Overview

A common nail infection is nail fungus. Beneath the tip of your fingernail or toenail, it first appears as a white or yellow-brown patch. The nail may become thicker, disintegrate at the edge, and change colour as the fungus infection spreads. Numerous nails may be impacted by nail fungus.¹ If your nail is thicker than normal, brittle, or discoloured, you might have a fungal nail infection. Although these infections are not life-threatening, they can be difficult to cure.²

The most prevalent nail fungus, tinea unguium, is caused by a form of mould known as a dermatophyte. Although it can also damage your fingernails, tinea unguium most commonly affects your toenails. The disorder is also known as onychomycosis.³ Many people put off getting help because they think the issue will go away on its own. Untreated toenail fungus, however, can result in serious nail destruction, ongoing discomfort, and even secondary infections that spread outside of the toes. Untreated toenail fungus is considerably more dangerous for those with diabetes, cardiovascular diseases, or compromised immune systems.

For instance, people with diabetes may have infections or foot ulcers that, if untreated, can result in severe consequences including cellulitis or, in the worst situations, amputation. Fungal infections can also spread to other areas of the body, such as the hands, groin, and skin, which can worsen discomfort and pose health hazards.

Causes and risk factors

Tinea unguium is caused by a dermatophyte, a form of mould. Fungal germs, known as dermatophytes, are too small to be seen with the human eye. The protein keratin, which is present in your fingernails and toenails, is what they eat. Keratin hardens nails. Dermatophytes cause ninety per cent of fungal infections of the toenails. However, your toenails can also become infected by different kinds of fungi. Indeed, tinea unguium is one of the several infectious toenail fungus.

Direct touch can transfer the fungus to another person. Touching an infected surface might also result in toenail fungus.³ The most frequent cause of fungal nail infections is anthropophilic fungi, known as dermatophytes. Trichophyton, Epidermophyton, and Microsporum, especially, T rubrum, T mentagrophytes var interdigitale, and E floccosum are usually implicated. It is possible to isolate more fungi, moulds, or yeasts, including Candida albicans, Aspergillus, Fusarium, and Scopulariopsis brevicaulis. Today, T rubrum is thought to be the most frequent cause of onychomycosis globally.⁴

Pool decks, public baths, and hotel carpets can all harbour pathogenic microorganisms. Onychomycosis is typically preceded by an undetectable, dry hyperkeratotic tinea pedis. The hyponychial seal is compromised and broken over time by the wet, humid, and dark conditions of shoes as well as microtraumatic pressure on the nail unit, which permits the dermatophyte to enter the nail bed. Fingernails are compromised by frequent exposure to water during damp work. The keratin of dead corneocytes in the skin, hair, and nails is the only food source for dermatophytes.⁵ 

Pathophysiology

The nail bed is the main source of infection; it starts as an acute infection with low-grade inflammation and develops into a chronic phase that includes total dystrophic onychomycosis. A dense inflammatory infiltration forms, as is the case with most infections. The intact nail matrix is eventually infected by onychomycosis as well. As the nail bed thickens and becomes hyperkeratotic to remove the fungal infection, onychomycosis causes secondary damage to the nail matrix. Additionally, the dermatophyte infiltrates the nail plate on top, gradually causing it to separate and deform (White Superficial Onychomycosis).⁵

Eventually, the nail plate becomes raised and misplaced as the infection enters the complete dystrophic clinical stage of onychomycosis (Onychomycosis Nail Changes). At this chronic stage of the infection, there are substantial volumes of compact hyperkeratosis, hypergranulosis, acanthosis, and papillomatosis with scant perivascular infiltrate. Subungual seromas and dermatophytosis may develop. Researchers discovered that onychomycosis patients had elevated blood and nail bed levels of the cytokines interleukin-6 and interleukin-10-positive cells. In the bed and plate of mycotic nails, there may be many fibres that carry human beta defensin-2.⁵

Histologically, spongiosis, acanthosis, papillomatosis with oedema, and hyperkeratosis are the symptoms of an acute onychomycosis lesion. Compact hyperkeratosis, hypergranulosis, acanthosis, and papillomatosis are prevalent in the chronic stage of the illness, together with a sparse perivascular infiltration. Subungual seromas and dermatophytosis might happen.⁵

