Indication onychomycosis confirmation before systemic therapy
Indication suspected resistance or outbreak
Safety monitoring for systemic therapy
Baseline risk stratification labs
Hepatic enzymes
Indication planned oral terbinafine or itraconazole
Higher priority with known liver disease
Complete blood count
Indication prolonged systemic therapy
Indication immunocompromised host
Pregnancy test when relevant
Indication systemic azole consideration
Indication uncertain pregnancy status
Co-infection and host factor labs
Associated testing
Glucose or HbA1c pathway when indicated
Recurrent tinea pedis or onychomycosis
Poor wound healing
HIV testing pathway when indicated
Extensive or refractory dermatophytosis
Opportunistic infection concern
Diagnostic Tests
Scoring Systems
Severity stratification tools
Onychomycosis Severity Index
Inputs
Area of nail involvement
Proximity to nail matrix
Dermatophytoma presence
Subungual hyperkeratosis thickness greater than 2 mm
Interpretation bands
Mild score 1 to 5
Moderate score 6 to 15
Severe score 16 to 35
Clinical pattern classification for tinea pedis
Interdigital type
Maceration and fissuring
Hyperkeratotic moccasin type
Diffuse plantar scaling
Vesiculobullous type
Vesicles on arch or plantar surface
MRI
Advanced imaging indications
Suspected osteomyelitis in diabetic foot context
Persistent pain and swelling
Nonhealing ulcer with concomitant tinea pedis
Deep space infection concern
Severe pain
Systemic toxicity
MRI limitations for superficial tinea
Not a routine test for dermatophyte diagnosis
Use only for complications
CT
CT indications
Orbital or facial complication concern
Periorbital swelling with pain
Vision symptoms
Necrotizing infection concern
Gas in soft tissues
Fascial thickening
CT limitations for superficial tinea
Not a diagnostic test for dermatophytosis
Use only for alternate diagnosis or complication
Ultrasound
Ultrasound applications
Abscess evaluation in superinfected lesions
Fluctuant or tender mass
Drainable collection identification
Lymph node assessment in inflammatory scalp disease
Reactive adenopathy support
Ultrasound limitations for superficial tinea
Does not confirm dermatophyte etiology
Adjunct for complications only
Disposition
Level of care decisions
Outpatient management default
Uncomplicated localized tinea corporis cruris pedis
Topical therapy plan
Hygiene and transmission counseling
Stable tinea capitis without systemic illness
Systemic therapy plan
Close follow-up plan
Admission or observation considerations
Extensive skin involvement with systemic symptoms
Secondary bacterial infection pathway
Immunocompromised with widespread disease
Rapid progression risk
Specialist involvement threshold lower
Severe cellulitis overlying tinea pedis
IV antibiotics pathway
Limb threat risk
Follow-up and referral
Specialty follow-up triggers
Refractory disease after appropriate course
Fungal culture and speciation
Resistance concern workup
Kerion
Dermatology or pediatrics follow-up within 24 to 72 hours
Onychomycosis with systemic therapy plan
Primary care or dermatology follow-up for monitoring
Diagnostic uncertainty
Dermatology evaluation
Biopsy consideration if nonfungal etiologies suspected
Treatment
Nonpharmacologic and infection control
Supportive measures
Skin care
Keep area dry
Loose breathable clothing
Fomite control
Daily sock change
Hot wash towels and bedding
Do not share razors hats hairbrushes
Footwear interventions
Dry shoes fully between uses
Antifungal powder in shoes
Contact management
Treat symptomatic household contacts
Veterinary evaluation for symptomatic pets
Topical therapy
Topical antifungal strategy
Allylamines
Terbinafine 1 percent cream
Frequency once daily
Duration 1 to 2 weeks
Naftifine 1 percent cream
Frequency once daily
Duration 2 to 4 weeks
Benzylamines
Butenafine 1 percent cream
Frequency once daily
Duration 2 weeks
Azoles
Clotrimazole 1 percent cream
Frequency twice daily
Duration 2 to 4 weeks
Miconazole 2 percent cream
Frequency twice daily
Duration 2 to 4 weeks
Ketoconazole 2 percent cream
Frequency once daily
Duration 2 to 4 weeks
Hydroxypyridones
Ciclopirox 0.77 percent cream
Frequency twice daily
Duration 2 to 4 weeks
Application principles
Continue 1 week after clinical clearing
Relapse reduction rationale
Cover lesion plus 2 cm margin
Edge hyphae burden rationale
Avoid topical corticosteroid monotherapy
Tinea incognito risk
Systemic therapy
Indications for oral agents
Tinea capitis
Topicals insufficient due to follicular involvement
Tinea barbae
Follicular depth involvement
Extensive tinea corporis or cruris
Multiple sites or large surface area
Refractory disease after adherent topical course
Culture and speciation pathway
Onychomycosis with functional or pain burden
Confirmation testing preferred before systemic therapy
Terbinafine oral
Adult dermatophyte skin infection dosing
Terbinafine 250 mg daily
Duration tinea corporis 2 to 4 weeks
Duration tinea cruris 2 to 4 weeks
Duration tinea pedis 2 to 6 weeks
Adult onychomycosis dosing
Terbinafine 250 mg daily
Duration fingernails 6 weeks
Duration toenails 12 weeks
Pediatric tinea capitis dosing
Weight-based regimen per pediatric references
Approximate range 5 to 8 mg per kg per day
Typical duration 4 to 6 weeks
Safety considerations
Hepatotoxicity risk
Baseline hepatic enzymes when prolonged course planned
Drug interactions via CYP2D6 inhibition
Tricyclic antidepressants interaction potential
Beta blocker interaction potential
Griseofulvin oral
Primary role tinea capitis
Microsize dosing
20 to 25 mg per kg per day
