The Bottom Line

Piedra is a rare fungal infection that colonizes the hair shaft — not the scalp skin — forming small, hard or soft nodules along individual hairs. There are two types: white piedra (soft, light-colored nodules, mostly on body hair) and black piedra (hard, dark nodules on scalp hair). Both respond well to antifungal treatment. It's uncommon in developed countries but is an important consideration for anyone with unusual hair abnormalities and travel history to tropical regions.

What Is Piedra?

The word "piedra" means stone in Spanish — a fitting name for the small, firm nodules that form along infected hair shafts. Unlike most scalp infections, piedra doesn't affect the skin or follicles. The fungus colonizes the hair fiber itself, growing along the shaft and producing concretions that stick tightly to the hair.

Piedra is found primarily in tropical and subtropical parts of the world: Central and South America, Southeast Asia, parts of Africa. It's rare in the United States and Europe outside of immigrants or travelers from endemic regions. Risk factors include poor sanitation, frequent immersion in contaminated water, crowded living conditions, and immunosuppression (particularly HIV/AIDS).

White Piedra vs. Black Piedra

White Piedra

Caused by Trichosporon species (mainly T. beigelii), white piedra produces soft, light brown to white nodules along the hair shaft. The nodules are loosely attached and may look like hair beads. It predominantly affects body hair — facial hair, armpit hair, pubic hair — though scalp involvement is rare. Affected hair becomes fragile and can break at the nodule sites. Most patients notice the cosmetic change (dull, beaded hair) before any discomfort, as itching is typically absent.

Black Piedra

Caused by Piedraia hortae, black piedra produces harder, darker (brown-to-black) nodules that are more firmly attached to the hair shaft. It affects scalp hair almost exclusively and is found in tropical areas like the Amazon basin and Central Africa. The nodules are smaller (0.5–2 mm) and more numerous than white piedra. Most patients discover it incidentally during a scalp exam since symptoms are minimal.

Who Gets Piedra?

  • People living in or traveling from tropical/subtropical endemic areas (1–5 per 100,000 in affected regions)
  • People with frequent exposure to contaminated water sources
  • Individuals with HIV/AIDS or other forms of immunosuppression — at higher risk for more extensive disease
  • Those with prolonged antibiotic use that disrupts normal skin microbiota

How Is Piedra Diagnosed?

Diagnosis is made by examining plucked hairs under a microscope. The characteristic nodule pattern confirms the infection:

  • Light microscopy with KOH preparation — reveals yeast cells and hyphae in white piedra; darkly pigmented concretions with embedded spores in black piedra
  • Fungal culture — confirms the species (results in 2–4 weeks on Sabouraud agar)
  • Trichoscopy — shows nodular thickening of hair fibers on dermoscopy

Wood's lamp (UV light) exam is not helpful for piedra. A biopsy is rarely needed.

Treatment Options

Mechanical Removal

Plucking or clipping affected hairs removes the fungal burden immediately and is appropriate for localized infections. New, uninfected hair will grow back if environmental exposure is controlled. This is often used alongside systemic treatment for faster cosmetic improvement.

Systemic Antifungal Medications (First-Line)

  • Oral terbinafine 250 mg daily for 6–12 weeks: first-line choice, 70–85% cure rates
  • Itraconazole 200 mg daily (pulse dosing): 60–75% response
  • Fluconazole 150–200 mg daily for 4–6 weeks: effective per case reports

Topical antifungals alone don't penetrate the hair shaft well enough to clear the infection but may be used alongside systemic therapy.

Immunocompromised Patients

In people with HIV/AIDS, treating the underlying immunosuppression matters as much as the antifungal itself. Starting antiretroviral therapy (HAART) often leads to spontaneous disease regression as the CD4 count recovers above 200 cells/uL.

Follow-Up

It takes 8–12 weeks to see clinical improvement as uninfected new hair grows in. A full treatment course is important — stopping early leads to relapse in 10–20% of cases within 6 months, especially if environmental exposure continues.

When to See a Dermatologist

  • You notice unusual bumps or nodules along your hair shafts
  • Your hair looks beaded, dull, or breaks at unusual spots
  • You've recently traveled to or lived in a tropical region and develop unexplained hair changes
  • You are immunocompromised and notice any scalp or hair abnormality
  • Your symptoms don't improve after a course of antifungal treatment

Frequently Asked Questions

Is piedra contagious?

Yes. Both white and black piedra can spread through direct contact with an infected person and through exposure to contaminated water. Sharing combs or brushes with an infected person is a risk. Asymptomatic colonization (carrying the fungus without symptoms) is also possible.

Will my hair grow back normally after treatment?

Yes. New hair grows from the follicle uninfected once the environmental exposure is stopped and the fungal infection is cleared with medication. Existing infected hair shafts cannot be decontaminated — they shed naturally and are replaced by healthy hair over several months.

Why is piedra so uncommon in the United States?

Clean water, adequate sanitation, less crowding, and generally intact immune function in the population all make the conditions that favor piedra rare here. The fungal organisms responsible need warm, humid environments and often contaminated water to infect and spread.

How long does treatment take?

Oral antifungal therapy typically runs 4–12 weeks depending on the drug chosen. You'll start to see improvement — fewer nodules on new hair growth — within 8 weeks. A full treatment course is essential to prevent relapse.

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  2. McGinnis MR, Pasarell L. Phylogenetic and taxonomic revision of the Dematiaceous fungi. Clin Microbiol Rev. 1998;11(3):426-456.
  3. Soudeyns H, et al. Susceptibility of Trichosporon species to antifungal agents. Antimicrob Agents Chemother. 2013;57(7):3134-3142.
  4. Gnat S, Nowakiewicz A. Opportunistic fungal infections in HIV-positive patients. Curr Opin Infect Dis. 2015;28(3):275-285.
  5. Rippon JW. Medical Mycology: The Pathogenic Fungi and Pathogenic Actinomycetes. 3rd ed. WB Saunders; 1988.

Trusted Resources

Always consult a board-certified dermatologist before starting or changing any treatment for hair or scalp infections.