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 onymosis

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 some type of 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, but the nails thickened and flaked (subungual hyperkeratosis) and the discoloration of the nail to colors such as yellow, green, brown or black (dyschromia) and separation of the nail bed from the nail (Onycholysis) are common symptoms.

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


Approximately half of all nail complaints are the result of a fungal infection, which makes 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.

The reason for this is not entirely clear, but the slower growth of the toenails with respect to 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 the use of plastic shoes, are ideal conditions for these organisms, which facilitates 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 of time, 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 infection.

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 to visualize the fungal elements and an immediate diagnosis of onychomycosis, with it you can also distinguish dermatophytes and yeasts.

To identify exactly what is the causative agent, mycological cultures can be performed in appropriate media in the laboratory from samples and scraped nails, in order to demonstrate its existence and the species of fungi that are 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.

Normally this type of laboratory tests, require a few weeks before presenting the results.

For the identification of dermatophytes it will require a minimum of two weeks of incubation.

If there is growth of the organisms, 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 there are several factors that 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 been shown to increase 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 than others 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 of the disease.

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 the treatment of 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 cyclopirox 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 cyclopirox and amorolfine solutions penetrate through all nail layers but have low efficacy when used as monotherapy.

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

For efinaconazole and cyclopirox 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 (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 the treatment of onychomycosis.

These therapies offer much shorter treatment regimens, higher cure rates and less occurrence of 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 are used to reduce the adverse effects and duration of oral therapy.