10.2 Nail Diseases, Disorders, Contraindications & Sanitization

1. State Board Regulatory Scope: Disorders vs. Diseases

In professional nail care, onychosis (pronounced on-ih-KOH-sis) is the general medical term applied to any disease, deformity, or condition of the natural nail unit.

Cosmetology licensing laws establish a rigorous legal boundary regarding which nail conditions may receive salon services and which require immediate medical referral:

1. Nail Disorders: Non-infectious structural, mechanical, or cosmetic irregularities caused by minor external trauma, genetics, systemic imbalance, or normal aging. Cosmetologists are legally permitted to service clients with nail disorders, provided the skin is unbroken and services are modified to protect the natural nail.
2. Nail Diseases: Pathological conditions caused by infectious biological agents (fungi, bacteria, viruses) or severe inflammatory dermatoses. Cosmetologists are STRICTLY FORBIDDEN from performing any salon service on a client presenting with a nail disease or inflamed/broken skin. The client must be tactfully referred to a licensed physician or dermatologist.

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2. Salon-Treatable Nail Disorders (Cosmetic Services Permitted)

+─────────────────────────────────────────────────────────────────────────+
|             SALON-TREATABLE NAIL DISORDERS (SERVICE PERMITTED)          |
+──────────────────────┬──────────────────────────────────────────────────+
| DISORDER             | CLINICAL PRESENTATION & ETIOLOGY                 |
+──────────────────────┼──────────────────────────────────────────────────+
| Beau's Lines         | Transverse horizontal depressions (matrix shock) |
| Blue Fingernails     | Cyanotic bluish plate (poor circulation)         |
| Splinter Hemorrhage  | Microscopic vertical red/black streaks (trauma)  |
| Corrugations         | Vertical ridges from aging/dryness (buff gently) |
| Eggshell Nails       | Thin, white, hyper-flexible curved plates        |
| Hangnail (Agnail)    | Split living skin tags at perionychial fold      |
| Leukonychia          | White micro-spots from focal matrix trauma       |
| Melanonychia         | Longitudinal dark melanin bands                  |
| Onychophagy          | Habitual nail-biting; shortened nail plate       |
| Onychorrhexis        | Split, brittle nails with longitudinal furrows   |
| Pincer / Plicatured  | Extreme transverse curvature pinching soft bed   |
| Nail Pterygium       | Abnormal forward growth of living skin on plate  |
+──────────────────────┴──────────────────────────────────────────────────+

Beau's Lines

• Presentation: Visible horizontal (transverse) depressions, grooves, or furrows running across the width of the nail plate.
• Etiology: Occurs when mitotic cell division in the nail matrix is temporarily arrested or severely slowed due to major systemic trauma, high fever (e.g., pneumonia, measles), major surgery, coronary arrest, or focal matrix injury.
• Salon Protocol: Service may proceed with gentle care. Buff the plate very lightly; avoid aggressive downward pressure that could fracture the thinned depression. As the matrix recovers, the groove grows out distally with the plate.

Blue Fingernails

• Presentation: The tissue beneath the nail plate exhibits a distinct bluish or purplish cast.
• Etiology: Caused by systemic cyanosis—a lack of circulating oxygenated hemoglobin resulting from poor peripheral blood circulation, cold exposure, respiratory illness, or cardiovascular disease.
• Salon Protocol: Service is permitted with gentle massage to stimulate local circulation. However, if blue discoloration appears suddenly without cold exposure, recommend that the client consult a physician.

Bruised Nail Beds & Splinter Hemorrhages

• Bruised Nail Beds: Blood clots (hematomas) form beneath the nail plate due to acute mechanical trauma (e.g., crushing injury). The blood adheres to the underside of the plate and grows out toward the free edge. Service is permitted if there is no active bleeding, swelling, or open wound.
• Splinter Hemorrhages: Tiny, thin, vertical red, brown, or black longitudinal streaks appearing under the nail plate. Caused by physical trauma or localized micro-capillary rupture along the bed epithelium tracks. Service is permitted.

Ridges (Corrugations)

• Vertical Ridges: Longitudinal ridges running from matrix to free edge. Extremely common, harmless, and primarily associated with normal biological aging, cellular dehydration, or genetics.
  • Protocol: Buff very lightly with a 240+ grit fine buffer and apply ridge-filling base coats. Avoid over-buffing, which excessively thins the plate.
• Horizontal Furrows: Transverse ridges across the plate; treat similarly to Beau's lines.

