Definition

Onychomycosis, also referred to as tinea unguium, is a fungal infection of the nail. It can affect both toenails and fingernails, although it is more frequently seen in toenails. This condition can cause nails to become discolored, thickened, and more susceptible to cracking or breaking. The infection typically occurs when fungi enter through cracks or small injuries in the toenails, though the progression of fungal nail infections is slow, making changes in nail shape or appearance hard to notice initially. Onychomycosis can affect multiple nails simultaneously.

The prevalence of onychomycosis is common and tends to increase with age. Statistics suggest that 1 in 10 people may develop this infection, with the figure rising to 1 in 2 for individuals over 70. However, it is rarely observed in children.

Causes

Onychomycosis is caused by various fungal organisms that thrive in the environment, with dermatophytes being the most common culprits. Dermatophytes are microscopic fungi that feed on keratin, a protein found in nails that strengthens them. Common dermatophyte species include Epidermophyton, Microsporum, and Trichophyton. Yeasts, such as Candida albicans, account for 8% of fungal nail infections, while non-dermatophyte fungi cause approximately 2% of cases.

Although onychomycosis can occur at any age, it is more prevalent among older adults. As nails age, they may become dry and brittle, leading to cracks that enable fungi to penetrate and cause infection. The incubation period for fungal nail infections ranges from 3 to 6 days.

Onychomycosis is also highly contagious, allowing the fungus to spread through direct contact or by touching contaminated surfaces. The fungi responsible for this infection thrive in warm, moist, and dark environments, which is why many infections occur through:

• Walking around the edges of swimming pools
• Using public locker rooms or showers
• Walking barefoot in public areas

Risk Factor

Several factors can increase the likelihood of developing onychomycosis, including:

• Being over 60 years old, as reduced blood circulation, long-term exposure to fungi, and slower nail growth accompany aging.
• Excessive sweating (hyperhidrosis).
• A history of athlete's foot (fungal infection of the toes).
• Walking barefoot in damp public places, such as swimming pools, gyms, or public showers.
• Nail or surrounding skin injuries, or skin conditions like psoriasis.
• Having diabetes, poor circulation, or a compromised immune system (as in autoimmune disorders or HIV).
• Wearing tight shoes that fully cover the toes.
• Direct or indirect contact with an infected individual (e.g., sharing shoes or socks).
• Wearing fake nails.
• Having a family member prone to fungal nail infections.

Symptoms

Onychomycosis can affect both toenails and fingernails. Common symptoms include:

• Nails are becoming thickened.
• Nail discoloration, turning white, brown, or yellow.
• Brittle or cracked nails.
• Changes in nail shape.
• Nails appearing chalky or cloudy in certain areas.
• A slight foul odor from the nails.
• Generally, no pain is present.
• Nails separating from the nail bed, creating a gap between the nail and the skin underneath.

Diagnosis

To diagnose onychomycosis, the doctor will begin by asking a series of questions, including:

• What symptoms are you experiencing?
• When did the symptoms first appear?
• Which parts of your nails are affected?
• Have you had previous nail infections?
• Have you undergone any treatments in the past?
• What is your complete medical history, including any other illnesses you've had?

Following the interview, a physical examination will be conducted. The doctor will closely inspect the affected nails. Although the diagnosis can often be made from the interview and the appearance of the nails, a diagnostic test is commonly recommended to confirm the findings.

The diagnostic test usually involves scraping a small portion of the nail and the tissue underneath to use as a sample for microscopic examination. The sample is often mixed with a KOH (Potassium Hydroxide) solution to better visualize the fungus under a microscope. If no fungus is detected in the scraping, a fungal culture test might be recommended, which involves growing the sample in a special medium.

Management

Onychomycosis can be difficult to treat and often does not resolve without antifungal therapy. Treatment may be necessary for several months, and the condition can often recur. Several treatment options are available:

1. Antifungal Medication

Doctors may prescribe antifungal medications in topical or oral forms. Topical treatments are applied directly to the nail but are most effective when combined with oral antifungal medications.
Oral medications such as Terbinafine, Itraconazole, and Fluconazole are commonly prescribed. These medications are taken daily for several months or longer. Blood tests may be required to monitor potential side effects, particularly liver function, as these drugs can affect the liver and interact with other medications. Regular medical supervision is necessary.

2. Laser Treatment

In this treatment, the doctor uses high-tech laser beams and special lights to target the infected nails. However, the success rate with laser treatment is lower compared to oral and topical antifungal medications, making it a secondary option.

3. Nail Removal

Temporary nail removal may be recommended so antifungal treatments can be applied directly to the infection beneath the nail. If onychomycosis does not respond to medication, or if the infection is severe and painful, permanent nail removal may be suggested.

Complications

Though fungal nail infections primarily affect the toes, they can occasionally spread to other body parts. Dermatophyte fungi, in particular, can spread to the skin, leading to the following complications:

• Infection of other toenails
• Spread to the skin between the toes
• Spread to the groin area
• Infection of the skin on the head
• Recurring fungal infections
• Permanent loss of the infected nail
• Nail discoloration
• Bacterial skin infection, such as cellulitis

Prevention

Although it's not always possible to completely prevent fungal nail infections, you can reduce the risk by taking the following steps:

• Avoid walking barefoot in public areas, such as hotel rooms, public bathrooms, locker rooms, and swimming pools.
• If a family member has onychomycosis, use a different bathroom or wear flip-flops in shared showers.
• Clean your nail clippers before each use.
• Avoid tearing or damaging your toenails.
• Follow your doctor’s foot care advice if you have diabetes.
• Keep your feet dry, and ensure they are thoroughly dried after showering.
• Soak your toenails in warm water before cutting them, or trim them after a shower.
• Wear shoes that fit properly—not too loose or tight around the toes.

When to see a doctor?

You should consult a doctor if you experience any symptoms of onychomycosis. A doctor can help diagnose the condition and provide the appropriate treatment, but be aware that treatment may take an extended period.

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