Duration 6 to 8 weeks
Ultramicrosize dosing
10 to 15 mg per kg per day
Duration 6 to 8 weeks
Administration considerations
Take with fatty meal
Absorption improvement
Safety considerations
Pregnancy contraindication
Teratogenicity concern
Azole systemic alternatives
Itraconazole oral
Pulse or continuous regimens per specialist pathway
Drug interaction burden
Heart failure contraindication concern
Resistant dermatophytosis option in consultation pathway
Suspected terbinafine resistance
Fluconazole oral
Alternative tinea capitis option
Weekly or daily regimens per specialist pathway
Adjunct scalp measures in tinea capitis
Selenium sulfide shampoo 2.5 percent
Frequency 2 to 3 times weekly
Duration first 2 weeks of systemic therapy
Ketoconazole shampoo 2 percent
Frequency 2 to 3 times weekly
Transmission reduction rationale
Nail-specific therapy
Topical nail options
Efinaconazole 10 percent solution
Daily application
Prolonged course months scale
Tavaborole 5 percent solution
Daily application
Prolonged course months scale
Ciclopirox 8 percent lacquer
Daily application with weekly debridement
Lower cure rates relative to oral therapy
Debridement strategy
Mechanical trimming
Reduced fungal burden
Improved topical penetration
Special Populations
Pregnancy
Pregnancy considerations
Topical therapy preference
Minimal systemic absorption
First-line for localized disease
Systemic azole caution
Teratogenicity concerns with high-dose or prolonged exposure
Specialist involvement for systemic need
Griseofulvin avoidance
Pregnancy contraindication
Breastfeeding considerations
Minimize systemic exposure when possible
Shared decision-making for oral agents
Geriatric
Older adult considerations
Polypharmacy interaction risk
Terbinafine CYP2D6 interaction potential
Itraconazole interaction burden
Hepatic reserve considerations
Baseline hepatic enzymes when systemic therapy planned
Peripheral vascular disease and diabetes overlap
Foot skin breakdown risk
Secondary bacterial infection risk
Pediatrics
Pediatric considerations
Tinea capitis prevalence emphasis
Systemic therapy required
School and household transmission counseling
Weight-based dosing necessity
Terbinafine weight-based regimen
Griseofulvin weight-based regimen
Kerion management pathway
Urgent follow-up
Secondary bacterial infection assessment
Background
Epidemiology
Population patterns
Common superficial fungal infection group
High household transmission potential
Tinea pedis and onychomycosis association
Shared reservoir concept
Tinea capitis pediatric predominance
School and daycare clustering
Emerging resistant dermatophytosis
Increasing reports of severe atypical cases
Pathophysiology
Dermatophyte biology
Keratinophilic fungi
Stratum corneum invasion
Hair shaft invasion in capitis and barbae
Nail plate invasion in onychomycosis
Inflammatory host response variation
Kerion as intense inflammatory reaction
Steroid modification
Altered morphology with reduced scale
Therapeutic Considerations
Treatment principles
Site penetration dictates therapy
Hair and nails require systemic or prolonged targeted therapy
Duration depends on keratin turnover
Nails require weeks to months courses
Transmission prevention reduces recurrence
Fomite decontamination
Treat foot reservoir to protect nails
Resistant dermatophyte considerations
Culture and susceptibility when refractory
Itraconazole use in resistant cases in consultation pathway
Evidence framing for common practices
Topicals for 2 to 4 weeks typical for skin tinea patterns
Terbinafine oral 250 mg daily typical for adult skin tinea 2 to 6 weeks
Patient Discharge Instructions
Copy discharge instructions
Discharge packet
Diagnosis explanation
Superficial fungal infection of skin hair or nails
Contagious through direct contact and shared items
Medication use
Apply topical antifungal exactly as directed
Continue for full recommended duration even if better
Apply beyond visible rash edge
Hygiene and prevention
Keep area clean and dry
Change socks daily
Do not share towels clothing hats hairbrushes razors
Wash towels and bedding in hot water
Wear sandals in shared showers
Treat athlete foot promptly to prevent nail infection
Household guidance
Check household members for similar rash
Pets with hair loss need veterinary assessment
Return to care urgently
Fever
Rapidly spreading redness or severe pain
Pus drainage
Facial or eye involvement
Scalp swelling or painful boggy area
No improvement after 2 weeks of correct use
Follow-up plan
Primary care or dermatology if persistent or recurrent
Blood test monitoring if on oral antifungals when advised
References
Guidelines and evidence sources
Reference set
CDC ringworm treatment guidance
Topical antifungals typically 2 to 4 weeks for skin tinea
CDC clinician brief on emerging and resistant dermatophytosis
Resistant strains reported
Species identification and susceptibility testing for suspected resistance
AAFP diagnosis and management of tinea infections
KOH or culture when appearance atypical
Systemic therapy for tinea capitis
Carney Onychomycosis Severity Index consensus system
Severity score bands 1 to 5 mild
Severity score bands 6 to 15 moderate
Severity score bands 16 to 35 severe
StatPearls tinea corporis review
Terbinafine 250 mg daily 2 to 4 weeks for tinea corporis
StatPearls tinea capitis review
Systemic therapy requirement
Typical treatment duration 4 to 8 weeks
Mayo Clinic terbinafine dosing monograph
Adult tinea skin dosing ranges
Adult onychomycosis duration ranges
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.