Fungal Nail (Onychomycosis) Infections Research Review

Onychomycosis, or fungal nail infection, is a common and tough infection. It affects many people around the world. It is estimated to occur in around 5% of people worldwide (with higher rates in older adults, up to 20–25%) .

Toenails are affected more often than fingernails. Onychomycosis makes up about 30% of all fungal infections in the skin, hair, and nails. Beyond cosmetic concerns, fungal nail infections can cause pain, discomfort, and nail disfigurement, impacting patients’ quality of life. 

In diabetic or immunocompromised individuals, severe nail fungus can even serve as a portal for secondary bacterial infections. This report gives a clear overview of onychomycosis. It covers its causes, effects, and all treatment options. The guidance is based on evidence and is suitable for podiatrists. It is also easy for patients to understand.

Causes and Pathology of Onychomycosis

Distal lateral subungual onychomycosis of the great toenail, showing yellow-white 
discolouration, subungual debris, and partial nail plate detachment.

Onychomycosis is caused by a variety of fungi that invade the nail plate or nail bed. Most cases, about 80% in places like the UK, are caused by dermatophyte fungi. The most common type is Trichophyton rubrum, found all over the world.

Other dermatophytes such as T. mentagrophytes/interdigitale also cause toenail infections. In addition, yeasts like Candida albicans can infect nails. This is more common in fingernails or chronic paronychia. Non-dermatophyte moulds, such as Fusarium, Aspergillus, and Scopulariopsis, can also infect nails sometimes. These non-dermatophyte infections are less common but may be more resistant to standard therapies.

Fungal Spores

Fungal nail infections usually begin when fungal spores enter small cracks in the nail or the surrounding skin. A common source is untreated athlete’s foot (tinea pedis) that spreads into the nail. The fungi digest keratin in the nail, leading to a gradual destruction of the nail structure.

As the infection establishes, the nail typically becomes discoloured (yellow, white, or brown), thickened, and brittle. Debris can accumulate under the nail (subungual hyperkeratosis), and the nail may lift from the nail bed (onycholysis).

There are different types of onychomycosis. The most common type is distal lateral subungual onychomycosis. In this type, the infection starts at the free edge or side of the nail and spreads inward. 

Other forms include white superficial onychomycosis (white chalky patches on the surface of the nail), proximal subungual (starting at the cuticle area, often in immunosuppressed patients), and total dystrophic onychomycosis (complete nail destruction in long-standing cases) . 

No matter the pattern, the main issue is a fungal infection in the nail unit. This infection causes inflammation and leads to the typical changes in the nails.

Risk Factors

Several risk factors predispose patients to onychomycosis. These include advanced age (due to slower nail growth and cumulative exposure), diabetes and peripheral vascular disease (poor circulation to the toes), immunosuppression (e.g. HIV/AIDS or immunosuppressive medications), trauma to the nails, and environmental factors like communal showers or constantly sweaty footwear. 

The infection does not resolve spontaneously and tends to progress, potentially spreading to other nails or to the skin (and vice versa). Early intervention can limit nail damage and improve outcomes.

Clinical Presentation and Diagnosis

Clinically, patients often present with one or more nails that are discoloured (yellow, white, or brownish), thickened, friable, or deformed. They may complain of nails that are difficult to cut, uncomfortable in shoes, or mildly painful if pressure is applied. 

In some cases, the nail can crumble or even detach partially. However, it is important to note that not all nail dystrophies are fungal – in fact, only about 50% of abnormal-looking nails are due to onychomycosis. 

Other conditions like psoriasis, lichen planus, trauma, or nail dystrophy from systemic disease can mimic fungal infection. Therefore, confirming the diagnosis through laboratory tests is recommended before initiating long-term antifungal therapy.

Standard Diagnosis 

Standard diagnostic approaches include obtaining a nail clipping or scraping of subungual debris for a KOH (potassium hydroxide) preparation and microscopy, which can quickly reveal fungal elements if present. KOH prep is quick and highly specific for fungi. A fungal culture of the nail sample can identify the exact organism and help with treatment. For example, it can detect a non-dermatophyte mould that may respond differently to therapy. However, cultures can take weeks and may sometimes give false negative results. 

