Nail: – Nail is the hard part of the body present on each finger’s back and toes fingers at its outer end in most of the primates. The nail has three main parts, i.e., root, plate, and free margin. The nail has a plate-like, translucent structure made up of a tough protective protein called alpha-keratin. Nail helps in protecting the fingertip and surrounding soft tissues from injuries. Nail allows counter-pressure on the pulp of the finger, thus help in delicate movements of the fingertips. 
In this document, Section-1 will discuss Fungal nail infection definition, types, causes, and diagnosis of fungal nail infection. Section-2 will discuss various treatment options for fungal nail infection. Section-3 will be emphasizing on the problem associated with currently available treatment.
Section-1: Fungal Nail Infection (Onychomycosis)
Onychomycosis (also called Tinea Unguium) is a common condition that starts as a white or yellow spot under the tip of a nail and makes the nail brittle, discolored, and crumble at the edge as the infection goes more in-depth. It may involve any component of the nail unit, including the matrix, bed, or plate. Toenail fungal infection is more common than fingernail fungal infection. Overgrowth of fungi causes fungal nail infection. Fungi thrive in warm, moist environments; thus, fungi will overpopulate in this environment.
Onychomycosis treatment’s largest market is North America, and the Asia Pacific is the fastest-growing market. The onychomycosis treatment market is expected to register a CAGR of 6.5%. The prevalence rate of onychomycosis has been 23% across Europe and 20% in East Asia. Onychomycosis incidence is up to 14% in North America, with fungal infection responsible for 50% of all nail disease.
Section-1.1: Types of Fungal Nail Infection
- Distal or lateral subungual onychomycosis
- White superficial onychomycosis
- Candidal onychomycosis
- Endonyx onychomycosis
- Proximal subungual onychomycosis
- Total dystrophic onychomycosis[4,5]
Section-1.2: Causes of Fungal Nail Infection
Dermatophytes:- Dermatophytes such as Trichophyton rubrum and Trichophyton mentagrophytes cause 85-90% of all cases. These are highly resistant and can survive for a more extended period in moist and dark environments.
Non-Dermatophyte Moulds:- It is responsible for 2-5% of all cases. The main species of this category are Scopulariopsis, Scytalidium, Aspergillus, Fusarium, and Acremonium.
Yeasts:- Candida species cause 5-10% of all cases and affect fingernails more often than toenails.[4,5]
Section-1.3: Diagnosis of Onychomycosis: Identifying the causative fungus before starting the treatment is essential because some drugs are more effective against specific organisms than others. Methods used for the diagnosis of onychomycosis are as follows:
- Specimen Collection
- Direct microscopy
Section-2: Treatments For The Nail Fungal Infection
Section-2.1: Non-Prescription Treatments:- These treatments can be taken without a doctor’s prescription and might work well.
- Over-The-Counter Remedies: – Antifungal creams and lotions available in local pharmacy shops can be taken without a prescription. But most often, they are not as effective to treat infection, and infection can reoccur sometime.
- Mentholated Salve: – According to some research, Mentholated salve like Vicks, VapoRub can treat fungal infection by applying a swab on the nail every day.
- Snakeroot Extract: – It is a natural antifungal from the Sunflower family and sometimes used as a prescription antifungal cream.
- Tea Tree Oil: – Due to natural antiseptic characteristics, it can help eliminate fungal infection by applying twice a day to affected nails.
- Listerine or Vinegar: – By soaking the nail 5 minutes a day, it will help dry out the affected nails.
- Oregano Oil: – Thymol is present in oregano oil, which has antifungal properties, thus sometimes combined with tea tree oil in treatment.
- Ozonized Oils: – Studies show that sunflower oil and olive oil should benefit in treating nail fungal infection because these are infused with the same gases present in the ozone layer.
- Vicks VapoRub: – Study suggests that it could be beneficial in nail fungus treatment.
Section-2.2: Topical Treatments for Fungal Nail Infection
Due to the nail anatomy’s compact and hard nature, penetration can be low; thus, Creams and other topical medications are not effective against Onychomycosis. A nail lacquer has been approved for the treatment of nail fungus infection. Currently, Ciclopirox and Amorolfine lacquers are available in the market, which is an effective treatment and prevention of nail fungal infection. These compositions form a hard, clear, and water-resistant film that contains the antifungal agent. The film is effective in the treatment and resistant to multiple washings.
Ciclopirox (Penlac 7%) Nail Lacquers: Ciclopirox inhibits fungal nutrient uptake and thus reduces protein synthesis by depleting amino acids and nucleotides. Adverse effects such as periungual erythema and erythema of the proximal nail fold are most frequently reported in patients who use the preparation.
Amorolfine (5%) Nail Lacquers: Amorolfine inhibits sterol biosynthesis and thus disrupts the fungal cell membrane, leading to cell death. The solvent evaporates and leaves a highly concentrated occlusive film of amorolfine on the nail on applying lacquer preparation. Adverse reactions that occur most frequently are itching, burning, erythema, and scaling. [8,9]
Other topical drugs that are effective in nail fungus infection are
- Efinaconazole (Jublia)
- Naftifine (Naftifin)
- Tavaborole (Kerydin)
- Terbinafine (Lamisil)
Indications For Topical Monotherapy Include:-
- Matrix area is not involved
- 3 or 4 nails are involved, and involvement is lesser than 50% of the nail plate.
