasis, fungal infection or thyroid disease. Combining nail dermoscopy (onychoscopy), KOH microscopy for fungi and screening for systemic disease lets us remove the root cause and prevent permanent nail bed keratinization.
Clinical Features and Patterns
Clinical Signs
- Change in nail color: the detached area loses its natural pink tone and looks grayish-white or pale yellow because of the air trapped underneath.
- Secondary discoloration from microorganisms:
- Green or blue-black: infection with Pseudomonas aeruginosa.
- Brown or black: old blood, or keratin debris colonized by fungi.
- Cloudy and moist: yeast infection with Candida albicans, often with paronychia.
- Progression to nail bed keratinization: if the nail bed stays exposed to air for more than 6–12 months, its epidermis turns into a thickened, callus-like surface that can no longer hold on to the plate. A newly grown nail then has great difficulty reattaching.
Classification by Location
- Distal-lateral onycholysis: the most common type. It starts at the tip or a side corner of the nail and is mostly caused by mechanical injury, chemicals or onychomycosis.
- Proximal onycholysis: separation that begins at the base of the nail. It is very rare and usually points to serious systemic illness, a side effect of chemotherapy, or severe fungal infection in an immunocompromised patient.
Diagnosis and Treatment at Haute-Derma
Our Diagnostic Workup
- Onychoscopy (nail dermoscopy): we look closely at the edge of the detached area. A smooth, even edge suggests trauma; a jagged, spiky edge suggests fungus; a pinkish-red border suggests psoriasis.
- Direct KOH microscopy (10–20% KOH): debris must be taken from the deepest point of the separated area to look for fungal spores and hyphae.
- Systemic assessment: when every nail is affected and there is no obvious skin disease, we order thyroid function tests (FT3, FT4, TSH) and a complete blood count.
Treatment and Recovery Care
- Trimming the detached nail (clipping/debridement): using sterile nippers, we remove as much of the lifted plate as possible. This eliminates the pocket where microbes collect, lets the nail bed breathe, and allows topical treatment to reach the affected area directly.
- Treating the cause:
- Pseudomonas infection: soaks in 1% acetic acid (diluted vinegar), or topical ciprofloxacin/tobramycin twice daily.
- Onychomycosis: topical antifungals (amorolfine, ciclopirox) or oral agents (terbinafine, itraconazole) if KOH is positive.
- Psoriasis or lichen planus: a potent topical corticosteroid combined with calcipotriol applied to the nail bed.
- Protecting the Nail Bed:
- Dry the nails thoroughly every time you wash your hands or feet.
- Wear cotton-lined rubber gloves for housework or any contact with chemicals.
- Never poke sharp tools into the gap under the nail.
- Stop all nail polish and gel or acrylic extensions until the new nail has fully grown back.