New techniques like PCR (polymerase chain reaction) can quickly find DNA of dermatophytes. They are very sensitive, but they cost more and are not available everywhere. In practice, many clinicians will confirm onychomycosis with at least a KOH or culture. 

In clear cases with high suspicion, some podiatrists or GPs may start treatment right away. This is especially true if tests are not easily available. However, it is usually better to get lab confirmation first. This helps avoid treating a different nail problem.

Treatment Options Overview

Treating onychomycosis can be challenging due to the nail’s slow growth and the fungus’s protected location under or within the nail. Successful treatment requires eradication of the fungus and allowing a new healthy nail to grow in, which for toenails can take 9–12 months (fingernails about 6 months). 

The choice of therapy depends on the severity of infection (number of nails, extent of nail involvement), the causative organism (if known), patient factors (age, comorbidities, preferences), and prior treatment history.

Often a combination of approaches yields the best result. Below, we outline the main treatment modalities, including clinical (prescription) therapies and accessible non-prescription or natural options. We will then compare their effectiveness, safety, and other considerations.

Oral Antifungal Medications

Oral systemic antifungals are considered the most effective treatment for moderate to severe onychomycosis and are recommended as first-line therapy in most clinical guidelines. 

Because the medication is delivered via the bloodstream to the nail bed, oral therapy can tackle the infection more comprehensively than topical agents, which struggle to penetrate the thick nail plate. 

The two most commonly used oral agents are terbinafine and itraconazole, with terbinafine (an allylamine antifungal) being the drug of choice for dermatophyte onychomycosis  .

Terbinafine (oral):

Terbinafine is highly effective against dermatophytes, working by fungicidal action (it inhibits ergosterol synthesis in the fungus). The standard regimen for toenail infection is 250 mg daily for 12 weeks (for fingernails, typically 6 weeks). 

Terbinafine achieves the highest cure rates among treatments – meta-analyses indicate mycological cure rates around 70–80%, with complete clinical cure (clear nail) in roughly 60–70% of cases depending on study and definition. In head-to-head trials, terbinafine has outperformed itraconazole in achieving sustained cure. For example, one 5-year follow-up study found significantly lower relapse rates after terbinafine (about 21–23%) compared to itraconazole (around 48–53%). 

Terbinafine is generally taken once daily and is relatively convenient. It is also now inexpensive as a generic; one source noted that a 30-day supply in the U.S. can cost on the order of $8–$72, often making it cheaper than topical antifungal lacquers . 

Safety: Terbinafine is usually well-tolerated. The most common side effects are mild gastrointestinal upset or headache. A small percentage of patients may develop skin rashes or taste disturbances. The primary safety concern is potential hepatotoxicity – terbinafine can, in rare instances, cause liver injury. For this reason, it’s contraindicated in patients with active or chronic liver disease, and liver function tests are recommended before starting therapy. 

Routine monitoring during treatment is often not necessary for healthy patients, but many clinicians will advise patients to report any signs of liver issues (fatigue, dark urine, etc.).

Terbinafine also has some drug interaction potential (it can affect the metabolism of certain antidepressants, beta-blockers, etc.), but fewer interactions compared to itraconazole. Overall, for an otherwise healthy adult with multiple toenails involved, oral terbinafine for 3 months is usually the first-line treatment due to its high efficacy and acceptable safety profile.

Itraconazole (oral):

Itraconazole, a triazole antifungal, is the second most commonly used oral drug for onychomycosis. It is particularly useful in cases caused by non-dermatophyte moulds or Candida, where terbinafine might be less effective. Itraconazole can be given in two ways: a continuous daily dose (e.g. 200 mg daily for 12 weeks for toenails) or a pulse regimen (e.g. 200 mg twice daily for 1 week per month, repeated for 3–4 months). 

Pulse therapy is often used to reduce side effects while still achieving good nail penetration. 

Efficacy: Itraconazole has somewhat lower cure rates than terbinafine for dermatophyte infections. A meta-analysis noted mycological cure rates around 59–63% for itraconazole (depending on dosing regimen) . Clinical cure (normal-looking nail) rates in trials range roughly 40–70%. 

Itraconazole is effective for a broader spectrum of fungi (including yeasts), so it is preferred if the infection is proven or suspected to be caused by Candida. Safety: Itraconazole’s main limitation is its side effect and interaction profile. It can cause gastrointestinal upset and, rarely, liver enzyme elevations. 

