A fungal nail infection, medically referred to as onychomycosis, is a chronic infection of the fingernails or toenails caused by fungi. These organisms invade the nail plate, the nail bed, or both, leading to progressive changes in nail color, thickness, and structure. Onychomycosis is one of the most common nail disorders worldwide and affects a significant proportion of adults.
Why Does Onychomycosis Occur?
Toenails are affected more often than fingernails because they are frequently enclosed in shoes, where warmth and moisture create an environment favorable for fungal growth. The most common causative organisms are dermatophytes, especially Trichophyton rubrum. Yeasts and non-dermatophyte molds may also cause infection, particularly in certain climates or in people with underlying health conditions.
Onychomycosis develops when fungi gain access to the nail unit and successfully colonize keratin-rich tissue. Keratin, the primary protein in nails, serves as a nutrient source for many fungal species. Once established, fungi grow slowly but persistently, making spontaneous resolution uncommon.
Several factors increase susceptibility. Advancing age is associated with slower nail growth and reduced peripheral circulation. Repeated nail trauma, tight footwear, excessive sweating, and exposure to communal wet areas facilitate fungal entry. Medical conditions such as diabetes, peripheral vascular disease, and immune suppression further increase risk by impairing local defense mechanisms.
What Symptoms Indicate a Fungal Nail Infection?
Fungal nail infections often begin subtly and may remain unnoticed for months or years. Early signs usually involve discoloration of the nail, which may appear white, yellow, or brown. As the infection progresses, the nail often becomes thickened, brittle, and difficult to trim.
In more advanced cases, the nail surface becomes irregular, debris accumulates beneath the nail plate, and partial separation of the nail from the nail bed may occur. Some individuals experience discomfort, pressure, or pain, particularly when wearing shoes. Although inflammation is usually mild, secondary bacterial infection can develop in vulnerable individuals.
How Is Onychomycosis Diagnosed?
Clinical appearance alone is not sufficient to diagnose onychomycosis because several non-fungal conditions can mimic its presentation. Therefore, laboratory confirmation is recommended before initiating treatment, especially systemic therapy.
Diagnosis typically involves obtaining nail clippings or subungual debris for microscopic examination, fungal culture, or histopathologic analysis. Microscopy allows rapid detection of fungal elements, while culture identifies the specific organism. Histologic staining techniques can improve diagnostic sensitivity.
How Can UV Dermoscopy Help in Suspected Fungal Nail Infection?
Based on polarized, non-polarized, and amber polarized modes, the IBOOLO DE-4100 PRO also adds a UV light function, which can be used to observe fungal fluorescence reactions on the skin.
Unde polarized light, fungal nail infections often show specific features such as:
•Irregular longitudinal streaks
•Jagged proximal edges of discoloration
•White or yellow “spike-like” patterns extending from the distal nail
Some fungi and fungal by-products may produce fluorescence when exposed to UV light. Under UV dermoscopy, clinicians may observe:
•Pale blue, greenish, or yellow fluorescence in affected nail areas
•Contrast between infected and normal nail tissue
Clinicians can use UV light to see if the "glowing" areas are receding during a course of antifungal treatment, providing a more objective measure of progress than visual inspection alone. And it is important to note that not all nail fungi fluoresce. The most common cause of onychomycosis, Trichophyton rubrum, often does not show strong natural fluorescence. In these cases, the dermatoscope is most effective when used in its polarized white light mode.
What Treatment Options Exist for Onychomycosis?
Treating fungal nail infections can be challenging due to the protective nature of the nail plate and the slow growth of nails. Treatment aims to eliminate the fungus, restore nail appearance, and prevent recurrence.
Topical antifungal treatments are applied directly to the nail surface and are generally recommended for mild or early infections. Their effectiveness is limited by poor penetration through the nail plate, and treatment often requires prolonged use.
Oral antifungal medications are commonly used for moderate to severe infections. These medications reach the nail through the bloodstream and generally produce higher cure rates. Treatment duration varies depending on the nail involved and the severity of infection. Because nails grow slowly, visible improvement may take several months after therapy is completed.
In selected cases, mechanical debridement or partial nail removal may be used to reduce fungal load or improve access of antifungal agents to the infected tissue. Adjunctive measures, such as regular nail thinning and maintaining dry conditions, can enhance treatment effectiveness.
Despite appropriate therapy, fungal nail infections may recur, highlighting the importance of ongoing preventive care.
Can Onychomycosis Be Prevented?
Although complete avoidance of fungal exposure is unrealistic, preventive measures can significantly reduce the risk of infection. Maintaining clean and dry nails is fundamental, as moisture promotes fungal growth.
Wearing breathable footwear, changing socks regularly, and avoiding prolonged use of damp shoes are effective strategies. Protective footwear in communal showers and swimming facilities limits exposure. Treating athlete’s foot promptly and avoiding the sharing of nail care tools further reduces transmission.