Eggshell Nails (Hapalonychia)

• Presentation: Noticeably thin, soft, white, translucent nail plates that are hyper-flexible and curve over the free edge.
• Etiology: Caused by chronic systemic disease, dietary deficiencies, nervous disorders, or heredity.
• Salon Protocol: Handle with extreme gentleness. Use 240+ grit soft files, file without excessive downward pressure, avoid soaking for extended periods, and apply protective overlays or strengthening lacquers.

Hangnail (Agnail)

• Presentation: A condition where the living skin around the nail plate (perionychium or eponychial fold) splits, tears, and forms a loose tag of skin.
• Etiology: Caused by excessive cutaneous dryness, skin dehydration, exposure to harsh solvents, or habitual nail biting.
• Salon Protocol: Cleanse and disinfect the area thoroughly. If a loose tag of dead skin is snagging, carefully nip the detached dead tag off flush with the skin using sanitized cuticle nippers. Never cut into living skin or rip the tag away.

Leukonychia (White Spots)

• Presentation: Whitish micro-discolorations appearing as small spots (leukonychia punctata) or transverse bands across the nail plate.
• Etiology: Caused by minor focal mechanical micro-trauma to the matrix (e.g., aggressive pushing of the eponychium) that traps microscopic air bubbles between incompletely keratinized cell layers. State Board Myth: Leukonychia is NOT caused by calcium or zinc deficiency. It naturally grows out with the plate.

Melanonychia

• Presentation: Significant darkening or black/brown pigmentation of the nail plate forming a distinct longitudinal band running from matrix to free edge.
• Etiology: Increased deposition of melanin by activated matrix melanocytes. Common and normal in individuals with deeply pigmented skin tones.
• Critical Clinical Rule: If a dark pigmented band appears suddenly in a fair-skinned individual, changes rapidly, widens, or extends into the eponychium (Hutchinson's sign), refuse service and refer immediately to a dermatologist for subungual melanoma screening.

Onychophagy (Bitten Nails)

• Presentation: Severely shortened, deformed nail plates with chewed, raw, or calloused surrounding perionychial skin resulting from habitual nail biting.
• Salon Protocol: Service is permitted provided the skin is unbroken and free of infection. Frequent manicures, regular application of cuticle oils, and artificial enhancements (acrylic/gel overlays) can protect the plate and help break the habit.

Onychorrhexis

• Presentation: Brittle, fragile nails characterized by a series of longitudinal splits, microscopic surface fractures, and deep vertical ridges.
• Etiology: Caused by aggressive chemical exposure (acetone, detergents), physical matrix injury, hereditary dryness, or endocrine imbalances.
• Salon Protocol: Recondition with warm oil manicures, hydrating serums, and conditioning base coats. Use ultra-gentle filing techniques and avoid harsh solvent exposure.

Plicatured Nails & Pincer Nails (Trumpet Nails)

• Plicatured Nail (Folded Nail): Highly curved nail plate caused by matrix injury or genetics, with one or both edges folded down at a 90-degree angle into the soft tissue, predisposing to ingrown nails.
• Pincer Nail (Trumpet Nail): The transverse curvature of the nail plate increases dramatically toward the free edge, curling inward into a tight cone or tube that severely pinches the nail bed soft tissue.
• Salon Protocol: Service with extreme care. Carefully smooth the free edge without cutting into the lateral sidewalls to avoid puncture wounds.

Nail Pterygium

• Presentation: An abnormal forward overgrowth of living eponychial or hyponychial skin that adheres tenaciously to the dorsal surface of the nail plate and stretches forward like a wing.
• Etiology: Caused by severe burns, chronic mechanical trauma, or autoimmune dermatoses (e.g., lichen planus).
• State Board Mandate: NEVER PUSH BACK, CUT, OR NIP NAIL PTERYGIUM. It is living vascular tissue; cutting it causes severe bleeding and permanent scarring.

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3. Infectious Nail Diseases (Absolute Contraindications)

Cosmetologists encountering any of the following infectious diseases or active inflammatory conditions must refuse all services, explain the safety rationale tactfully, and refer the client to a medical physician.