Importantly, itraconazole can interact with many other medications (it’s a strong CYP3A4 inhibitor), so careful review of a patient’s medications is required to avoid harmful interactions. It is also contraindicated in patients with heart failure (itraconazole can have negative inotropic effects).

As with terbinafine, baseline liver function testing is advisable. Itraconazole is a bit more expensive than terbinafine in many regions (though also available as generic). It remains a valuable option for those who cannot take terbinafine or have non-dermatophyte infections.

Fluconazole (oral off-label):

Fluconazole is not officially approved for onychomycosis in many countries. However, it is sometimes used off-label for yeast infections. A common regimen is 150–300 mg once weekly for 6–12 months. Studies report lower cure rates (around 40–50%) for dermatophyte onychomycosis, so fluconazole is generally a second-line or third-line choice. It may be considered if both terbinafine and itraconazole are unsuitable, or in mild cases where a slow, long-term approach is acceptable.

Its safety profile is similar to itraconazole (monitor liver function, watch for drug interactions).

In summary, oral antifungals, especially terbinafine, offer the highest chance of curing fungal nail infection. They have the advantage of a shorter treatment duration (3 months, versus up to 12 months for topicals) . The drawbacks include potential side effects, drug interactions, and the need for a prescription and monitoring.

They are generally reserved for cases with significant nail involvement or when rapid, definitive treatment is desired. For mild, superficial infections or for patients who cannot take systemic therapy, topical approaches are considered instead.

Topical Antifungal Treatments

Topical antifungal medications are applied directly to the affected nails and adjacent skin. They avoid side effects and drug interactions. This makes them a good choice for patients who cannot take oral therapy or prefer not to use oral medications. Topical treatments are less effective at curing infections. This is mainly because it is hard for them to penetrate the thick nail plate and reach the fungus in the nail bed.

Topical therapy works best for mild to moderate onychomycosis. This includes superficial white onychomycosis or distal infections. These infections should affect less than 50% of a few nails. It can also be used alongside oral therapy. It can also be used as maintenance after oral therapy to prevent recurrence.

Common topical antifungal agents include:

Medicated nail lacquers (polish)

The traditional prescription lacquer is ciclopirox 8% (a hydroxypyridone antifungal), available as a nail lacquer (Penlac* in the US). In Europe and other regions, amorolfine 5% lacquer is widely used. These lacquers are put on the affected nails. This is usually done daily or once or twice a week for amorolfine. They are used for a long time, typically 6 to 12 months. Each week, the built-up layers of lacquer are usually cleaned off with alcohol and the nail is filed, then the cycle continues.

Efficacy: Cure rates with ciclopirox are modest. In clinical trials, about 7% of patients were completely cured after 48 weeks of daily use. This is better than the 1% cure rate with a placebo. In other words, many patients will not get a full cure with lacquer alone, especially if the infection is extensive.

Amorolfine is not available in the US, but it is used in the UK and other countries. It has cure rates of 15–20% when used for 6–12 months. It may work a bit better than ciclopirox for dermatophytes. Some studies show that amorolfine 5% lacquer can achieve a mycological cure in about 40% of cases. Topical monotherapy is usually less effective than oral therapy. Guidelines often recommend it for limited disease or when oral treatments are not suitable. Safety: Topical lacquers are very safe; the worst one might experience is a localised skin irritation or redness around the nail. There are no serious systemic effects because little of the drug is absorbed. Patient compliance can be a challenge – applying a medicine to nails daily for nearly a year, and trimming/filing nails regularly, requires diligence. Podiatrists often emphasise to patients the importance of adherence if they choose topical treatment.

Newer topical solutions

In the last decade, newer topical antifungals have been developed to improve penetration. Two important treatments are efinaconazole 10% solution (brand name Jublia) and tavaborole 5% solution (Kerydin). These are brush-on solutions, not a hard lacquer. They are applied daily for 48 weeks. These have the benefit of not needing nail debridement or product removal. They are more like a medicated liquid that dries on the nail. Efficacy: Efinaconazole has shown better results than older lacquers.

