Overview

Onychomycosis, commonly known as nail fungus or tinea unguium, is a persistent fungal infection that affects the nail bed, matrix, or plate. This condition is one of the most common nail disorders, accounting for up to 50% of all nail abnormalities. While it can affect both fingernails and toenails, toenail infections are significantly more common due to the warm, moist environment created by shoes and socks.

The infection typically begins as a white or yellow spot under the tip of the nail. As the fungal infection spreads deeper, it can cause the nail to discolor, thicken, and crumble at the edge. Multiple nails can be affected simultaneously, and the condition can spread from one nail to another. Without treatment, onychomycosis can persist indefinitely and may lead to permanent nail damage.

While onychomycosis is not typically dangerous in healthy individuals, it can cause significant cosmetic concerns and, in some cases, pain and difficulty with daily activities. In people with compromised immune systems or diabetes, nail fungus can lead to more serious complications, including secondary bacterial infections and cellulitis. The condition affects people of all ages but becomes more common with advancing age, affecting up to 20% of people over 60 years old.

Symptoms

Causes

Onychomycosis is caused by various types of fungi that invade and grow in the nail unit. Understanding these causative organisms helps guide treatment decisions and prevention strategies.

Primary Causative Organisms

• Dermatophytes (80-90% of cases):
  • Trichophyton rubrum (most common)
  • Trichophyton mentagrophytes
  • Epidermophyton floccosum
• Non-dermatophyte molds (2-10%):
  • Scopulariopsis brevicaulis
  • Aspergillus species
  • Fusarium species
  • Acremonium species
• Yeasts (5-10%):
  • Candida albicans
  • Candida parapsilosis

How Infection Occurs

Fungal nail infections develop through several mechanisms:

• Direct invasion: Fungi enter through small cuts in the skin or separations between the nail and nail bed
• Spread from skin: Extension from athlete's foot or other fungal skin infections
• Environmental exposure: Contact with contaminated surfaces in public areas
• Person-to-person transmission: Sharing nail care tools or footwear
• Autoinoculation: Spreading from one infected nail to others

Contributing Factors

• Warm, moist environments that promote fungal growth
• Nail trauma creating entry points for fungi
• Poor peripheral circulation reducing natural defenses
• Compromised immune system
• Genetic predisposition to fungal infections
• Occlusive footwear trapping moisture

Risk Factors

Several factors increase the likelihood of developing onychomycosis:

Diagnosis

Accurate diagnosis of onychomycosis is essential because many nail conditions can mimic fungal infections. Only about 50% of nail dystrophies are actually caused by fungi.

Clinical Examination

• Visual inspection: Assessment of nail appearance, color, thickness, and texture
• Dermoscopy: Magnified examination of nail structures
• Pattern recognition: Identifying specific patterns of fungal invasion
• Affected nail count: Documenting number and location of affected nails

Laboratory Tests

Differential Diagnosis

Conditions that can mimic onychomycosis include:

• Psoriatic nail disease
• Lichen planus
• Traumatic nail dystrophy
• Yellow nail syndrome
• Nail changes from systemic diseases
• Age-related nail changes

Treatment Options

Treatment of onychomycosis requires patience and persistence, as nails grow slowly and complete cure can take months. The choice of treatment depends on the severity, number of affected nails, and patient factors.

Oral Antifungal Medications

Most effective for moderate to severe infections:

• Terbinafine (Lamisil):
  • First-line treatment for dermatophyte infections
  • 250mg daily for 6 weeks (fingernails) or 12 weeks (toenails)
  • Success rate: 70-80%
• Itraconazole (Sporanox):
  • Effective against dermatophytes and some yeasts
  • Pulse therapy: 200mg twice daily for 1 week per month
  • Continuous therapy: 200mg daily for 3 months
• Fluconazole (Diflucan):
  • Weekly dosing option
  • 150-300mg once weekly for 6-12 months

Topical Treatments

Non-Pharmacological Treatments

• Laser therapy: Nd:YAG laser treatment to heat and destroy fungal elements
• Photodynamic therapy: Light-activated treatment
• Surgical removal: For severe, painful, or non-responsive cases
• Chemical avulsion: Using urea compounds to dissolve infected nail
• Regular debridement: Professional nail trimming and thinning

Monitoring and Follow-up

• Monthly clinical assessment during treatment
• Laboratory monitoring for oral medications (liver function)
• Mycological cure confirmation after treatment
• Long-term follow-up to detect recurrence
• Patient education on prevention

Prevention

Preventing onychomycosis involves maintaining good foot and nail hygiene and avoiding environments where fungi thrive:

Personal Hygiene

• Keep feet clean and dry, especially between toes
• Change socks daily or when damp
• Trim nails straight across and file down thickened areas
• Don't share nail clippers or files
• Disinfect nail tools regularly
• Avoid picking at skin around nails

Footwear and Environment

• Wear breathable footwear made of natural materials
• Alternate shoes to allow them to dry completely
• Use antifungal powder in shoes
• Wear shower shoes in public areas
• Choose moisture-wicking socks
• Avoid walking barefoot in public spaces

Risk Reduction Strategies

• Treat athlete's foot promptly to prevent spread
• Control underlying conditions like diabetes
• Inspect feet and nails regularly
• Choose reputable nail salons with good hygiene
• Bring your own nail care tools to salons
• Apply antifungal products preventively if high risk

Post-Treatment Prevention

• Continue topical antifungals as maintenance
• Replace old footwear that may harbor fungi
• Maintain vigilant foot hygiene
• Regular follow-up examinations
• Address any new nail changes promptly

When to See a Doctor

While nail fungus isn't usually an emergency, certain situations warrant medical attention:

Related Conditions

References

1. Gupta AK, et al. (2023). "Onychomycosis: Strategies to Improve Efficacy and Reduce Recurrence." Journal of the American Academy of Dermatology.
2. Lipner SR, Scher RK. (2023). "Onychomycosis: Clinical Overview and Diagnosis." Journal of the American Academy of Dermatology.
3. Elewski BE, et al. (2023). "Onychomycosis: Pathogenesis, Diagnosis, and Management." Clinical Microbiology Reviews.
4. American Academy of Dermatology. (2023). "Guidelines for the Management of Onychomycosis."
5. Piraccini BM, Alessandrini A. (2023). "Onychomycosis: A Review." Journal of Fungi.
6. Centers for Disease Control and Prevention. (2023). "Fungal Nail Infections." CDC Health Information.