fungal nails

Medical Author : Allison Harvey, MD, FACEP

Medical Editor : Melissa Conrad Stöppler, MD

 

A woman holding her feet and toes.

Introduction to Fungal Nails (Onychomycosis, Tinea Unguium)

Many changes in fingernails or toenails may cause people to think they have a fungal infection of the nails, medically known as onychomycosis.

Fungal infection of the nails sometimes makes the condition sound contagious or related to poor hygiene. In fact, up to 10% of all adults in Western countries have fungal infection of the nails. This percentage increases to 20% of adults who are age 60 or older.

In reality, abnormal-looking nails may be caused by a number of conditions including, but not limited to, fungal infection. There are many other reasons why your nails may look different.

 

Examples of conditions that are often mistaken for fungal nails including yellow nails (onycholysis), hematoma, green nails (caused by Pseudomonas bacteria), pitted nails (usually associated with psoriasis), and nail infection (paronychia).

What other conditions can be mistaken for fungal nails?

Here are some other conditions you may have instead of fungal nails:

  1. Lines and ridges: These are common and may be considered normal. They may worsen during pregnancy. A large groove down the center of the nail can be caused by nail biting.
  2. Senile nails: As you age, the nails become brittle, develop ridges and separation of the nail layers at the end of the nail. To avoid this, try to clean solutions, and don't soak the nails in water.
  3. Whitish or yellowish nails can occur due to onycholysis. This means separation of the nail from the nail bed. The color you see is air beneath the nail. The treatment is to trim the nail short, don't clean under it, polish if you want to hide the color, and wait two to three months.
  4. Red or black nails due to a hematoma, or blood under the nail, usually occur from trauma (like whacking yourself on the thumb with a hammer). The discolored area will grow out with the nail and be trimmed off as you trim your nails. If you have a black spot under your nail that was not caused by trauma, you may want to see a dermatologist to make sure it is not melanoma.
  5. Green nails can be caused by Pseudomonas bacteria, which grow under a nail that has partially separated from the nail bed. The treatment is to trim the nail short every four weeks, don't clean it, polish if you want to hide the color, and wait two to three months. It is also advised to avoid soaking the nail in any sort of water (even if inside gloves) and to thoroughly dry the nail after bathing. If the problem continues, there are prescription treatments that your doctor may try.
  6. Pitted nails may be associated with psoriasis or other skin problems that affect the nail matrix, the area under the skin just behind the nail. This is the area from which the nail grows. Nails affected by psoriasis can also be tan in color.
  7. Swelling and redness of the skin around the nail is called paronychia. This is an infection of the skin at the bottom of the nail (cuticle). If the infection is acute (has a rapid onset), it is usually caused by bacteria. It may respond to warm soaks but will often need to be drained by a doctor. A chronic paronychia occurs when a cuticle becomes inflamed or irritated over time. Sometimes, yeast will take advantage of the damaged skin and infect the area as well. Therapy begins with keeping the skin dry and out of water. Sometimes a steroid cream such as hydrocortisone can be used with success. If the problem continues, a physician should be consulted.
  8. Chronic nail trauma, such as repeatedly starting and stopping, kicking, and other athletic endeavors, can cause damage to the nails that can look a lot like fungal nails. This sort of repetitive trauma can also occur with certain types of employment or wearing tight-fitting shoes.
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Microconidia of the fungus Trichophyton which inhabit the soil and can lead to fungal infections of the skin , hair or nails.

What causes fungal nails, and what are some of the risk factors?

In normal, healthy people, fungal infections of the nails are most commonly caused by fungus that is caught from moist, wet areas. Communal showers, such as those at a gym or swimming pools are common sources. Athletes have been proven to be more susceptible to the fungus. This is presumed to be due to the wearing of tight-fitting, sweaty shoes associated with repetitive trauma to the toenails. Having athlete's foot makes it more likely that the fungus will infect your toenails.

Elderly people and people with certain underlying disease states are also at higher risk. These include anything that impairs your immune system can make you prone to getting infected with the fungus. These include conditions such as AIDS, diabetes, cancer, or taking any immunosuppressive medications like steroids.