In large trials, efinaconazole had complete cure rates of about 15–18%. This is compared to around 3–5% for the vehicle placebo after one year of daily use. Its mycological cure rates (lab evidence of clearing) were higher, around 50–55% in trials. Tavaborole has slightly lower efficacy: complete cure in roughly 6–9% of patients (vs ~1% with placebo) , and mycological cure around 30–36%. While these percentages are not high, they do indicate that a subset of patients can be cleared with topicals alone. Both efinaconazole and tavaborole required daily application for 48 weeks in studies. 

Safety: These solutions are very safe. The main side effects are mild skin reactions, like redness, dermatitis, or itching around the nail. There are no significant systemic risks. One practical downside is cost and access – these newer topicals can be expensive, and not all healthcare systems subsidise them. In some countries, they may not be available yet or are only available privately. For example, when first introduced, a bottle of efinaconazole could be several hundred dollars (USD), and one course may require multiple bottles. Cost considerations can therefore limit their use, especially given the moderate cure rates.

Over-the-counter (OTC) antifungal preparations

There are many OTC creams and ointments for athlete’s foot. Some people try to use these on their nails. These include clotrimazole and terbinafine cream. However, regular creams do not work well on nails. This is because they do not penetrate deeply enough. There are also over-the-counter nail products for nail fungus. Some of these contain weak glycolic acids, herbs, or low levels of antifungals. However, they usually lack enough clinical data to support their use. If a patient wants non-prescription options, they are often told to try natural remedies. These remedies will be discussed later. They may also be advised to see a professional for stronger treatments.

Adjunctive measures with topical therapy

Whether using lacquers or solutions, combining treatment with mechanical debridement of the nail can improve outcomes. Trimming and filing down the thickened nail reduces fungal load and helps the drug penetrate. Podiatrists often trim the nail during clinic visits. This can help relieve symptoms. Thinner nails cause less pressure pain in shoes and may improve treatment results.

In some cases of thick or stubborn infected nails, the nail plate can be temporarily removed. This can be done surgically or by using urea ointment to dissolve the nail. After removing the infected nail, you can apply antifungal creams directly to the nail bed. This method may work for a stubborn single nail, but most evidence is based on personal stories.

Surgical nail avulsion with topical therapy was used before effective oral drugs were available. Now, it is usually saved for special cases. This includes one severely affected nail in a patient who cannot take oral medication. It can also be used alongside oral therapy in severe cases.

In summary, topical treatments are safe and easy for patients to access. However, they need a long treatment course and have modest success rates for curing conditions. They are appropriate for milder infections and for patients who understand the commitment involved. In many cases, if topical treatment fails or the disease is extensive, transitioning to oral therapy is necessary for better chances of cure.

Laser Therapy

Laser treatment has emerged over the past decade as an attractive-sounding, non-pharmaceutical approach to onychomycosis. In laser therapy, strong light is aimed at the infected nail. This light often comes from Nd:YAG lasers at a wavelength of 1064 nm or from diode lasers. The laser can heat and destroy fungal cells in the nail bed. It does this without harming the nearby tissue.

Lasers can also create micro-pores in the nail that might aid in delivering topical drugs. Treatment typically involves a series of laser sessions (e.g. one session every few weeks, with multiple pulses per nail).

Evidence and efficacy: To date, the evidence for laser therapy is mixed and somewhat controversial. Some small studies and case series reported better nail appearance and even fungal clearance. However, high-quality controlled trials have not always shown these benefits. A 2020 Cochrane review of treatments found no strong evidence. Laser therapy alone is not significantly better than no treatment or fake treatment for curing onychomycosis. In three controlled trials analysed, mycological cure rates with laser were not statistically different from placebo/sham (and in one study, no patients achieved a complete cure with laser, whereas a few did with the sham) . 

Some trials did note temporary improvement in nail appearance (reduced thickness or discolouration) after laser therapy, but this did not always translate to actual eradication of the fungus. On the other hand, a few newer studies have suggested lasers might have some efficacy when used in combination with topical antifungals. 

A 2022 meta-analysis (Zhang et al.) pooled data from 12 trials and found that adding laser treatments to a topical regimen increased the likelihood of clinical improvement and mycological cure compared to topical treatment alone. However, many of those studies were small or had methodological issues (lack of blinding, short follow-up). Another systematic review (2024) noted wildly varying cure definitions and mixed outcomes among laser studies, concluding that more rigorous research is needed.

