Understanding Fungal Nail Infections!

What are fungal nail infections?

Fungal infection of the nail, also known as onychomycosis, compromises over 50% of all nail disease with an estimated prevalence of 5.5%. They can affect the toenails, fingernails, or both.


Fungal nail infections are also known as tinea unguium in the case of dermatophyte infections.

Who gets fungal nail infections?

Onychomycosis is common in older aged adults (over 65 years), diabetics, immunocompromised patients (especially those with HIV disease), and athletes. Onychomycosis may be present amongst family members due to autosomal inheritance (HLA-DR8) or environmental factors. It rarely occurs in children.


Other associated comorbidities include: tinea pedis, tinea manuum, psoriasis, peripheral vascular disease, venous insufficiency, hallux valgus, smoking, asymmetric gait nail unit syndrome, Down syndrome, and obesity.


Predisposing patient factors include: chronic paronychia, hyperhidrosis (eg, with occlusive footwear), nail trauma, and using communal bathing or changing facilities.

What causes a fungal nail infection?

Onychomycosis can be due to infection with dermatophytes or non-dermatophytes such as moulds and yeasts.
  • Dermatophytes (over 75% of cases): Trichophyton rubrum, Epidermophyton floccosum, Microsporum species, Trichophyton verrucosum, Trichophyton tonsurans, Trichophyton violaceum, Trichophyton soudanense, Trichophyton krajdenii, Trichophyton equinum, and Arthoderma species.
  • Non-dermatophyte
    • Moulds (10% of cases): Aspergillus species, Scopulariopsis species, Fusarium species, Acremonium species, Syncephalastrum species, Scytalidium species, Paecilomyces species, Neoscytalidium species, Chaetomium species, Onchocola species, and Alternaria species.
    • Yeasts (uncommon): Candida albicans, and rarely non-albicans candida yeasts (eg, tropicalis, or parapsilosis)
    • For more information, see non-dermatophyte mould onychomycosis.
Emerging evidence of the role of biofilm in fungal nail disease may account for antifungal drug resistance and increased virulence.

What are the features of onychomycosis?​

Onychomycosis may affect a single nail or multiple, commonly affecting the first toenail. It may also affect the surrounding skin, however, very rarely causes systemic involvement.
Clinical types include:
  • Distal and lateral subungual onychomycosis — the distal end and sides of the nail lift or become discoloured and crumble.
  • Superficial white onychomycosis — flaky, white patches and pits appear on the top of the nail plate.
  • Proximal subungual onychomycosis — the proximal nail plate close to the lunula becomes discoloured and thickened. This pattern of disease is often related to underlying HIV infection.
  • Endonyx onychomycosis — milky white discolouration of the nail plate develops without subungual hyperkeratosis or onycholysis.
  • Onychauxis
Features that are observed include:
  • Subungual hyperkeratosis — scaling occurs under the nail
  • Jagged and crumbling of the free end of the nail plate
  • Discolouration of the nail, eg, yellow, white, grey, or green discolouration
  • Ridging, crumbling, and sometimes eventual complete nail plate destruction
  • Scaling on the plantar skin and web spaces due to associated tinea pedis
  • Onychoma or dermatophytoma — a thick localised area of infection in the nail plate.
Onychomycosis may complicate other nail pathology such as trauma or psoriasis.
Candida infection of the nail plate generally results from paronychia and starts near the nail fold (the cuticle). The nail fold is swollen and red, lifted off the nail plate. White, yellow, green, or black marks appear on the nearby nail and spread. The nail may lift off its bed and is tender if you press on it.
Mould infections are similar in appearance to tinea unguium.
superficial white onychomycosis

superficial white onychomycosis


superficial white onychomycosis

Proximal onychomycosis

Proximal onychomycosis


Proximal onychomycosis

What is the outcome of fungal nail infections?

Approximately 20–25% of treated onychomycosis unfortunately relapse due to patient or pathogen factors such as poor circulation, advancing age, diabetes, immunosuppression, severe fungal nail clinical findings, mixed infections, and incomplete treatment. The Onychomycosis Severity Index can be used to predict response to therapy.

What are the complications of fungal nail infections?

Fungal nail infections are often regarded as a trivial cosmetic problem. However, the effect it may have on one’s quality of life is undervalued as it can cause significant pain affecting full mobility and activities, and social stigma.