Is nail fungus contagious?

While the fungus must be obtained from someplace, it is not highly contagious. Nail fungus is so common that finding more than one person in a household who has it is hardly more than a coincidence. It can be transmitted from person to person but only with constant intimate contact.

 

Examples of distal subungal onychomycosis, proximal subungal onychomycosis, and Candidal onychomycosis.

What are the symptoms and signs of fungal nails?

There are many species of fungi that can affect nails. By far the most common, however, is called Trichophyton rubrum. This type of fungus has a tendency to infect the skin (known as a dermatophyte) and manifests in the following specific ways.

  • Starts at the ends of the nails and raises the nail up: This is called "distal subungal onychomycosis." It is the most common type of fungal infection of the nails (90%). It is more common in the toes than the fingers. Risk factors include older age, swimming, athlete's foot, psoriasis, diabetes, family members with the infection, or a suppressed immune system. It usually starts as a discolored area at a corner of the big toe and slowly spreads toward the cuticle. Eventually the toenails will become thickened and flaky. Sometimes, you can also see signs of athlete's foot in between the toes or skin peeling on the sole of the foot.
  • Starts at the base of the nail and raises the nail up: It is called "proximal subungal onychomycosis." This is the least common type of fungal nail (3%). It is similar to the distal type, but it starts at the cuticle (base of the nail) and slowly spreads toward the nail tip. This type almost always occurs in people with a damaged immune system.
  • Yeast onychomycosis: This type is caused by a yeast called Candida and not by the Trichophyton fungus named above. It is more common in fingernails and is a common cause of fungal fingernails. Candida can cause yellow, brown, white, or thickened nails. Some people who have this infection also have yeast in their mouth or have a chronic paronychia (see above) that is also infected with yeast.

  • A doctor examining a patient’s toenails.

    How are fungal nails diagnosed?

    Physical exam alone has been shown to be an unreliable method of diagnosing fungal nails. There are many conditions that can make nails look damaged, so even doctors have a difficult time. Therefore, laboratory testing is almost always indicated. A nail sample is obtained either by clipping the toenail or by drilling a hole in the nail. That piece of nail is sent to a lab where it can by stained, cultured, or tested by PCR (to identify the genetic material of the organisms) to identify the presence of fungus. Staining and culturing can take up to six weeks to get a result, but PCR, if available, can be done in about one day. Most of the medications used to treat nail fungus have side effects, so you want to make sure of what you are treating.

  • A person trimming their toenails.

    How is nail fungus treated?

    Keeping nails trimmed and filed can help to reduce that amount of fungus in the nails and is highly recommended. A podiatrist or dermatologist may shave the top layer of the nail off or even remove part of the nail.

    Creams and other topical medications have traditionally been less effective against nail fungus that oral medications. This is because nails are too hard for external applications to penetrate. A medicated nail lacquer, ciclopirox (Penlac) topical solution 8%, has been approved to treat finger or toenail fungus that does not involve the white portion of the nail (lunula) in people with normal immune systems. It only works about 7% of the time. There is some evidence that using an antifungal nail lacquer containing amorlfine can prevent reinfection after a cure, with a success rate of about 70%.

    Efinaconazole (Jublia) is a medication approved in 2014. It is a topical (applied to the skin) antifungal used for the local treatment of fungal infections of the toenails. Daily application is required for 48 weeks.

    Tavaborole (Kerydin) is another new medication that is indicated for onychomycosis of the toenails due to Trichophyton rubrum or Trichophyton mentagrophytes. Daily use for 48 weeks is also required.

  • A woman taking antifungal nail medication.

    How is nail fungus treated? (Continued)

    Oral antifungal therapy works about 50% of the time. It can take nine to 12 months to see if it has worked or not, because that is how long it takes for the nail to grow out. Even when therapy works, the fungus may come back about 20%-50% of the time.