In practical terms, some podiatry and dermatology clinics do offer laser therapy for onychomycosis, often marketing it as a safe alternative to drugs. Patients attracted to lasers are usually those worried about oral medication side effects or those who have not responded to other treatments.

Have realistic expectations: Laser therapy can improve the nail temporarily. However, achieving high cure rates with this treatment is still difficult. Professional guidelines have been cautious – for instance, the British Association of Dermatologists (BAD) in 2014 noted lasers showed “promising results” but did not recommend them as a first-line treatment due to insufficient evidence. As of 2025, there is still no major guideline that endorses laser therapy as a proven standard treatment for nail fungus, though research continues.

Safety and cost: One advantage of laser therapy is that it is generally safe and well-tolerated. Patients may feel a warming or mild pinprick sensation during treatment. Adverse effects are minimal – occasionally mild pain, nail dystrophy, or transient burns if not done carefully, but serious complications are rare. There is no systemic effect, which is a plus for those who cannot take oral antifungals. The downside is cost: laser treatments are often not covered by insurance/health systems for fungal nails (viewed as aesthetic or experimental), so patients must pay out of pocket.

Multiple sessions can make this expensive. Also, the equipment and practitioner time add to cost. Because of the uncertainty in efficacy, cost-effectiveness is in question.

In summary, laser therapy for onychomycosis is an emerging modality with inconclusive evidence. It may help as an extra treatment or an option for patients who cannot use standard therapies. However, patients should be told that it is not a sure cure and that relapses can happen. Podiatrists and dermatologists who use lasers often combine them with other treatments and monitor results closely. Further large-scale trials are needed to determine optimal laser parameters and true success rates.

Photodynamic Therapy (PDT)

Photodynamic therapy is another innovative approach to treating onychomycosis, involving a chemical photosensitizer and a specific wavelength of light. In PDT, a photosensitising agent (such as 5-aminolevulinic acid [ALA] or methyl-ALA, or even dyes like methylene blue or toluidine blue) is applied to the infected nail and allowed to penetrate. This agent preferentially accumulates in fungal cells or the nail keratin. The nail is then lit with a light source, usually red light or a specific laser. This activates the photosensitizer, which creates reactive oxygen species that kill the fungi. Essentially, PDT attempts to selectively “burn out” the fungus with chemical light activation.

Evidence and efficacy: PDT has been explored in multiple small studies with varying protocols (different photosensitizers, light doses, and treatment intervals). Some reports are promising. For example, a Spanish trial using methyl-ALA with red light reported about 60% clinical cure of treated nails. Another study compared PDT (using a laser light source) to oral fluconazole: after 24 weeks, about 90% of patients in the PDT group responded (showed improvement or cure) versus 40% in the fluconazole group (this was a non-blinded study).

These results suggest PDT can be quite effective in some cases. Patients who did not respond to oral antifungals have sometimes cleared their infections with PDT. This suggests that PDT may help in tough cases. On the other hand, the methodology of many PDT studies has been questioned – some lack control groups or blinding, and sample sizes are small. A systematic review in 2016 found that while many patients experienced improvement, the definitions of “cure” were inconsistent and true mycological cure rates were variable. PDT seems to work best for mild or moderate onychomycosis. Very thick nails can still be a challenge due to limited light penetration.

Practical aspects: A typical PDT plan may involve treating the nail once a week or every two weeks for several sessions. Prior to applying the photosensitizer, the nail is often thinned (e.g. with a urea paste or by drilling small holes) to improve penetration.

The patient soaks the nail in the photosensitizer solution or cream for 30 to 60 minutes. After that, a light is shone on the nail for a few minutes. Multiple nails can be treated. The session can cause some pain or burning in the nail/finger/toe during illumination, which is usually tolerable but sometimes requires a break or cooling spray.

After treatment, nails might be sensitive or red for a day or two. One advantage is the lack of systemic side effects – like laser, it’s a local treatment.

Current status: Photodynamic therapy is still not a mainstream, first-line treatment, but it is a useful alternative for patients who cannot take oral medications or who have failed conventional therapies . It is available in certain specialised clinics. Cost-wise, it tends to be high (multiple sessions with special equipment and drugs), and like lasers, it is often not reimbursed by insurance.

