One-liner#
Evaluate nail changes to distinguish common conditions (onychomycosis, trauma, psoriasis) from concerning findings (melanonychia requiring melanoma evaluation), initiating appropriate treatment while knowing when to refer.
Quick nav#
- Red flags / send to ED
- Key history
- Focused exam
- Differential (quick pattern recognition)
- Workup
- Initial management
- Management by diagnosis
- Follow-up
- Patient instructions
- Smartphrase snippets
Red flags / send to ED#
- Acute paronychia with signs of deep space infection (severe pain, inability to flex finger)
- Subungual hematoma with suspected fracture and significant nail bed injury
Urgent (not ED, but expedited referral):
- Melanonychia (longitudinal pigmented band) with concerning features → derm referral within 2 weeks
- Rapidly growing nail mass
- Nail changes with systemic symptoms suggesting underlying disease
Key history#
Nail change characteristics:
- Which nails affected: single vs multiple, fingernails vs toenails
- Duration: acute vs chronic
- Progression: stable, improving, worsening
- Symptoms: pain, tenderness, discharge
Associated factors:
- Trauma history
- Occupation (wet work, chemicals)
- Nail care habits (manicures, artificial nails, nail biting)
- Footwear (tight shoes, athletic activities)
Systemic associations:
- Psoriasis or psoriatic arthritis
- Thyroid disease
- Diabetes
- Peripheral vascular disease
- Immunosuppression
- Medications (chemotherapy, retinoids)
Family history:
- Psoriasis
- Nail disorders
Focused exam#
Nail anatomy to assess:
- Nail plate: color, texture, thickness, shape
- Nail bed: visible through nail plate
- Lunula: half-moon at base
- Cuticle and nail folds: inflammation, swelling
- Hyponychium: under free edge of nail
Key findings:
| Finding | Description | Associations |
|---|---|---|
| Onycholysis | Separation of nail from nail bed | Onychomycosis, psoriasis, trauma, thyroid disease |
| Subungual hyperkeratosis | Thickening under nail | Onychomycosis, psoriasis |
| Pitting | Small depressions in nail plate | Psoriasis, alopecia areata, eczema |
| Beau’s lines | Transverse grooves | Systemic illness, trauma, chemotherapy |
| Longitudinal ridging | Vertical ridges | Normal aging, lichen planus |
| Koilonychia | Spoon-shaped nails | Iron deficiency, hemochromatosis |
| Clubbing | Bulbous fingertips, loss of nail angle | Pulmonary disease, cardiac disease, GI disease |
| Splinter hemorrhages | Linear red-brown lines | Trauma, endocarditis, vasculitis |
| Terry’s nails | White nails with narrow pink band | Cirrhosis, CHF, diabetes |
| Half-and-half nails | Proximal white, distal brown | Chronic kidney disease |
| Melanonychia | Longitudinal pigmented band | Benign (common in dark skin), subungual melanoma |
Differential (quick pattern recognition)#
Common/likely (outpatient)#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Onychomycosis | “Thick yellow nails,” “fungus,” “crumbly” | Toenails > fingernails; chronic; often multiple nails | Thickened, yellow, crumbly nail; subungual debris; onycholysis | Confirm with KOH/culture; oral or topical antifungal |
| Nail psoriasis | “Pitted nails,” “nails lifting” | History of psoriasis; may have joint symptoms | Pitting; onycholysis; oil spots; subungual hyperkeratosis | Treat psoriasis; topical steroids; derm referral if severe |
| Traumatic nail changes | “Hit my nail,” “dropped something on it” | Clear trauma history; single nail | Subungual hematoma; nail dystrophy; Beau’s lines | Reassurance; nail will grow out; drain hematoma if acute and painful |
| Paronychia (acute) | “Red swollen around nail,” “pus” | Acute onset; painful; often after manicure or nail biting | Erythema, swelling of nail fold; may have pus | Warm soaks; I&D if abscess; antibiotics if cellulitis |
| Paronychia (chronic) | “Always red around nails,” “wet work” | Chronic; multiple nails; wet work exposure | Boggy nail folds; loss of cuticle; nail dystrophy | Avoid wet work; topical antifungal/steroid; keep dry |
| Ingrown toenail | “Nail growing into skin,” “painful toe” | Great toe; tight shoes; improper trimming | Nail edge embedded in lateral fold; erythema; granulation tissue | Conservative care; partial nail avulsion if severe |
| Habit-tic deformity | “Ridged thumbnail,” “pick at my nails” | Thumbnail; horizontal ridges; nail picking habit | Central longitudinal depression with horizontal ridges | Break habit; reassurance |
Can’t-miss / urgent#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Subungual melanoma | “Dark streak in nail,” “new pigment” | Single nail; longitudinal pigmented band; changing | Melanonychia with Hutchinson sign (pigment on nail fold); irregular band | Urgent derm referral for nail matrix biopsy |
| Squamous cell carcinoma | “Wart that won’t go away,” “under nail” | Chronic “wart” or non-healing lesion; single digit | Verrucous growth; may have nail destruction | Derm referral for biopsy |
| Glomus tumor | “Exquisite pain,” “can’t touch it” | Severe pain with cold or pressure; single nail | Blue-red discoloration under nail; point tenderness | MRI; surgical excision |
| Subungual exostosis | “Bony bump under nail,” “painful” | Bony growth under nail; often great toe | Hard nodule lifting nail; visible on X-ray | X-ray; surgical excision |
| Nail clubbing (new) | “Fingertips getting bigger” | New onset; may have respiratory or GI symptoms | Loss of nail angle; bulbous fingertips | CXR; evaluate for underlying cause |
Workup#
Most nail conditions are diagnosed clinically. Testing confirms onychomycosis before treatment.
