Nail Fungus - Causes, Symptoms and Treatment

Onychomycosis or tinea unguium, popularly known as mycosis of nail, is the name given to nail infection caused by fungi.

Onychomycosis is a common infection that affects about 10% of the adult population and 20% of the elderly. Its symptoms are usually of aesthetic rather than clinical origin, with darkening and thickening of the nail being the most common signs.


What is onychomycosis

As explained in the introduction to this article, onychomycosis is a fungal infection of the fingernails or toenails.

Fungal infections of the nails are usually caused by a fungus that belongs to a group called dermatophytes, which can also cause infections in the skin and the skin, as in the case of the chilbler (athlete's foot). Another group of fungi that can also cause nail fungus are yeast. In general, yeasts cause onychomycosis on the hands and the dermatophytes cause onychomycosis on the toenails.

Toenail fungus is not a fatal disease, but can cause pain, discomfort and nail destruction, leading to significant emotional effects that can have a significant impact on quality of life.

How to get onychomycosis

Fungi that cause nail fungus are usually acquired in the environment, especially in hot and humid areas, which are the means conducive to fungal growth. Toilets, showers, locker rooms and public swimming pools are examples of places that often harbor fungi. Attending these public spaces barefoot is an important risk factor for getting ringworm on the nails.

Contact with the fungus alone is usually not sufficient to acquire onychomycosis. There is usually a need for small lesions between the nail and the skin so that the fungus can penetrate under the nail and lodge. It is also necessary that the nail is often exposed to humid environments so that the fungus can multiply more easily.

Nail onychomycosis on the toenails is much more common than on the nails of the hands. The feet are usually more exposed to damp places, not only when walking barefoot in public places, but also for spending much of the day enclosed in socks and shoes. On hot days, your feet can be covered for several hours at a time covered in sweat. Heat, lack of light and moisture is all that a fungus wants to proliferate.

Also, the toes are at the point of the body most distant from the heart, not being so well vascularized with the fingers of the hand. In this way, antibodies and the body's defense cells do not reach the toenails with as much ease as other parts of the body.

Is nail fungus contagious?

Nail fungus can be transmitted from one person to another, but this form of infection is uncommon. Sharing nails or nail clippers can be a form of transmission, but in general you need intimate and frequent contact, such as living in the same house for one person to get onychomycosis from the other.

You do not get nail fungus just by shaking hands or touching objects manipulated by someone infected.

Risk factors

The presence of some factors favors fungal nail infection. For example, patients with footworms (athlete's foot), which is a fungal infection of the skin of the fingers, have a greater risk of having fungal nail infections as well. Other risk factors are:
  • Diabetes mellitus
  • Advanced age
  • HIV
  • Use of immunosuppressive drugs
  • Immunological problems
  • Family history of onychomycosis
  • Psoriasis
  • Problems of blood circulation of the lower limbs

Athletes are also a risk group for onychomycosis. These individuals often have their feet often wet and wet with perspiration and have a higher incidence of nail trauma due to the impact of their physical activities.


Nail mycosis usually produces no symptoms other than cosmetic nail changes. In more severe cases, however, it can cause pain. In diabetic or immunosuppressed patients, onychomycosis can serve as a gateway to bacteria, favoring the onset of secondary infections such as erysipelas or cellulitis.

The nail lesions caused by onychomycosis present some variation in their presentation, depending on the type of fungus and the severity of the infection. Nail mycosis usually has one or more of the following signs:
  • Thickening of the nail
  • Fragility of the nail, leaving it brittle
  • Distortions in the shape of the nail
  • Loss of nail glow, leaving it opaque
  • Darkening of the nail
  • Fingering of the nail in relation to its bed in the skin

The most common forms of onychomycosis are:

1. Onychomycosis distal subungual : this is by far the most common form and is characterized by the infection of the nail tip. The first toe (toe) is usually the first to be affected. The infection starts with a whitish, yellowish or brownish discoloration on one side of the nail, slowly extending across the nail toward the cuticle. The nail may peel off and the tip usually breaks and falls, exposing the skin that serves as a bed for the nail.

2. Proximal subungual onychomycosis - is the least common form of onychomycosis. Its presentation is very similar to the subungual distal onychomycosis, however, the progression occurs in an opposite way, starting near the cuticle and then extending towards the tip of the nail. This type of nail fungus usually occurs in immunosuppressed patients, being common in individuals with HIV.

3. White superficial onychomycosis - is a common form in children, but that in adults corresponds to only 10% of cases of nail fungus. It is characterized by the appearance of white spots on the surface of the nail, usually closer to the cuticle than to the tip. When untreated, the spots tend to spread centrifugally throughout the nail, leaving it almost all white, besides rough and brittle.


The nail lesions of onychomycosis may resemble nail injuries from other diseases, such as psoriasis, eczema, trauma, lichen planus, iron deficiency, etc.

Most studies attest that onychomycosis accounts for only half of all cases of nail injury. In several situations, it is not possible to state that the patient suffers from onychomycosis just by looking and examining for the nail.

Therefore, it is important to unequivocally demonstrate the presence of the fungus before initiating antifungal treatment. To do this, the doctor will do a small scraping of your fingernail in order to collect samples for laboratory evaluation in search of fungi.


Nail mycosis is a difficult infection to treat because the nails grow slowly and receive little blood supply. Until the recent past, the drugs used to treat onychomycosis were not very effective and the results were often disappointing.

In the last decade, however, treatments for patients with onychomycosis have improved substantially, mainly because of the introduction of more effective oral antifungal medications.

Recent studies show that oral medications such as Terbinafine and Itraconazole have higher cure rates than Griseofulvin and Ketoconazole, the most commonly used drugs.

Curing rates of major antifungal agents:
  • Terbinafine (73 to 79%)
  • Itraconazole (56-70%)
  • Griseofulvin (54-66%)
  • Fluconazole (43 to 52%)

Treatment with Terbinafine with oral tablets should be done with 1 250 mg tablet per day for 6 weeks for hand onychomycosis or 12 weeks for foot onychomycosis.

Topical nail fungus topical treatment with nail polish, such as Ciclopirox, usually does not work alone but may be used as a complement to treatment with oral terbinafine or Itraconazole.

Once the mycosis of the nail is cured, if the patient is not careful the reinfection rate can reach 50%. Therefore, care must be taken with the feet so that the nails do not get colonized by fungi again.

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