More research is ongoing to optimise PDT protocols for nail fungus. Recent literature and expert opinions view PDT as promising but needing further validation  . For podiatrists, PDT could be considered in recalcitrant cases or when other treatments are contraindicated, keeping in mind patient preference and cost.

Non-Prescription and Natural Remedies

Due to the often prolonged and costly nature of prescription treatments, many patients inquire about natural or over-the-counter remedies for fungal nails. A number of alternative treatments have been tried, with varying degrees of anecdotal or preliminary evidence.

While these approaches tend to have lower proven efficacy than medical treatments, they can be accessible and have minimal side effects, which is appealing to some patients. Podiatrists can play a role in guiding patients on the realistic expectations from such remedies. Here we discuss some popular non-prescription options:

Tea tree oil (Melaleuca alternifolia)

Tea tree oil is an essential oil with known antifungal properties. It’s one of the most commonly recommended natural remedies for onychomycosis. A well-known double-blind trial compared 100% tea tree oil to a 1% clotrimazole solution.

Clotrimazole is an antifungal medication used to treat toenail fungus. After 6 months of daily use, the cure rates were 18% with tea tree oil and 11% with clotrimazole. This difference was not statistically significant. About 60% of each group had partial or full clinical improvement in nail appearance. This suggests tea tree oil might have a mild to moderate antifungal effect, roughly similar to a low-strength medicated cream.

Patients in both groups also performed nail debridement, which likely contributed to improvement. Tea tree oil is applied typically twice daily to the affected nail. Safety: It is generally safe topically, but it can cause skin irritation or allergic dermatitis in some individuals. Advise patients to stop if marked redness or itching develops around the toe.

Tea tree oil may be worth trying for very mild cases or as an extra treatment. However, patients should know that cure rates are much lower than those of prescription therapies.

Vicks VapoRub (mentholated ointment)

Vicks contains menthol, camphor, and eucalyptus oil, which have some antifungal activity in vitro. There have been small studies and many anecdotal reports of Vicks improving nail fungus. In a small trial, using Vicks VapoRub daily for 48 weeks led to a 28% complete cure. There was also a 56% partial improvement in patients' nails. This study did not have a control group.

While no robust evidence, some podiatrists consider Vicks a harmless home remedy that might help slow fungal growth. The ointment should be applied to the nail and under the tip if possible, daily or twice daily. Safety: minimal, aside from possible minor skin irritation. It has a strong smell, which some patients mind and others find reassuring (“medicated” smell).

Vinegar soaks

Vinegar (acetic acid) creates an acidic environment that is unfavourable for fungal growth. A common home remedy is to soak your feet daily in a vinegar solution. Mix one part white vinegar with two parts warm water. Soak your feet for 15 to 20 minutes. This can inhibit fungal proliferation and possibly improve the appearance of the nail over time.

Vinegar may not completely get rid of a nail infection by itself. However, some patients say it helps stop the infection from getting worse. It’s cheap and readily available. Safety: Vinegar is safe when it is properly diluted. Strong vinegar can irritate or burn the skin. Use it carefully and make sure to dilute it enough.

Other essential oils and natural extracts

Oregano oil (containing thymol), lavender oil, and oil of bitter orange have all shown antifungal activity in lab studies. Some people apply these to their nails daily. Vitamin E has been anecdotally used to soften nails and possibly improve nail health in combination with antifungals. There is also anecdotally successful remedy involving applying garlic (which has antifungal allicin) to the nail or using Listerine mouthwash soaks (which contain thymol and menthol). Scientific support for these is weak, but they likely do no harm if used safely.

Overall, these integrative medicine methods have shown some antifungal effects in small studies. However, there are not many large, thorough trials. Therefore, their effectiveness is not clearly established, and cure rates are generally low. They might be considered for very mild cases, for patients who absolutely cannot take other therapies, or as adjuncts to standard treatment to possibly enhance results.

Podiatrists should make sure patients know that natural remedies often need to be used regularly for many months. Even then, the fungus might still stay. On the plus side, these remedies are inexpensive and have minimal systemic risks. If a patient wishes to try them, it’s reasonable to allow a trial period (e.g. 3–6 months) and then reassess the nail – if there’s no improvement, they should be guided toward more effective treatments.

