Onychomycosis

21 Jul

Onychomycosis, also known as, fungal nail infections affects toenails (more likely) or fingernails. Causing a yellow or white deformed and discoloured presentation. They are not serious in nature but treatment/ management can take time to heal the nail. Most common cause of the fungal infection is Trichophyton rubrum.

- About 10% of the global population has onychomycosis [1]
- Males are more commonly affected by onychomycosis [2]
- Reported mean prevalence in Europe and the US varies between 4.3-8.9% [3]
- In the US point prevalence of fungal nail infection is estimated as 13.8% in adults [4]
- Athletes are 2.5 times more likely to be affected by onychomycosis [5]
- Fungal nail infections are more common in older people [6]
- Warm, dark and moist environments contribute to fungal growth on the nail
- Not keeping feet clean and dry
- Walking in spaces with a high risk of spreading infections [8]
Medical Students
- Commonly triggered by environments like public showers, swimming pools, or locker rooms where people walk barefoot.
- Occlusive footwear creates a dark, moist, warm setting that weakens the hyponychial seal under the nail.
- This disruption allows dermatophytes (fungal organisms) to enter the nail bed.
- Dermatophytes feed on nail keratin, spreading from less visible toes to the sole and nail units.
- Early infection causes low-grade inflammation of the nail.
- If left untreated, it becomes chronic and persistent.
- The nail matrix is secondarily affected—leading to hyperkeratosis, thickening, nail plate distortion, and eventual detachment
Patients
- Nail fungus often starts in places where feet are exposed, like gyms, pools, or shared showers.
- Wearing tight or sweaty shoes creates the perfect conditions (dark, warm, moist) for fungus to grow.
- This weakens the seal under the nail, allowing fungus to get in.
- The fungus grows by feeding on keratin, a substance that makes up nails and skin.
- It spreads from small toes to the bottom of the foot and then to the nail.
- At first, the nail becomes slightly inflamed, but over time it turns into a long-term infection.
- The nail root tries to protect itself by thickening, but this causes the nail to change shape and may lead to it lifting off. [7]
- History of athlete’s foot (tinea pedis)
- History of nail dystrophy (wasting of tissues or defective nutrition to the nail)
- Older age
- Male
- Exposure to spaces/ people with athletes feet or fungal nail infections
- Diabetes
- Peripheral vascular disease- reduced circulation of blood to areas of the body
- Weakened immune system
- Psoriasis
- Damaged nails [1,8]
- Thickened nail
- White, chalky colour discolouration
- Yellow, black or green discolouration of the nail [1]
- Fragile nails
- Cracking in the nails
- Separation of the nail from the nail bed (onycholysis) [9]
- Pain or discomfort
- Brittle nails (pieces may break off) [8]
- Clinical assessment of appearance
- Microscopic examination of sample- to rule out different diagnosis such as psoriasis.
- Culture of scrapings- to find the organism that is causing the fungal infection
- Polymerase chain reaction of clippings- using the distal (furthest point from the toe) part of the toe/ finger nail is preferred
- Histopathologic (using cells) examination with an acid-Schiff (PAS) stain- examination of nail clippings with a PAS stain can confirm the diagnosis [1,9]
- Psoriasis- nail deformation and pitting
- Lichen planus- condition that affects the skin and nails, can become thin and discoloured
- Eczema- nails are irregular and thickened
- Alopecia areata- brittle nails
- Bacterial infections- nail discolouration to black and green
- Viral warts- distorted nail growth
- Onychogryphosis- thickened nails
- Trauma- nail seperates from nail bed
- Yelow nail syndrome- nail discolouration
- Melanoma of the nail (subungual)- discolouration to black and nail distortion [10]
Medical Students
- Most cases are mild or asymptomatic, with low risk of complications.
- Lifestyle advice includes:
  - Cutting nails regularly.
  - Thoroughly drying feet after bathing.
  - Wearing moisture-wicking or absorbent socks.
  - Using antifungal foot powder.
  - Avoiding old shoes that may harbour fungal spores.
- Drug treatment is considered when:
  - History of ipsilateral cellulitis.
  - Patient has diabetes.
  - Symptoms affect quality of life.
  - Psychological distress due to nail appearance.
  - Patient desires cosmetic improvement.
- Oral antifungal agents:
  - Terbinafine
  - Itraconazole
  - These bind to the nail bed and remain effective after discontinuation.
- Newer topical agents (can penetrate nail plate and offer better efficacy):
  - Efinaconazole
  - Tavaborole
Patients
- Many nail infections cause no pain or symptoms, and may not lead to serious issues.
- Helpful lifestyle tips:
  - Trim your nails.
  - Dry your feet well after bathing.
  - Wear socks that absorb sweat.
  - Use antifungal powder on your feet.
  - Consider throwing out old shoes that may carry fungus.
- Medicine may be suggested if you have:
  - A skin infection on the same foot (cellulitis).
  - Diabetes.
  - Pain or discomfort from the nail infection.
  - Emotional or mental stress due to the infection.
  - A wish to improve nail appearance.
- Common oral medications:
  - Terbinafine
  - Itraconazole
  - These stay active in the nail even after you stop taking them.
- Newer treatments (applied to the nail):
  - Efinaconazole
  - Tavaborole
  - These reach deep into the nail and are often more effective. [1]
- Distress to mental health and self esteem
- Difficulty walking, exercising or wearing shoes
- Bacterial infections
- Cellulitis (inflammation of skin)
- Injury to the surrounding skin caused by nail changes
- Mass growing keratin (protein that creates nails and hair) below the nail plate (dermatophytoma)
- Contagious source if living with others [10]
- Fungal nail infections are always minor
- Nail polish will prevent fungal infections
- Soaking your feet in bleach will cure fungal infections
- Poor hygiene causes fungal infections [11]
- Fungal infections can be cured by removing the nail
- Fungal nail infections can be cured quickly [12]
- How can I treat discomfort from the infection?
- Can it spread to others? How can I prevent that from happening?
- How long will it take for treatment to work?
- What can I do if the infection is impacting my self esteem?
- How do I avoid getting an infection again in shared spaces?
- American Academy of Dermatology
- Centres for Disease Control and Prevention
- Canesten.co.uk
[1] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/nail-disorders/onychomycosis?query=onychomycosis
[2] https://pubmed.ncbi.nlm.nih.gov/24283696/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9604567/
[4] https://www.aafp.org/pubs/afp/issues/2021/1000/p359.html
[5] https://pubmed.ncbi.nlm.nih.gov/25409999/
[6] https://bestpractice.bmj.com/info/
[7] https://www.ncbi.nlm.nih.gov/books/NBK441853/#:~:text=Onychomycosis
[8] https://www.nhsinform.scot/illnesses-and-conditions/skin-hair-and-nails/fungal-nail-infection
[9] https://www.cdc.gov/fungal/nail-infections.html
[10] https://cks.nice.org.uk/topics/fungal-nail-infection/diagnosis/differential-diagnosis/
[11] https://kdcclinic.com/blogs/debunking-common-myths-about-toenail-fungus
[12] https://www.bergdpm.com/blog/5-myths-about-treating-toenail-fungus.cfm