| Test | When to order | Notes |
|---|---|---|
| KOH prep | Suspected onychomycosis | Scrape subungual debris; look for hyphae |
| Fungal culture | KOH negative but high suspicion; treatment failure | Takes 4-6 weeks; more specific |
| Nail clipping for PAS stain | KOH negative; need confirmation before oral therapy | Send nail clipping to pathology |
| Nail biopsy | Suspected melanoma; uncertain diagnosis | Derm performs nail matrix biopsy |
| X-ray | Suspected exostosis; trauma with possible fracture | Bony abnormalities |
When NOT to test:
- Classic psoriatic nail changes with known psoriasis
- Clear traumatic cause
- Chronic paronychia with obvious wet work exposure
Initial management#
General nail care:
- Keep nails trimmed short and straight across
- Avoid trauma
- Wear properly fitting shoes
- Keep nails dry
- Avoid harsh chemicals and excessive water exposure
Management by diagnosis#
Onychomycosis#
Education:
- Fungal infection of nail; very common
- Toenails more common than fingernails
- Cosmetic concern for most; can cause pain if severe
- Treatment takes months (nails grow slowly)
- Recurrence common
Confirm diagnosis before treating (especially before oral therapy):
- KOH prep, fungal culture, or nail clipping for PAS stain
- Clinical diagnosis alone has ~50% accuracy
Treatment:
Topical therapy (limited efficacy; for mild disease or patient preference):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Efinaconazole 10% solution | Apply daily x 48 weeks | None | None | $$$ | Most effective topical; expensive |
| Tavaborole 5% solution | Apply daily x 48 weeks | None | None | $$$ | Alternative topical |
| Ciclopirox 8% lacquer | Apply daily x 48 weeks | None | None | $$ | Less effective; requires debridement |
Oral therapy (more effective; for moderate-severe or patient preference):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Terbinafine | 250 mg daily x 6 weeks (fingernails) or 12 weeks (toenails) | Liver disease; drug interactions | LFTs at baseline and 6 weeks | $ | First-line oral; most effective |
| Itraconazole | 200 mg daily x 6 weeks (fingernails) or 12 weeks (toenails) OR pulse dosing | Liver disease; CHF; drug interactions | LFTs | $$ | Alternative; more drug interactions |
Terbinafine drug interactions: Avoid with CYP2D6 substrates (some antidepressants, beta-blockers)
Adjunctive measures:
- Debride thickened nails
- Treat tinea pedis concurrently
- Antifungal powder in shoes
- Discard old shoes or treat with antifungal spray
Follow-up: 3-6 months after completing treatment; nail takes 12-18 months to fully grow out.
Nail psoriasis#
Education:
- Nail involvement in up to 50% of psoriasis patients
- Associated with psoriatic arthritis
- Can occur without skin psoriasis
- Difficult to treat; responds slowly
Treatment:
Topical (first-line for mild):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Clobetasol 0.05% solution | Apply to nail folds BID x 3-6 months | None | Skin atrophy | $ | For nail matrix disease (pitting) |
| Calcipotriene 0.005% cream | Apply to nail bed daily | None | None | $$ | For nail bed disease (onycholysis) |
| Tazarotene 0.1% gel | Apply daily | Pregnancy | Irritation | $$ | May help pitting and onycholysis |
Intralesional steroids (derm-performed):
- Triamcinolone injected into nail matrix
- Effective but painful
Systemic therapy:
- For severe nail psoriasis or concurrent skin/joint disease
- Methotrexate, biologics (derm/rheum-initiated)
Follow-up: 3-6 months; derm referral if not responding to topicals.
Paronychia (acute)#
Education:
- Infection of nail fold; usually bacterial (S. aureus)
- Often follows trauma, manicure, or nail biting
- May form abscess requiring drainage
Treatment:
Early/mild (no abscess):
- Warm soaks 3-4 times daily
- May resolve without antibiotics
With cellulitis:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Cephalexin | 500 mg QID x 7 days | Cephalosporin allergy | None | $ | First-line |
| TMP-SMX DS | 1-2 tabs BID x 7 days | Sulfa allergy | None | $ | If MRSA suspected |
| Clindamycin | 300 mg TID x 7 days | C. diff history | Diarrhea | $ | Alternative |
With abscess:
- Incision and drainage
- Lift nail fold or partial nail removal if pus under nail
- Antibiotics if surrounding cellulitis
Follow-up: 48-72 hours if not improving.