- Superficial white onychomycosis (SWO)
- As prophylaxis in patients at risk of recurrence.
Section-2.3: Oral Therapies for Fungal Nail Infection
Griseofulvin, terbinafine, itraconazole, and ketoconazole are the most commonly used drugs for nail fungal infection treatment. The treatment cure rate is approx. 60-80% and medicines need to be taken for a more extended period. Oral therapy is more effective than topical treatment. Oral therapies are not appropriate for the elderly and people on polypharmacy because of higher side effects. Griseofulvin is mostly used in the oral category compared to other drugs, but it is not very effective against toenail fungal infection. Ketoconazole requires once a week for several months and has side effects like skin rash, GI disturbance, and headache. Terbinafine dosage period is daily for eight weeks for fingernail and 12 weeks for toenail fungus infection. Itraconazole dosage period is one week per month for 2 or 3 months and can interact with drugs like antibiotic erythromycin or asthma medications. People with liver disease and congestive heart failure disease are recommended not to take these medications.
Oral therapy is recommended when: –
- Matrix is involved
- Greater than 50% involvement of the distal nail plate.
- Topical drug penetration is less.
Section-2.4: Other Treatments for Fungal Nail Infection
- Laser Treatment:- Stubborn fungus can be destroyed by applying a high dose of light. Some in-vitro studies show that laser treatment has a higher success rate in nail fungal infection treatment. The U.S. Food and Drug Administration already approved several neodymium: yttrium-aluminum-garnet (Nd:YAG) laser therapies for onychomycosis treatment. The Pinpointe Foot-laser, Cutera GenesisPlus laser, and Cooltouch Varia laser are short-pulse laser systems, whereas the Light Age Q-Clear laser is a Q-switched laser. Dual-wavelength near-infrared laser (Noveon) is another laser treatment approved for dermatological use, but not specifically for nail fungal infection treatment. Laser treatments are expensive.
- Photodynamic Therapy:- Photosensitizing drugs and light shows some success in destroying fungal cells to treat nail fungal infection.
- Nail trimming and debridement:- This physical treatment therapy performed simultaneously with other treatments. Study shows that debridement with oral terbinafine had a higher cure rate than terbinafine alone. The cure rate is 77% higher in debridement with ciclopirox concurrent administration compared to ciclopirox alone.
- Sequential therapy:- It involves the combined use of two oral antifungal drugs with a different mechanism of action. It will result in a reduction of treatment duration and cumulative drug exposure to each antifungal. Eg.: 2 doses of itraconazole followed by one or two doses of terbinafine.
- Boosted oral antifungal treatment and boosted topical antifungal treatment:- These therapies are designed to target dormant chlamydospores and arthroconidia within the nail plate to produce sensitive hyphae which are less refractory to antifungal therapy. The risk associated with this therapy is over-stimulation and systemic spread of fungi that are not susceptible to antifungal agents; thus, they are not widely accepted.
Section 3: Problems Associated With Nail Fungal Infection Treatment
Section-3.1: Therapeutic Failure:- Lack of diagnostic accuracy, wrong choice of antifungal or mode of delivery, dormant conidia presence, sequestrated mycelial pockets or resistant fungal species, or lack of consistent penetration are some attributes that are responsible for treatment failure.
Section-3.2: Relapse:- Recurrence of the nail fungal infection is another problem associated with the treatment therapy. Factors related to relapse are age, genetic factors, the extent of initial disease, and comorbid conditions such as diabetes and immunosuppression. 
Conclusion:- Nail is the hard part of the body present on the back of the fingers and helps protect fingertips from injuries. Fungal nail infection is a common condition that will occur mainly due to dermatophytes, non-dermatophyte moulds, and yeasts. Warm and moist environments are the most favorable condition for the fungal infection to occur. Home remedies such as oregano oil, tea tree oil, mentholated oil, etc. effectively treat nail fungal infection. Medicated nail lacquers as topical preparation and oral antifungal drugs are used nowadays for treatment purposes. Laser therapy, Photodynamic therapy, Sequential therapy, and Boosted oral antifungal therapies can also be used to get rid of the fungus.
- Nail Diseases: Causes, Symptoms, Treatment- Antifungal Medications, Antibiotics, Laser
- Fungal Nail Infection: Causes, Treatment, Home Remedies, Symptoms, Prevention
- Nail-Patella Syndrome: Causes, Symptoms, Diagnosis, Treatment
- Toenail Fungus: Causes, Symptoms, Risk Factors, Treatment, Home Remedies, Complications
- Symptoms and Treatment of Nail Pitting or Pitted Nail
- Why do Toenails Smell So Bad & How to Get Rid of Smelly Toenails?
- Myths & Truths about Nail Care & Easy Tips For Having Stronger Nails