Toenail fungus

Toenail fungus is an infection that gets in through cracks in your nails or cuts in your skin. It can make your toenails change color or become thicker and can be very painful. Because toes are often warm and damp, fungus grows well there. Different...

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Toenail Fungus

Toenail fungus is an infection that gets in through cracks in your nail or cuts in your skin. It can make your toenail change color or get thicker and can be very hurtful. Because toes are often warm and damp, fungus grows well there. Different kinds of fungi and sometimes yeast affect different parts of the nail. Left untreated, an infection could spread to other toenails, skin, or even your fingernails. It is a condition that disfigures and sometimes destroys the nail. It is also called onychomycosis. When fungus infects the areas between your toes and the skin of your feet, it's called athlete's foot (tinea pedis). 

It can be caused by several different types of fungi. Fungi are microscopic organisms related to mold and mildew.   These fungi thrive in the dark, moist, and stuffy environment inside shoes. As they grow, fungi feed on keratin. Keratin is the protein that makes up the hard surface of the toenails.

Causes of Toenail Fungus

Typical causes of this fungus are:

  • Causative pathogens include Candida and nondermatophyte molds, in particular members of the mold genus Scytalidium (name recently changed to Neoscytalidium), Scopulariopsis, and Aspergillus. Candida species mainly cause fingernail onychomycosis in people whose hands are often submerged in water. 
  • Scytalidium mainly affects people in the tropics, though it persists if they later move to areas of temperate climate.
  • Other molds more commonly affect people older than 60 years, and their presence in the nail reflects a slight weakening in the nail's ability to defend itself against fungal invasion.
  • Dermatophyte (a common type of fungus called that can be easily picked up by your hands or feet)

Symptoms of Toenail Fungus

  • When a toenail develops a fungal infection, it typically turns yellow or brown. It becomes thick and overgrown. Foul-smelling debris also may accumulate under the nail.  
  • As the infection continues, the nail may crumble gradually and fall off.  Or, it may become so thick that the affected toe feels uncomfortable or painful inside shoes. 
  • A less common variety of toenail fungus is called white superficial onychomycosis. The nail turns white rather than yellow or brown. The surface becomes soft, dry, and powdery.
  • Infected nails are usually thicker than normal and could be warped or oddly shaped.
  • Nails smelling slightly foul 

Risk Factors of Toenail Fungus

Factors that increase the risk of developing toenail fungus include: 

  • Wearing tight-fitting shoes or tight hosiery 
  • Practicing poor foot hygiene 
  • Wearing layers of toenail polish, which doesn't allow the nail to breathe 
  • Being military personnel, an athlete, or a miner. This is because toenail fungi may spread from foot to foot on the floors of showers and locker rooms.  
  • Having a chronic illness, such as diabetes 
  • Having a circulatory problem that decreases blood flow to the toes
  • Toenails on the big toe and little toe are the most likely to develop a toenail fungus. This may be partly because the big toe and little toe are constantly exposed to friction from the sides of shoes.
  • Men are more likely to get it than women.
  • Diabetes
  • Chronic smokers
  • Weak immune system
  • If the person spends more time in the water. 

Complications of Toenail Fungus

  • Increased pain with potential difficulty walking
  • Spread of fungus to other toenails and/or foot and/or other body parts 
  • Permanent damage to your nail
  • Permanent loss of the affected nail
  • Bacterial infections that can spread to other areas of the body and/or bloodstream (cellulitis) requiring oral antibiotics and/or amputation

Diagnosis of Toenail Fungus

Symptoms, past medical history, and the onset of the issue should be explained to the treating doctor pretty much in detail. A history of illness, such as poor circulation or diabetes may decrease your resistance to infection or interfere with blood flow to your toes.

A skin disease called psoriasis can sometimes cause nail problems that look similar to a fungal infection. As a result, your doctor may ask whether you or a family member has psoriasis. It is possible for psoriasis and fungal infection to affect the same toenail.  

Your doctor will examine your affected toenail or toenails. Often the diagnosis can be made based on the appearance of toenails. Your doctor may take small samples of the affected nails. These samples will be sent to a laboratory where they are tested for fungi and other infectious agents.

Other tests that are performed for accurate diagnosis of the condition are:

  • A potassium hydroxide smear
  • Culture
  • Histology examination
  • Polymerase chain reaction.
  • The sample examined is generally nailed scrapings or clippings.
  • Nail plate biopsy with periodic acid-Schiff stain appears more useful than culture or direct KOH examination.
  • To reliably identify nondermatophyte molds, several samples may be necessary.

Treatment for Toenail Fungus

Treatment may begin with your doctor removing as much of the infected nail as possible. This can be done by trimming the nail with clippers or filing it down. 

If the infection is mild and limited to a small area of your nail, your doctor can prescribe a topical antifungal agent in the form of a cream, solution or medicated nail polish.  

If the infection is in a wider area of your nail or several nails, a topical agent alone is less likely to be effective. So, your doctor may prescribe an oral antifungal medication. Most commonly, doctors prescribe terbinafine (Lamisil) first. A commonly used alternative is itraconazole (Sporanox), but it can cause serious drug interactions.  

Topical agents include ciclopirox nail paint, amorolfine, and efinaconazole.

Some topical treatments need to be applied daily for prolonged periods (at least 1 year). Topical amorolfine is applied weekly. Topical ciclopirox results in a cure in 6% to 9% of cases; amorolfine might be more effective. Ciclopirox, when used with terbinafine, appears to be better than either agent alone. In trials, about 17% of people were cured using efinaconazole as opposed to 4% of people using placebo. Although eficonazole, P-3051 (ciclopirox 8% hydrolacquer), and tavaborole effectively treat a fungal infection of toenails, complete cure rates are low.

When toenail fungus is resistant to treatment in very severe cases, it may be necessary to surgically remove the entire nail.

Prevention of Toenail Fungus

To help to prevent toenail fungus:  

  • Wear comfortable shoes and hosiery that allow your feet some breathing room.  
  • Wear shoes, sandals, or flip-flops in community showers or locker rooms.  
  • Wash your feet every day. Dry them thoroughly, and use good-quality foot powder.  
  • Wear clean socks or stockings every day.  
  • Keep your toenails trimmed.  
  • Disinfect pedicure tools before you use them.

Nail fungus can be stubborn. If you had a severe infection, it’s possible to clear the infection. However, a healthy-looking nail may be unrealistic, but you can expect the nail to look better and feel more comfortable. If you have a fungal nail infection but are also exhibiting possible symptoms of subungual melanoma, see your doctor immediately.

Since early detection is crucial to a positive prognosis, it’s important to be proactive in examining your nails for any signs of melanoma. Don’t hesitate to see a doctor if you think you might have either toenail fungus or subungual melanoma.