Paronychia (chronic)#
Education:
- Chronic inflammation of nail folds; often multiple nails
- Associated with wet work, frequent hand washing
- Often mixed infection (Candida + bacteria)
- Must keep nails dry to heal
Treatment:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Clotrimazole 1% cream | Apply BID x 4-6 weeks | None | None | $ | Antifungal for Candida |
| Nystatin cream | Apply BID x 4-6 weeks | None | None | $ | Alternative antifungal |
| Tacrolimus 0.1% ointment | Apply BID | None | None | $$ | Anti-inflammatory; steroid-sparing |
Key management:
- Keep nails dry (most important)
- Avoid wet work; wear gloves with cotton liner
- Do not push back cuticles
- Avoid manicures until healed
Follow-up: 4-6 weeks; derm referral if not responding.
Ingrown toenail#
Education:
- Nail edge grows into lateral nail fold
- Caused by improper trimming, tight shoes, trauma
- Can become infected if untreated
Treatment:
Stage 1 (erythema, mild swelling):
- Soak in warm water
- Cotton wisp under nail edge
- Proper trimming (straight across)
- Properly fitting shoes
Stage 2 (infection, granulation tissue):
- Above measures plus antibiotics if cellulitis
- May need partial nail avulsion
Stage 3 (chronic, hypertrophied nail fold):
- Partial nail avulsion with matrix ablation (phenol or surgical)
- Podiatry referral
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Cephalexin | 500 mg QID x 7 days | Cephalosporin allergy | None | $ | If cellulitis present |
Follow-up: 1-2 weeks; podiatry referral for recurrent or stage 3.
Melanonychia (longitudinal pigmented band)#
Education:
- Pigmented streak in nail from melanin in nail matrix
- Common and usually benign in dark-skinned individuals
- In light-skinned individuals, must rule out subungual melanoma
- Concerning features require urgent evaluation
ABCDEF criteria for nail melanoma:
- Age: 50-70 years; African American, Asian, Native American
- Band: brown-black; breadth >3 mm; irregular borders
- Change: rapid increase in size or color
- Digit: thumb, index finger, great toe (most common)
- Extension: Hutchinson sign (pigment on nail fold)
- Family/personal history of melanoma
Management:
- If concerning features: urgent derm referral for nail matrix biopsy
- If benign-appearing in dark-skinned patient: can observe with photos and follow-up
- Serial photography to monitor for change
Follow-up: Derm referral if any concerning features; otherwise every 6-12 months with photos.
Follow-up#
- Onychomycosis: 3-6 months after treatment completion
- Nail psoriasis: 3-6 months
- Acute paronychia: 48-72 hours if not improving
- Chronic paronychia: 4-6 weeks
- Ingrown toenail: 1-2 weeks
- Melanonychia: Derm referral or 6-12 months with photos
Return precautions:
- Increasing pain, redness, or swelling
- Pus or drainage
- Fever
- Pigmented band getting wider or darker
- Pigment spreading to skin around nail
Patient instructions#
- Keep your nails trimmed short and straight across. Don’t round the corners.
- Keep your nails dry. Wear gloves for wet work.
- Don’t bite your nails or pick at your cuticles.
- Wear properly fitting shoes with room for your toes.
- If you have a fungal infection, it takes many months to see improvement because nails grow slowly.
- Don’t share nail clippers or files with others.
- If you notice a new dark streak in your nail, especially if it’s changing, call the office right away.
Smartphrase snippets#
.ONYCHOMYCOSIS
Onychomycosis of [toenails/fingernails]. [Number] nails affected. Diagnosis confirmed by [KOH/culture/clinical]. Plan: [terbinafine 250 mg daily x 12 weeks / topical therapy]. Baseline LFTs [ordered/normal]. Discussed that treatment takes months and nail will take 12-18 months to fully grow out. Follow-up in 3-6 months.
.PARONYCHIA
[Acute/Chronic] paronychia of [digit]. [Abscess present—I&D performed / No abscess]. Plan: [warm soaks / antibiotics / antifungal cream]. [For chronic: Discussed importance of keeping nails dry and avoiding wet work.] Follow-up in [timeframe].
.MELANONYCHIA
Longitudinal melanonychia of [digit]. [Concerning features present: (list) / No concerning features—benign-appearing in patient with dark skin]. Plan: [Urgent derm referral for nail matrix biopsy / Observation with serial photography]. Discussed importance of monitoring for changes. [Follow-up in 6 months with photos / Derm appointment scheduled].