Comparing Treatment Effectiveness, Safety and Compliance

Each treatment modality for onychomycosis has its own profile of effectiveness, cost, likelihood of recurrence, and patient compliance considerations. Below is a comparative summary:

Effectiveness:

Oral antifungals, especially terbinafine, have the best cure rates. They often achieve a mycological cure in about 70–80% of cases. Clinical cure is seen in over 50% of cases. Topical prescription treatments have much lower cure rates. For example, efinaconazole can completely cure about 15–20% of patients. In contrast, older ciclopirox lacquer cures only around 7%.

Laser and photodynamic therapies have not consistently shown cure rates like those of oral medications. Some patients may improve, but a reliable cure is not guaranteed. Natural remedies usually work the least well. They may slightly improve appearance or symptoms, but they rarely cure anything. Studies show true cure rates are often below 20%.

Safety:

Topical and device therapies have the best safety profiles, since they largely avoid systemic exposure. Orals have known risks (e.g. hepatic effects with terbinafine or itraconazole), but these are infrequent and can be mitigated by patient selection and monitoring. Lasers and PDT are local interventions; lasers might cause temporary nail or skin injury if applied improperly, and PDT can cause some pain during treatment, but serious adverse events are rare. Natural products are generally safe, though allergic reactions (tea tree oil, for instance) can occur.

Cost:

This can vary by region and healthcare system. In many places, oral terbinafine is a cost-effective option. It is available as a cheap generic. A 3-month course may cost less than a year’s supply of topical lacquer. New topical solutions like efinaconazole can be very costly, often hundreds of dollars or pounds. If insurance does not cover them, the price can be a barrier.

Traditional lacquers (ciclopirox, amorolfine) are moderate in cost (often on the order of 20–50 GBP per bottle, with several bottles needed over a year). Laser and PDT are usually the most expensive options, since multiple specialist sessions are required and insurance coverage is uncommon; total costs can reach hundreds to thousands in private clinics. Home remedies are low cost (a few dollars for a bottle of tea tree oil or vinegar).

It’s worth noting that cost doesn’t always correlate with efficacy in this case – some expensive options (laser) might yield less success than a cheap pill (terbinafine).

Recurrence:

Onychomycosis has a notorious tendency to recur. Even after successful treatment, patients can still get re-infected. This can happen from fungal spores in shoes, the environment, or untreated tinea pedis. Overall relapse rates are estimated to be around 20–25% within 2 years of successful therapy, but can be higher if preventive measures aren’t taken.

Oral terbinafine works well because it kills fungi and stays in the nails for months. This leads to longer-lasting cures than itraconazole. In a 5-year study, relapse rates were about double with itraconazole. Topical treatments, if they do achieve a cure, might have recurrence rates similar to or higher than oral, but data is limited. 

Laser/PDT recurrence rates are not well established; given that many patients were not fully cured to begin with, true recurrence vs incomplete treatment is hard to discern. 

Natural remedies likely have a high recurrence or persistence rate, since they rarely eradicate the fungus completely. A key strategy to reduce recurrence is to address predisposing factors and consider prophylactic measures (see Prevention below). One study showed that using a topical antifungal on the nails twice weekly after finishing terbinafine dramatically reduced recurrence (33% recurrence with prophylaxis vs 76% without after 3 years). This underscores that maintenance therapy can be beneficial, especially for high-risk patients.

Patient compliance:

This varies greatly by treatment. Oral therapy is quite simple. It involves taking a daily pill for 6 to 12 weeks. Most patients follow this well. However, some may stop taking the medication. This can happen if they have side effects or need to do blood tests. Topical therapy requires a lot of daily effort and patience. You need to apply medicine every day for a year. Sometimes, you may not see any visible improvement for months. This can make people stop the treatment. Indeed, lack of adherence is a known factor in topical treatment failure. Patients need encouragement and possibly interim debridements to stay on track.

Laser therapy needs patients to go to several clinic appointments. People usually stick to it if they have paid for a treatment package. However, some may stop coming if they do not see any improvement after a few sessions. Photodynamic therapy also requires regular visits, but the number of sessions is usually predefined.