Progression and complications of untreated toenail fungus

Fungal spread to other body parts

One or more of the following are signs of nail fungus: more rigid, discoloured, fragile, crumbly, tattered, distorted, nails are not attached to the nail bed. Although it is more prevalent in toenails, smelly nail fungus can also infect fingernails.¹ Certain dermatophyte fungus can readily infect your skin. (Keratin is also found in your skin and scalp.) When dermatophyte fungus damages your skin, it is called ringworm. Toenail fungus could spread to new toenails, Athlete's foot which is the skin between your toes, groin region (also known as jock itch) and scalp.³

Complications in aigh-risk individuals

It is more common in men than in women. Additionally, your chances improve with age. Individuals who smoke or have family members with diabetes, athlete's foot, or weakened immune systems are also more vulnerable. Your risk of developing toenail fungus increases if you have a history of toenail injuries or spend a lot of your time in the water.⁶ Anyone can get a fungal nail infection, which is highly contagious. However, they are more common in elderly people; if you are over 60, you have a higher chance of developing fungal nails.

Psychosocial impact

In normally healthy individuals, onychomycosis does not cause significant problems. But according to the Achilles experiment, which involved 846 individuals with fungal toenail infections, many of them complain of pain (33%), difficulty walking (51%), or difficulty doing their jobs or other activities (13%). Severe nail dystrophy and distortion can injure the surrounding skin and result in a subsequent bacterial infection. This infection has the potential to spread among immunocompromised individuals. Onychomycosis-specific quality-of-life metrics have been created. According to studies employing these markers, onychomycosis has detrimental physical and psychological impacts.⁴

Treatment and prevention

Systemic antifungals are the best therapies for onychomycosis. In moderate to severe disease, oral antifungal medication should also be considered due to the increased risk of subungual ulcers, particularly in patients with diabetes mellitus. Compared to systemic medication alone, combination therapy using topical medications, frequent trimming, or chemical nail avulsion may yield better outcomes. For patients who would rather not take systemic antifungals, the more recent topical antifungal treatments have better cure rates for mild to moderate cases. According to meta-analyses, fluconazole is 48% effective, itraconazole pulse dosage is 63%, and terbinafine has a 76% mycological cure rate. On the other hand, the mycological cure rates for topical therapy are 36% for ciclopirox or tavaborole and 55% for efinaconazole. For systemic terbinafine, the full cure rate is 38%.⁵

Although oral medication is the most effective treatment for severe onychomycosis, certain individuals should not receive it due to medical reasons. Furthermore, a non-systemic treatment is strongly preferred by many patients. If topical medication has higher efficacy rates, it is a helpful solution to the issue. The abundance of prescription and over-the-counter treatments suggests that there are no good topical options. Oral antifungals may also be incompatible with other drugs. Monitoring is necessary because terbinafine may change how many medications are metabolised. Terbinafine is safe to use in both youngsters and the elderly.⁵

Summary

Onychomycosis, or toenail fungus, is a common but sometimes ignored illness that, if not addressed, can have serious consequences. Although it might seem like a small cosmetic problem at first, as it worsens, it can lead to severe discomfort, nail deformation, and even dangerous secondary infections. Serious problems, such as foot ulcers, cellulitis, and in severe cases, amputation, are more likely to occur in those with underlying medical disorders such as diabetes, cardiovascular diseases, or weakened immune systems. Early detection and treatment are crucial since fungal infections are tenacious and seldom go away on their own.

Untreated toenail fungus can have significant psychological repercussions in addition to its medical ones. Many affected people feel embarrassed, which lowers their confidence and makes them avoid social situations. Those who have thick, discoloured, and brittle nails may be deterred from swimming or wearing open-toed shoes due to cosmetic concerns. Fungal nail infections are more than simply a surface-level issue because of the substantial impact they can have on the quality of life due to the emotional distress and self-consciousness they cause.

Fortunately, with the right treatments, toenail fungus is very treatable. The infection can be successfully eradicated with a mix of topical therapies, systemic antifungal drugs, and good foot cleanliness. However, as severe cases necessitate protracted therapy and may not always achieve full resolution, early intervention is crucial to the outcome of treatment. The risk of infection can be significantly decreased by taking preventive steps, such as keeping your feet clean, avoiding wet areas, wearing breathable shoes, and keeping your nails clipped.

In summary, toenail fungus may initially appear to be a small problem, but neglecting it can have detrimental effects on one's health. Healthy nails and general well-being can be ensured by seeking prompt medical attention, following treatment instructions, and engaging in preventive care. To avoid difficulties and preserve a high quality of life, proactive foot care is crucial, particularly for high-risk patients.