Onychomycosis: Types, Symptoms, Causes, Diagnosis, Risk Factors and Treatment

The fungal infection of the toenails or hands is caused by a fungal organism that invades the nail bed.

Fungal nail infection is also called onychomycosis and tinea unguium; in 90% of cases, it is caused by organisms called dermatophytes.

Fungal infection of the nails causes the nails of the hands or feet to harden, discolor, disfigure and split.

Adults, especially the elderly, are more likely to have onychomycosis than children.

Types of osmosis

The main subtypes of onychomycosis are the following:

  • Distal subungual lateral onychomycosis (the area under the nail).
  • White superficial onychomycosis.
  • La onicomicosis subungueal proximal.
  • Endoniax onychomycosis.
  • Candida onychomycosis

Patients with fungal nail infection may have a combination of these onychomycosis subtypes.

The term total dystrophic onychomycosis is the most advanced form of any subtype.



This disease is usually asymptomatic; sometimes, it can cause pain or discomfort.

Onychomycosis is an infection of the nails caused by a fungus.

The symptoms of the infection will vary depending on the type of fungus involved. Still, the nails thickened and flaked (subungual hyperkeratosis). The discoloration of the nail to colors such as yellow, green, brown, or black (dyschromia) and separation of the nail bed from the pin (Onycholysis) are common symptoms.

Sometimes this can be complicated in patients suffering from diabetes or immunosuppressed, with essential conditions such as cellulitis or erysipelas.


Approximately half of all nail complaints result from a fungal infection, making onychomycosis the most common nail disorder.

Onychomycosis is a disease that can affect both the nails of the hands and the feet; however, toenails are more likely to be infected.

This is not entirely clear, but the slower growth of the toenails concerning the nails of the hands can facilitate the fungi to establish and cause an infection in the toenails.

In addition, fungi generally thrive in warm, humid conditions.

Therefore, closed shoes and plastic shoes are ideal conditions for these organisms, facilitating the infection of the feet and toenails.

Walking barefoot in public areas such as changing rooms and showers of sports or recreational facilities and swimming pools also increases the risk of infection since this hot and humid environment is susceptible to fungal contamination.

The nails of the hands can also be infected, often by another type of fungus.

Often, this type of infection occurs in people whose hands have been exposed to water for long periods, for example, the dishwasher in restaurants or people in charge of tasks such as cleaning facilities.

The use of double gloves, with cotton on the inside and latex or vinyl on the outside, when in contact with water helps prevent the development of this type of infection.


The doctor will probably begin a physical examination simply by observing the nails.

The different types of onychomycosis have characteristics that suggest fungal infection in the nails and can be used to differentiate onychomycosis from other types of disease.

There are additional laboratory tests that can be used to confirm the diagnosis.

Observing the sections of the nails under the optical microscope is sometimes used to visualize directly in the tissue the fungi that cause the disease.

In this observation of the scales, potassium hydroxide (KOH) of 20 to 30% is used to eliminate the keratin.

This will allow you to visualize the fungal elements and immediately diagnose onychomycosis; you can also distinguish dermatophytes and yeasts.

To identify the causative agent, mycological cultures can be performed in appropriate media in the laboratory from samples and scraped nails to demonstrate its existence and the species of fungi responsible for the disease.

For this reason, it is sometimes necessary for the doctor to make a preliminary diagnosis based on the examination of the nails and confirm it in the laboratory using microscopy and culture techniques.

Usually, this type of laboratory test requires a few weeks before presenting the results.

Identifying dermatophytes will require a minimum of two weeks of incubation.

Suppose there is the growth of the organisms. In that case, the study of the macroscopic and microscopic aspects of the colony will allow the identification of the species that causes the fungal infection.

Risk factor’s

Not everyone has the same risk of developing fungal infections on the nails.

Studies have shown that several factors increase the risk of common infections due to onychomycosis:

The age of the patient:

The risk of developing onychomycosis increases with age.

This may be because older people have slower-growing nails, have difficulty caring for their feet and toenails, and are more likely to have other risk factors for the disease (poor peripheral blood circulation, diabetes, weakened immune status). Among others).

Deficiency in peripheral blood circulation:

People with poor peripheral blood circulation are more susceptible to infections caused by fungi.


Diabetes has several effects on the circulatory system and has increased the risk of developing onychomycosis.


Onychomycosis is more common in people with psoriasis than in those who do not.

Sports practice:

Some sports can increase exposure to pathogenic fungi and, therefore, increase the risk of fungal infection.

People who swim, for example, are more likely to have onychomycosis than those who do not.

Patients with immunodeficiency:

As with other types of infection, a weakened immune system increases the risk of developing onychomycosis.

Genetic factors:

Some people seem to be naturally more susceptible to fungal infections, such as onychomycosis.

The exact genes involved have not been identified, but some research suggests that you are more likely to develop fungal infections in the nails if you have a family history.

Other risk factors:

Other factors include:

  • Prolonged contact with water.
  • Prolonged use of plastic gloves.
  • Frequent or prolonged manipulation of sweet products (sweets, pastry).
  • Excessive use of detergents.
  • The habit of smoking.
  • Repeated microtraumas on the nails (like the practice of gardening).
  • Profession exposed (hairdresser, manicure, podiatrist).


The objective of treating onychomycosis besides the mycological cure is the recovery of the damaged nail.

The use of topical agents should be limited to cases involving less than half of the distal plate of the nail or for patients who can not tolerate systemic treatment.

The medications include ciclopirox olamine, such as:

Batrafen, Fungirox, Loprox, Penlac, and Stieprox, the topical solution of efinaconazole, amorolfine hydrochloride, bifonazole, and urea.

Topical treatments alone usually can not cure onychomycosis due to insufficient penetration into the nail plate.

It has been reported that ciclopirox and amorolfine solutions penetrate through all nail layers but have low efficacy when used as monotherapy.

They may be helpful as therapy administered in combination with oral therapy or as prophylaxis to prevent recurrence in patients cured with systemic agents.

For efinaconazole and ciclopirox, a daily application and a long duration of treatment are required (48 weeks).

Efficaconazole is indicated for onychomycosis in toenails.

Tavaborol, a toxic oxaborol antifungal (a compound containing boron), is indicated for onychomycosis of the toenails due to Trichophyton rubrum or Trichophyton mentagrophytes.

Laser treatment can be combined with topical antifungals.

In oral therapy, the new generation of oral antifungal agents (such as itraconazole and terbinafine) has replaced the older therapies in treating onychomycosis.

These therapies offer shorter treatment regimens, higher cure rates, and minor adverse effects.

Fluconazole and the new posaconazole triazole offer an alternative to itraconazole and terbinafine.

The effectiveness of the newest antifungal agents lies in their ability to penetrate the nail plate within a few days of starting therapy.

The evidence shows a better efficacy with terbinafine than with other oral agents.

Oral antifungal therapy combined with topical treatments and avulsion of the nails is used to reduce oral therapy’s adverse effects and duration.