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How To Tell If You Have A Fungal Nail Infection?

fungal nail infection, doctor examining a fungal toenail infection

Fungal infection of the nail is termed onychomycosis. Different fungal organisms may infect the nails with different presentations affecting any part of the nail including nail bed, nail matrix, and plate. Fungal nail infection is not a serious health problem, but it may negatively alter the appearance of the nail. It is highly contagious and can spread to healthy people easily from an infected person. It occurs more often in toenails than fingernails. How do you know if you are having a fungal nail infection? Read on to find out more about it!


Fungal nail infection is one of the most commonly occurring dermatological complications. The rate of fungal infection has increased in Asia lately with the increasing incidence of Diabetes and expanding aging population. Among a wide variety of superficial fungal infections,  the most difficult to cure is toenail onychomycosis. The prevalence of onychomycosis has been reported to be 20% in East Asia whereas in Southeast Asia the prevalence of onychomycosis is relatively low. This was partially confirmed by a large scale-survey in Asia in the late 1990s in which the prevalence of onychomycosis was lower in tropical countries (3.8%) than in subtropical countries and the countries in the temperate zone (18%)

What causes fungal nail infection?

The great majority of superficial fungal infections are caused by dermatophytes, which belong to one of three genera (Trichophyton, Epidermophyton, and Microsporum), with T. rubrum being the most prominent cause of nail infection. Living in warm and moist places causes fungal nail infection as fungi flourishes in humid conditions. 

Symptoms and Signs 

Changes in nail appearance can hint at the presence of a fungal infection. Some of these changes are:

  • Turning of nail color into pale yellow 
  • Thickening of the affected nail 
  • Distortion of nail shape 
  • The appearance of a spot on side of nails 
  • Broken or brittle nail
  • Presence of debris under the nail 
  • White spots in the nail
  • Damaged nail surface 
  • Pain in the nail 
  • Loss of nails
  • Foul smell from the infected nail 

Risk Factors 

These are some of the few risk factors that increase the chance of developing a fungal infection:  

  • Age: More common in age > 60
  • Immunosuppression: Weak immune system  
  • Uncontrolled diabetes mellitus 
  • Chronic renal failure 
  • Chronic obstructive pulmonary disease (COPD)
  • Post H1N1 influenza 
  • Living in a warm and humid place 
  • Use of artificial nail 
  • Following nail injury 
  • Pre-existing disease compromising adequate blood flow 


The diagnosis is made by a combination of physical examination and laboratory investigations. Your dermatologist or physician will start with a medical history and perform laboratory test to diagnose fungal infection includes 

  • Potassium hydroxide test to see the development of fungi on the nail 
  • Nail biopsy includes examining the small piece of the affected  nail and checking under a microscope 
  • Fungi culture: This is used to check the growth of fungi in the nail. The culture may take up to 4-6 weeks.
  • The polymerase chain reaction is also a useful method for diagnosis of the fungal nail infection, but it is not used routinely. 

Differential Diagnosis 

Only about 50 percent of the discolored nail cases are confirmed to be infected with a dermatophyte on culture. Other causes which have similar clinical presentation are:

  • Onychogryphosis: This is due to the thickening of the nail following trauma 
  • Trauma: Due to tight shoes, nail-biting 
  • Eczema 
  • Lichen planus 
  • Raynaud’s phenomenon 
  • Systemic disease: which includes eg Thyroid disease, Diabetes mellitus, Peripheral arterial disease 

Is nail fungus contagious?

The most common question that arises about nail fungus is, is it contagious? The answer: Yes, it can be. The fungus can spread from one person to another on close contact or when sharing a common household because they thrive in places where the air is moist. This can also happen in places like swimming pools, gyms, locker rooms, and communal showers. Nail fungus can even spread from one nail to another within the same person. 

How can nail fungal infection be treated?

With millions of dollars being spent annually on oral and topical prescriptions, laser treatments, over-the-counter products, and home remedies, it is obvious that people are quite bothered by their fungal toenail infections and are determined to get rid of them. Unfortunately, this is easier said than done. To successfully cure fungal infection of the nails, it requires a long treatment duration that may extend to a full year. Even then, complete cure, defined as clinical cure (implying nail clearing) plus mycological cure (both negative microscopy and dermatophyte culture), is often unattainable.

Topical antifungal agents are usually used but they are ineffective. Oral terbinafine is considered to be the first-line treatment for diagnosed nail infection; the treatment course is 6 weeks for fingernails and 12 weeks for toenails. Azoles are also commonly used. Surgical treatment is done when medical treatment fails or unresponsive to medical treatment. The choice of surgical treatment includes surgical debridement or removing the affected nail. Laser therapy for fungal nail infection has shown promising outcomes in recent advances. 

The infection is considered to be cured when you see a healthy nail growing back at the base.


  • Keep your foot and hand clean and dry.
  • Wear clean socks every day.
  • Do not wear other people’s shoes. 
  • Do not share a towel.
  • Do not share nail clippers or scissors. 
  • Don’t walk barefoot in areas like locker rooms or public showers.
  • Apply topical antifungal medication regularly to the feet and toenails
  • Discard old shoes and “rest” shoes periodically to decrease their exposure to fungi
  • Apply an antifungal powder/spray to the inside of shoes once a week or more

Long term Outlook

The prognosis is variable and depends upon the type of infection as well as  host factors such as immune status,comorbidities and age. Fingernails have a much higher rate of cure, usually 70 %. If left untreated, fungal infections are usually progressive and can even  lead to the destruction of the nail plate. 


The outcome of fungal infection may not be good in some cases, and may result in complications such as: 

  • Poor cosmetic appearance of hand and feet 
  • Disfigurement of the nail plate 
  • Cellulitis (skin infection), osteomyelitis (bone infection), sepsis, and necrosis in elderly people and people with diabetes. 
  • Pain and limitation of function in elderly people.

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