Natural remedies, like daily soaks or oils, need commitment. These methods are often self-directed, so patients may not be consistent. This is especially true if they do not see quick results. In all cases, setting realistic expectations and having follow-up checks can help improve compliance. For example, a podiatrist who sees a patient every 2 to 3 months can treat the nail by trimming or debriding it. This also helps reinforce the importance of continuing therapy.

The following table summarises the comparison of various treatment types:

(Sources: cure rates from clinical studies; recurrence data from studies and reviews. Cost and compliance are generalised from typical use and expert opinion.)

Recurrence, Antifungal Resistance, and Prevention Strategies

Even after successful treatment, fungal nail infections can recur. Recurrence can happen if you get reinfected from the environment or nearby skin, like with athlete’s foot. It can also occur if the first infection was not fully treated. Studies show relapse rates of roughly one-fifth to one-quarter of cases within two years after clearing the nails. 

Some factors associated with higher recurrence include older age, nail trauma, diabetes, poor peripheral circulation, and not fully eliminating fungus from shoes or skin . If tinea pedis (foot fungus) is not treated, it can stay in the area and reinfect the new nail. The type of treatment used can affect how often the problem comes back. Terbinafine kills fungi and stays in the nail longer, which may lead to a longer period without symptoms. In contrast, treatments that only stop fungi from growing or incomplete courses may allow the fungi to return. As mentioned, itraconazole-treated nails have shown higher relapse in long-term follow-up than terbinafine-treated nails .

Another emerging issue is antifungal resistance. Dermatophytes, especially T. rubrum, have begun to show resistance to terbinafine in some parts of the world. 

Some cases of onychomycosis do not respond to a proper course of terbinafine. Lab tests show that the fungus has mutations in the squalene epoxidase gene, which makes it resistant to the drug. Terbinafine-resistant strains are still rare, but they are being reported more often. This is likely due to the drug's widespread use over the years.

If a patient does not respond to terbinafine treatment, even with confirmed adherence, consider resistance. This is especially true if lab tests still show T. rubrum growth. In such cases, switching to itraconazole or another antifungal, or using combination therapy, might be necessary.

Resistance in onychomycosis is not as common as antibiotic resistance in bacteria. However, doctors should stay alert. It’s important to know that non-dermatophyte molds can be “resistant.” This means that terbinafine or itraconazole may not work well against them. Identifying the organism can help choose a better treatment. For example, Scopulariopsis often does not respond to terbinafine. Candida nail infections may respond better to itraconazole or fluconazole instead.

Preventing recurrence (and initial infection) is a key part of management that podiatrists should emphasise to patients. Important prevention strategies include:

By teaching patients about these preventive steps, podiatrists can help keep feet fungus-free after treatment. This may also stop new infections. Prevention is truly an ongoing effort – onychomycosis can recur, but vigilance in foot care can greatly mitigate the risk.

Conclusion

Fungal nail infections are a globally prevalent problem that can be persistent and frustrating for both patients and clinicians. Understanding the causes and effects of onychomycosis is important for good management. This explains why treatment can take a long time and why it often comes back. Fortunately, there are multiple treatment options available.

Oral antifungal medications are key for getting the best cure rates, especially for severe infections. Topical treatments are a safer, though less strong, option for milder cases or ongoing care. New technologies like laser and photodynamic therapy provide new options. This is especially true for patients who cannot take systemic drugs. However, their role is still being defined.

Moreover, accessible home remedies have a place in patient care when used with realistic expectations and proper guidance. Each approach has pros and cons regarding effectiveness, safety, cost, and convenience. These factors must be balanced with the patient in mind. This often happens through shared decision-making between the podiatrist (or dermatologist) and the patient.

For podiatrists, it is important to stay updated with current research and guidelines, as onychomycosis management continues to evolve. Patient education is very important. It helps explain why treatment takes time. It also shows why sticking to the plan is crucial. Finally, it teaches how to prevent reinfection. All these steps are key to a successful outcome.

A complete plan that includes therapy, extra treatments, and preventive care can help manage tough fungal nail infections. This can lead to clearer nails and a better quality of life for patients.

Sources: Peer-reviewed studies, clinical guidelines, and expert reviews were referenced in compiling this report, including Cochrane reviews, dermatology association guidelines, and recent meta-analyses and trials on treatments for onychomycosis.