How do we determine if treatment for tinea capitis (ringworm of the scalp) is failing in a patient with no hair regrowth, despite clinical improvement and negative skin test, who is currently taking griseofulvin (antifungal medication) and using ketoconazole (antifungal medication) shampoo?

Determining Treatment Failure in Tinea Capitis

The endpoint of treatment for tinea capitis is mycological cure, not clinical improvement—therefore, you determine treatment failure by obtaining repeat fungal cultures, and if cultures remain positive despite adequate treatment duration, or if there is no clinical improvement after the standard treatment period, the treatment has failed. 1

Key Principle: Mycological Cure vs Clinical Cure

• Negative skin tests (fungal cultures) with ongoing alopecia does NOT indicate treatment failure—it indicates successful treatment with residual cosmetic effects. 1
• Hair regrowth lags significantly behind mycological clearance and can take 3+ months after fungal eradication. 1
• The absence of inflammation, redness, or scaling with negative cultures actually suggests the infection has been successfully treated. 1

Defining Treatment Failure: The Correct Criteria

Treatment failure should be assessed based on these specific parameters:

After Standard Treatment Duration:

• For griseofulvin: Reassess at 6-8 weeks of therapy 1, 2
• For terbinafine: Reassess at 2-4 weeks of therapy 1, 2

Two Scenarios Indicate Failure:

1. Clinical improvement BUT positive mycology: Continue current therapy for an additional 2-4 weeks before declaring failure 1

2. No clinical improvement AND/OR persistently positive cultures: This represents true treatment failure requiring second-line therapy 1

What to Assess at Follow-Up

Repeat mycology sampling (scalp scrapings, hair pluck, brush, or swab) is mandatory until clearance is documented: 1

• Obtain specimens at the end of standard treatment period 1
• Continue monthly sampling until mycological clearance is achieved 1
• Clinical signs alone (hair regrowth) are insufficient to determine cure 1

Common Causes of Apparent Treatment Failure

Before switching therapy, systematically evaluate these factors: 1

• Poor compliance: Most common cause, especially with longer griseofulvin courses 1
• Suboptimal drug absorption: Griseofulvin requires high-fat meals for adequate absorption 3
• Organism insensitivity: Wrong drug for the causative species (e.g., terbinafine fails against Microsporum) 1, 2
• Reinfection: Untreated household contacts serving as reservoirs, particularly with T. tonsurans 1

Critical Pitfall to Avoid

Do not confuse slow hair regrowth with treatment failure. 1

• Alopecia areata guidelines note that regrowth cannot be expected within 3 months of patch development 1
• In your patient's case: negative cultures + no inflammation + no scaling = successful mycological cure 1
• The persistent alopecia may represent:
  • Normal lag time for hair regrowth post-infection
  • Permanent scarring if there was kerion formation
  • Coincidental alopecia areata (though less likely given the clinical context)

When to Proceed to Second-Line Therapy

Only switch agents if: 1

• Cultures remain positive after extending current therapy by 2-4 weeks 1
• No clinical improvement (worsening scale, inflammation, or spread) despite adequate treatment duration 1
• Confirmed poor absorption or compliance issues that cannot be resolved 1

Second-line options include: 1, 2

• Itraconazole 5 mg/kg/day for 2-4 weeks (effective against both Trichophyton and Microsporum) 1
• Switch from terbinafine to griseofulvin for Microsporum, or vice versa for Trichophyton 1

Your Patient's Situation

Based on the clinical description (no inflammation, no redness, no scaling, negative skin test), this patient has achieved mycological cure and does NOT have treatment failure. 1 The lack of hair regrowth is expected and does not warrant escalation of antifungal therapy. Reassurance and continued observation for hair regrowth over the next several months is appropriate. 1