Onychomycosis: Causes, Symptoms, Diagnosis, and Treatment Options

Introduction

Onychomycosis is a common fungal infection that affects the nails, most frequently the toenails. It occurs when dermatophytes, yeasts, or non-dermatophyte molds invade the nail plate and nail bed, leading to discoloration, thickening, and structural damage. Although not usually life-threatening, onychomycosis can significantly impact comfort, appearance, and quality of life if left untreated.

Causes of Onychomycosis

Onychomycosis is primarily caused by fungal organisms, especially dermatophytes such as Trichophyton rubrum. These fungi thrive in warm, moist environments, making public showers, swimming pools, and locker rooms common sources of infection.

Several risk factors increase the likelihood of developing the condition:

Poor foot hygiene

Wearing tight or non-breathable footwear

Excessive sweating (hyperhidrosis)

Nail trauma or injury

Diabetes or weakened immune system

Older age

Once the fungus enters through small cracks in the nail or surrounding skin, it gradually spreads, leading to infection.

Symptoms of Onychomycosis

The symptoms of onychomycosis typically develop slowly and may worsen over time. Common signs include:

Yellow, white, or brown discoloration of the nail

Thickened or brittle nail structure

Distorted nail shape

Crumbling edges of the nail

Separation of the nail from the nail bed (onycholysis)

Foul odor in advanced cases

In some cases, the infection may spread to other nails if not treated promptly.

Types of Onychomycosis

There are several clinical types of nail fungal infections:

Distal subungual onychomycosis: The most common type, starting at the nail tip and spreading inward

White superficial onychomycosis: Appears as white patches on the nail surface

Proximal subungual onychomycosis: Begins near the cuticle and is often associated with immune suppression

Candida onychomycosis: More common in fingernails and often linked to chronic wet exposure

Diagnosis

Diagnosis of onychomycosis involves clinical examination and laboratory testing. A healthcare provider may:

Examine nail appearance and symptoms

Collect nail clippings or scrapings

Perform microscopy (KOH test)

Conduct fungal culture or PCR testing for confirmation

Accurate diagnosis is important because other conditions, such as psoriasis or trauma, can mimic fungal nail infections.

Treatment Options

Treatment depends on severity and type of infection. Common approaches include:

Topical Treatments

Antifungal creams, lacquers, or solutions are used for mild cases. These are applied directly to the nail but may require long-term use.

Oral Antifungal Medications

Drugs such as terbinafine or itraconazole are often prescribed for moderate to severe infections. These medications work from within the body to eliminate the fungus.

Nail Removal

In severe or resistant cases, partial or complete removal of the infected nail may be recommended.