How is onychomycosis diagnosed?

Physical examination of all nails, and a combination of tools, such as those listed below, may be used to improve speed and accuracy of diagnosis.
  • Dermoscopy may be able to differentiate between onychomycosis, traumatic onycholysis, and melanonychia. Common dermatoscopic findings include linear bands which round proximally and taper distally, discolouration, non-longitudinal homogenous or reverse triangular patterns, subungual keratosis, white/yellow streaks, and nail plate scales.
  • Clippings should be taken from the crumbling free edge of the affected nail. .
  • Fungal cultures can identify the causative organism and is the standard diagnostic test, however, results can take weeks and a large specimen collection may be required. This technique requires the nail to be cleaned with 70% isopropyl alcohol and soapy water prior to specimen collection. Samples should be taken prior to starting any treatment.
  • PCR testing quickly identifies the offending organism and is highly sensitive and specific. It is becoming more commonly available, however is more costly than microscopy or fungal culture testing.

Comparison of normal nails and onychomycosis

normal nails

What is the differential diagnosis of onychomycosis?

Physical examination of all nails, and a combination of tools, such as those listed below, may be used to improve speed and accuracy of diagnosis.
  • Benign conditions include: bacterial infection such as pseudomonas argeuniosa (CAP), psoriasis, lichen planus, subungual and periungual verruca, paronychia, subungual exostosis, onychomatricoma, yellow nail syndrome, and idiopathic/traumatic onycholysis.
  • Malignant conditions include: subungual squamous cell carcinoma and subungual melanoma.

How do you prevent fungal nail infections?

Ringworm is a very common infection, and anyone can contract it. Some people are especially prone to infection, though. Anyone with a compromised immune system is both at a higher risk of being infected and will have a harder time fighting off an infection.


People who use public locker rooms, showers, swimming pools, and similar communal areas that are hot and humid are also at greater risk. Athletes risk infection because they tend to sweat, and their athletic equipment sometimes traps moisture close to the skin. Athletes who make a lot of skin-to-skin contact, such as wrestlers and MMA fighters, are particularly prone to skin infections.


People who spend a lot of time with animals—farmers, veterinarians, and dog groomers, for example—also stand greater risks.


It’s not easy to prevent ringworm completely. However, by taking a few simple steps, your risk of developing an infection will be lower.

Don’t Share
Ringworm spores can live in clothing, sports gear, towels, sheets, and combs for years. Don’t use other peoples’ intimate items if you want to avoid infection.
Slip on Sandals and Slippers
To keep ringworm off your feet, don’t walk around barefoot in locker rooms, public pools, or public showers. Instead, put on a pair of sandals or slippers to give your skin a barrier of protection.
Get Soapy
If you play a contact sport, shower and shampoo carefully after every practice or game. The same rule applies after petting a dog or cat; to avoid transmission of the ringworm fungus from your pets, be sure to wash your hands with soap and water after playing with any mammal.
Change Is Good
To avoid trapping moisture close to your skin, wear loose-fitting clothing made of natural fibers. Change your socks and underwear at least once a day to ward off athlete’s foot and jock itch.
Stay Dry
Fungi love humidity. One of the best ways to keep them away is to stay dry. For instance, completely dry yourself off after showers and baths.
Socks on First
Stay stocking-footed to prevent the spread of any foot fungus to other parts of your body. Before you slide on your underwear, make sure your socks are on tight. This may prevent a case of athlete’s foot from turning into an uncomfortable case of jock itch.
Watch for Patchy Pets
If your pets have patches of missing hair, take them to the vet. That’s one sign of a ringworm fungal infection. Also keep an eye out for a lesion with a scaly center that looks red and irritated around the edges. Sometimes pets will show circular patches of missing hair, and at other times they will display crusty scales. If you have a cat, keep an eye out for excessive grooming, which may be your cat’s way of signaling something is irritating its skin.

Don't let grey nails dampen your spirits any longer.

Armed with knowledge and understanding, you now possess the power to conquer fungal nail infections.
By recognizing the causes, identifying the symptoms, exploring treatment options, and adopting preventative measures, you can overcome this common yet often neglected condition.
Remember, early intervention and a proactive approach are key to achieving healthy, beautiful nails once again.