    Oral medications that are effective against nail fungus include:

    • Griseofulvin (Fulvicin, Gifulvin, Gris-Peg): This drug has been the mainstay of oral antifungal therapy for many years. Although this drug is safe, it is not very effective against toenail fungus. Newer agents have largely supplanted it.
    • Terbinafine (Lamisil): This drug is taken daily for 12 weeks. The drug is safe, effective, and produces few side effects. However, it must be used with caution in patients with liver disease.
    • Itraconazole (Sporanox): This is often prescribed in "pulse doses" -- one week per month for two or three months. It can interact with some commonly used drugs such as the antibiotic erythromycin or certain asthma medications.
    • Fluconazole (Diflucan): This drug may be given once a week for several months. The dosing of this drug may need to be modified if the patient has impaired kidney function or is taking it simultaneously with certain other medications. It is not as effective as Lamisil or Sporanox and should be used cautiously in patients with liver disease.

    There are several innovative treatments that are still being tested:

    • Photodynamic therapy uses application of light-activated agents onto the nail followed by shining light of a proper wavelength on the nail.
    • Use of electrical current to help absorption of topical antifungal medications into the nail
    • Use of a special nail lacquer that changes the micro-climate of the nail to make it inhospitable for the fungus to grow. If this works, it may be an inexpensive way to treat this problem in the future.
    Vinegar is a commonly recommended home remedy. Its effectiveness is highly doubtful. Some people apply various oils and other tonics to their nails as well.

  • Medication pills on top of money.

    Are oral medications for nail fungus toxic?

    The newer drugs are unlikely to cause any liver problems in patients without known liver disease. Blood tests are not needed for once weekly treatment with fluconazole; however, people taking longer courses often have their liver function tested before starting the medicine and then retested during the course of treatment.

    What about the cost of oral medications?

    A further consideration is cost. Because newer oral antifungal agents are very expensive, some insurance companies balk at paying for what they consider a "cosmetic issue," unless nail fungus causes pain or other functional symptoms. Terbinafine and fluconazole are now available as generic drugs and are quite inexpensive.

  • A person wearing sandals in in a gym locker room shower.

    How do you prevent fungal nails?

    No one knows where a specific person catches the fungus, as it is everywhere. However, since the fungus does thrive in warm moist areas (like sweaty feet), there are certain areas one should avoid or use with caution. Shower floors, locker rooms, and swimming pools are suspected of being sources of the fungus, although there are no studies proving this fact. Nail polish and acrylic nails also make the nail less "breathable" and make the nail more susceptible to fungal infection. Fungi are everywhere -- in the air, the dust, and the soil. Hygienic measures such as spraying socks and footgear sound sensible, and perhaps these measures can even help a little bit. However, avoiding tight, nonbreathing shoes or steering clear of athletic facility floors may very well be the best prevention available. Daily washing of the feet and drying between the toes can help to prevent nail fungus. The fungi carried on the coats of pets, like cats and dogs, don't often cause nail fungus. Wearing white socks does not help.

  • Photo of a woman’s healthy toenails.

    What is the prognosis of fungal nails?

    Curing fungal nails can be difficult and treatment can take up to 18 months. Relapse and reinfection are common (40%-70% reinfection rate). Trying to remove or modify your risk factors, if possible, is essential to preventing reinfection. People who have medical illnesses that predispose them to fungal nails can have an even more difficult time eradicating the fungus.

    Conclusion

    Nail fungus causes only 50%-60% of abnormal-appearing nails. It can be hard to tell the difference between the different causes of discolored nails (even for doctors). Onychomycosis is often not treated. Reasons to receive treatment include

    1. diabetes,
    2. previous leg infection (cellulitis),
    3. if you have pain or discomfort from your nails, or
    4. you would like them treated for cosmetic reasons.

    Treatment failures and recurrences are common.

    Prevention is the key. The following preventive measures may be helpful:

    1. Keep your toenails short, and don't dig into the corners of your nails when cutting toenails.
    2. Keep feet clean, and dry them thoroughly.
    3. Wear dry socks and no tight shoes.
    4. Alternate your exercise shoes.
    5. Don't soak your hands in water or use harsh cleaners.
    6. Treat athlete's foot when it occurs.

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