+─────────────────────────────────────────────────────────────────────────+
|          INFECTIOUS NAIL DISEASES (ABSOLUTE CONTRAINDICATIONS)          |
+──────────────────────┬──────────────────────────────────────────────────+
| DISEASE              | CLINICAL PRESENTATION & PATHOLOGY                |
+──────────────────────┼──────────────────────────────────────────────────+
| Onychomycosis        | Fungal infection; thickened, yellow, crumbly     |
| Paronychia           | Bacterial infection of folds; red, swollen, pus  |
| Pseudomonas          | Opportunistic bacterium; green/black pyocyanin   |
| Onychia              | Deep bacterial inflammation of matrix with pus   |
| Onycholysis          | Separation of plate from bed (whitish/opaque)    |
| Onychomadesis        | Complete shedding of plate starting at matrix    |
| Pyogenic Granuloma   | Highly vascular red inflamed granulation polyp   |
| Tinea Pedis          | Fungal dermatophyte infection of foot / toes     |
+──────────────────────┴──────────────────────────────────────────────────+

Onychomycosis (Tinea Unguium)

• Pathology: A chronic fungal infection of the nail plate primarily caused by dermatophytes (Trichophyton rubrum), non-dermatophyte molds, or Candida yeasts.
• Clinical Signs: Whitish or yellowish patches, hyperkeratotic subungual debris, thickened plate, brittle crumbling texture, foul odor, and plate distortion.
• Action: DO NOT SERVICE. Refer to a dermatologist.

Paronychia

• Pathology: An acute or chronic bacterial infection (most commonly Staphylococcus aureus or Streptococcus) of the living skin folds surrounding the nail plate (perionychium and eponychium).
• Clinical Signs: Intense localized erythema (redness), throbbing pain, localized edema (swelling), elevated heat, and accumulation of purulent exudate (pus).
• Action: DO NOT SERVICE. Highly contagious. Refer immediately to a physician.

Pseudomonas aeruginosa (Bacterial Nail Infection)

• Pathology: An opportunistic gram-negative bacterial infection that colonizes the moist, warm space between a lifted artificial enhancement (acrylic/gel) and the natural nail plate.
• Etiology: Pseudomonas feeds on moisture, dead skin cells, and organic debris trapped beneath lifted product. As the colony metabolizes, it produces characteristic green, dark olive, and black pigments (pyocyanin and pyoverdine).
• State Board Critical Rule:
  • In early cosmetology literature, this condition was mistakenly called "nail mold" or "fungus." It is 100% bacterial.
  • If a green spot is revealed during enhancement removal: SAFELY REMOVE ALL ENHANCEMENT PRODUCT, cleanse the nail plate thoroughly, dry it completely, and DO NOT REAPPLY ANY PRODUCT OR POLISH. Covering a Pseudomonas infection seals in moisture and accelerates deep bacterial destruction of the nail bed.

Onychia

• Pathology: A severe, deep-seated bacterial inflammation of the nail matrix and nail fold tissues.
• Clinical Signs: Redness, swelling, intense pain, pus formation, and eventual detachment and shedding of the nail plate from the matrix.
• Action: DO NOT SERVICE. Refer to a medical doctor.

Onycholysis

• Pathology: The painless lifting and separation of the natural nail plate from the underlying vascular nail bed, typically beginning at the free edge and progressing toward the lunula.
• Etiology: Caused by mechanical trauma (e.g., using nails as tools, long enhancements catching on objects), chemical overexposure (harsh primers, solvent contact), allergic contact dermatitis from acrylates/gels, or underlying fungal infection.
• Clinical Appearance: The separated area appears opaque, white, yellow, or grayish due to air trapped between the plate and bed.
• Action: If there is no infection and no open skin, the non-separated portions may be manicured gently with all enhancement applications withheld until the plate re-adheres as it grows out. If discoloration or infection is present, DO NOT SERVICE.

Onychomadesis

• Pathology: The complete separation and shedding of the entire nail plate from the nail bed, originating at the proximal matrix area.
• Etiology: Caused by acute matrix shutdown following severe systemic illness (e.g., hand-foot-and-mouth disease, chemotherapy), major localized matrix trauma, or severe deep paronychia.
• Action: DO NOT SERVICE until the acute underlying cause has resolved and the matrix begins producing a healthy new plate.

Pyogenic Granuloma

• Pathology: A severe, highly vascular inflammatory lesion characterized by an overgrowth of bright red granulation tissue on the nail bed or surrounding folds.
• Clinical Signs: A fleshy, bleeding, bright red or purple nodule that easily bleeds upon minimal contact.
• Action: DO NOT SERVICE. Refer immediately to a physician.

Tinea Pedis (Athlete's Foot)

• Pathology: A contagious superficial fungal dermatophyte infection of the plantar skin and interdigital web spaces of the feet.
• Clinical Signs: Red, itchy, burning, peeling, scaling, or blistering skin between the toes or on the soles.
• Action: DO NOT SERVICE. All pedicure services must be refused and the client referred to a podiatrist or physician.

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4. Master State Board Decision Matrix