Onychomycosis

Tiny things called fungus can grow on nails.

This can make a nail look yellow or white. The nail might also get very thick. It can happen to fingers, but it is more common on toes.

Sometimes the nail can break or pull away. This can happen if the infection grows. It can even cause a bad smell. Most of the time, it does not hurt.

Men get this more often than women. Older people get it more often, too. You can get it from damp places like pools. It is good to keep your nails healthy.

Onychomycosis is a fungal infection of the nail.

This can happen to fingernails, but it is more common on toenails.

When you have this infection, your nails might change. They may turn white, yellow, black, or even green. The nails can also become very thick. Sometimes, the nail becomes brittle and breaks. It might even pull away from the nail bed.

In some cases, there may be a bad smell. Most of the time, it does not hurt.

Many things can cause this. Different types of fungus, like dermatophytes, are often responsible. People can get it from damp places like pools or gyms. It is more common in men and older people.

Doctors can find the infection by looking at the nail. They may also use lab tests to be sure. Some people take medicine called terbinafine by mouth. This medicine helps clear the fungus. Trimming the nails can also help. Even after treatment, the infection can sometimes come back. It is wise to avoid using old shoes to help prevent this.

Onychomycosis is a common fungal infection that affects the nails.

While it can happen to fingernails, it is much more frequent in toenails. This condition can change how a nail looks and feels. Nails might turn white, yellow, black, or even green. They can also become very thick or quite brittle. Sometimes, the nail may even separate from the nail bed.

In some cases, the area might have a foul smell. Most people do not feel pain unless the infection is severe.

Many different kinds of fungus cause this infection. Dermatophytes are the most common type in temperate western countries. In hot and humid tropical areas, yeasts called Candida are more common. Other molds can also play a role in the infection. The way the fungus enters depends on the type. For example, Candida often affects fingernails in people who submerge their hands in water often. Molds are more common in people over the age of 60. This happens because the nails may lose some ability to defend themselves.

Scientists have studied these fungi for a long time. Georg Meissner first determined that this was a fungal infection in 1853. Since then, researchers have identified many specific types of fungi. One very common type is called Trichophyton rubrum. Other types include T. interdigitale and Epidermophyton floccosum. Some names have even changed over time in medical labs. For instance, the name Scytalidium was recently changed to Neoscytalidium. Understanding these names helps doctors pick the right way to help.

About 10 percent of adults have this nail infection. It affects men more often than women. Older people are also at a higher risk for the condition. This can happen because of slower nail growth or weaker immune systems. Factors like diabetes or poor blood circulation can also make it more likely. People might get it from damp places like gyms or swimming pools.

Doctors use lab tests to be sure of the cause. They might use a KOH smear or a culture to check nail clippings.

There are several ways to treat the infection. Some people take a pill called terbinafine by mouth. This medicine is quite effective but can sometimes affect the liver. Other options include using a topical nail polish or cream. One medicine called efinaconazole has shown good results in trials. Trimming the thick nails can also help the treatment work better. Even after treatment, the infection can return in about half of all cases. Using new shoes instead of old ones might help prevent it from coming back.

Onychomycosis is a medical term for a fungal infection of the nails.

This condition affects about 10 percent of the adult population. It is much more common in toenails than in fingernails. The infection changes the physical structure and appearance of the nail. Nails may become thick, brittle, or discolored with white, yellow, black, or green patches. In advanced cases, the nail can separate from the nail bed.

This can cause the nail to break off completely. While often painless, severe cases can cause inflammation and pain in the surrounding skin.

The infection is caused by various pathogens within the fungus kingdom. Dermatophytes are the most common cause in temperate western countries. One specific fungus, Trichophyton rubrum, is the most frequent dermatophyte involved. In tropical or subtropical regions with high humidity, Candida yeasts and nondermatophytic molds are more common. For example, Candida species often affect fingernails in people who frequently submerge their hands in water. Molds, such as those in the genus Neoscytalidium or Aspergillus, are more frequent in people over age 60. This is often due to a slight weakening in the nail's ability to defend itself.

Doctors classify onychomycosis into five distinct types based on how the fungus invades. Distal subungual onychomycosis is the most common form. In this type, the fungus invades the nail bed and the underside of the nail plate. White superficial onychomycosis (WSO) occurs when fungus invades the superficial layers of the nail plate. This creates "white islands" and accounts for about 10 percent of cases. Proximal subungual onychomycosis involves the fungus penetrating the nail through the proximal nail fold. This is rare in healthy people but common in those who are immunocompromised. Finally, endonyx onychomycosis and Candidal onychomycosis represent other specific patterns of invasion.

Understanding the history of this condition helps us see how medical science has progressed. In 1853, Georg Meissner first determined that these nail changes were the result of a fungal infection. Since then, scientists have identified many specific species. They have also updated the names used in medical laboratories to ensure accuracy. For instance, the name Scytalidium was recently changed to Neoscytalidium. Some older names, like Trichophyton mentagrophytes, are now restricted to different types of infections. These scientific advancements allow doctors to identify exactly which fungus is causing the problem.

Many factors increase the risk of developing this infection. Advancing age, particularly over 60, is a major risk factor. This is due to diminished blood circulation, slower nail growth, and reduced immune function. Men are affected more often than women. Other risks include having athlete's foot, diabetes, or poor circulation. People who frequent damp public places like gyms or swimming pools are also at higher risk. Wearing shoes that do not allow for ventilation can increase moisture and encourage fungal growth.

Diagnosis is usually suspected by looking at the nail but must be confirmed with laboratory tests. Doctors often use nail scrapings or clippings for these tests. Common methods include a potassium hydroxide (KOH) smear, a culture, or a histology examination. A polymerase chain reaction (PCR) test can also be used. A nail plate biopsy with a periodic acid-Schiff (PAS) stain is considered very useful for confirmation. It is important to distinguish onychomycosis from other conditions like nail psoriasis or melanoma. This ensures that the patient receives the correct treatment for their specific issue.

Treatment options vary depending on the severity and type of infection. Oral terbinafine is one of the most effective medications, with a 76 percent effectiveness rate. However, it can be associated with liver problems, so doctors must monitor patients. Topical treatments include nail polishes like efinaconazole or ciclopirox. Efinaconazole has shown cure rates significantly higher than ciclopirox in clinical trials. Some newer topical medications, such as Terclara, were launched in Sweden in 2024 to provide effective treatment with fewer side effects. Even with treatment, the infection can return in up to half of all cases. To reduce the risk of recurrence, patients should avoid using old shoes after they have finished treatment.