Understanding What Causes Nail Fungus and Symptoms of Nail Fungus.
What Is Nail Fungus? Causes, Symptoms, and Early Warning Signs
What Is Nail Fungus? Causes, Symptoms, and Early Warning Signs
Author: H.B. / Published: June-27-2025
When it comes to nail fungus causes, infection doesn’t come from just one type of nail fungus-and that’s a big reason why many nail fungus treatments fail.
There are several types of fungi grouped under onychomycosis, which cause nail fungus — and some are harder to treat than others.
The most common nail fungus invaders include fungal strains like Trichophyton, Microsporum, and Epidermophyton, which frequently infect both fingernails and toenails.
These fungi aren’t just stubborn — they’re adaptive. Meaning they can adapt to antifungal formulas, which makes traditional nail fungus treatments less effective.
This is why the best nail fungus treatment must do more than attack the infection — it needs to disrupt the fungus’s ability to adapt to the nail fungus treatment while actively supporting the regrowth of a healthy nail. That’s the key to having clear nails again.
Nail Fungus Causes:
What Really Triggers the Infection
Nail fungus infection typically originates from contaminated environments and enters through small cracks or nail injuries. It can result from walking barefoot in public showers, using unsanitary bathrooms, wearing tight or sweaty shoes, or being exposed to contaminated tools during a manicure.
While poor nail hygiene isn’t always the cause, it can make the nail more vulnerable — especially if the immune system is already compromised.
Most Common Types of Nail Fungus (Onychomycosis)
What’s Really Invading Your Nails?
Not all nail fungus is the same—nor can it be treated the same. And that matters, because if you’ve been using a “one-size-fits-all” traditional nail fungus treatment, there’s a good chance you’ve been treating the symptom, not the real problem.
Why This Matters:
Most antifungal treatments only focus on surface-level symptoms or a single type of fungus. But there are three major types that can infect and damage your nails—and if your nail fungus treatment doesn’t target all of them, your damaged nail may never fully recover.
That’s why ZanaQuick uses a broad-spectrum, anti-adaptive formula designed to target all three fungal types—before they mutate, spread, or grow resistant.
Here are the most common fungal invaders that affect your toenails and fingernails:
Caused by Dermatophyte Nail Fungus (Trichophyton)
Most common cause of toenail fungus—over 90% of cases, especially in adults
Where it strikes:
Mostly toenails, but can also affect fingernails in some cases
How it attacks:
This fungus invades from underneath the nail tip and slowly works its way upward
What it does:
It thickens, discolors, and crumbles the nail—often leaving it brittle, distorted, or detached
Why it’s difficult to eliminate without the right treatment and method:
These fungi are smart. They adapt quickly and build resistance to common antifungal treatments, making most nail fungus products fail before the job is done.
Because of how common and difficult they are to eliminate, dermatophytes remain the leading nail fungus cause in adults today
Key species in the Trichophyton family include:
- Trichophyton rubrum – the most common, chronic, and stubborn
- Trichophyton mentagrophytes – more aggressive and spreads rapidly
- Trichophyton tonsurans – often linked to fingernail infections and spreads through contact (shared tools, gyms, nail salons)
Caused by Non-Dermatophyte Molds (The Silent Saboteurs)
A less common, but increasingly recognized cause of nail fungus—especially in damaged or aging nails
Where it strikes:
Can affect both toenails and fingernails, often after nail trauma or chronic nail conditions. In cases where trauma or preexisting damage is involved, a non-dermatophyte mold may become the primary nail fungus cause.
How it attacks:
These molds invade through cracks or weakened areas in the nail plate.
What it does:
Causes streaks, discoloration (often green, brown, or black), and leaves the nail crumbly, rough, or distorted in shape
Why it’s difficult to eliminate without the right treatment and method:
Non-dermatophyte molds are often misdiagnosed—and many treatments aren’t designed to target them. As a result, they may not respond to standard antifungals, allowing the infection to continue spreading beneath the nail.
Common species include:
- Fusarium – linked to nail infections following injury or contamination
- Scopulariopsis brevicaulis – often found in older adults or post-trauma nails
- Aspergillus – can create dark, brittle patches and spreads under poor hygiene or moisture conditions
- Acremonium spp. – rare but aggressive; often found in damaged toenails and difficult to treat with standard antifungals. When the right antifungal is not used. chemicals
Caused by Yeast Fungus (Candida – The Moisture-Lover)
A less common, but highly irritating nail fungus cause is yeast fungus, especially Candida species. In contrast to molds and dermatophytes, yeast infections are a lesser-known nail fungus cause but can still be quite aggressive.
Where it strikes:
Primarily fingernails, but can affect toenails in damp or sweaty environments
How it attacks:
Yeast fungi like Candida albicans thrive in warm, moist conditions, often entering through tiny cuts or inflamed skin around the nail
What it does:
It often starts with redness and swelling near the nail fold. In some cases, the area becomes tender or filled with pus—and over time, the nail may discolor, lift, or separate from the nail bed completely.
Where it comes from:
Unlike other nail fungi that only invade from the outside, Candida can come from both external exposure and internal overgrowth. It naturally lives on your skin and inside your body—but under the right (or wrong) conditions, it can flare up and infect the nail
Why it’s difficult to eliminate without the right treatment and method:
Yeast infections are often mistaken for skin irritation or bacterial issues, leading to ineffective treatment. Standard antifungals may fail if they aren’t designed to target Candida specifically, giving the infection time to worsen.
Most common species:
- Candida albicans – thrives in moisture and can overgrow during illness, frequent handwashing, or immune imbalance
- Other Candida species – may also infect nails in healthcare workers or those with chronic exposure to water or cleaning chemicals
Does Nail Fungus Really Come from Within The Body?
There is a common misconception that nail fungus comes from within your body, particularly from your blood. In reality, nail fungus (onychomycosis) is typically an external infection. It occurs when fungi like dermatophytes, yeasts, or molds invade the nail through small cracks, injuries, or areas of damaged skin.
Recognizing Early Signs of Nail Fungus
Nail fungus often starts small — like a faint white or yellow spot near the edge of your fingernail or toenail.
But don’t ignore it — this seemingly minor issue can quickly escalate. As the fungal infection spreads, your nails can become thick, discolored, brittle, or even start crumbling at the edges. In more advanced cases, the nail may lift, break, or lose its shape entirely.
Catching these signs early is key, because the sooner you start using an effective nail fungus treatment, the better your chances of rescuing the damaged nail as soon as possible.
Discoloration (yellow, white, green, or brown)
Thickening or brittleness
Crumbling edges
Nail lifting or separating
Redness, swelling, or pus around the nail (especially in yeast infections)
Bad odor
Nail growing in distorted or uneven
Discoloration (yellow, white, green or brown)
Thickening or brittleness
Crumbling edges
Nail lifting or separating
Redness, swelling, or pus around the nail (especially in yeast infections)
Bad odor
Nail growing in distorted or uneven
If left untreated, any nail fungus cause—whether dermatophyte, mold, or yeast—can result in permanent nail damage.
How to Identify Nail Fungus?
No test is perfect. Even lab tests can miss infections—especially if the fungus isn’t active, or if the sample isn’t collected correctly. That’s why many doctors rely on a combination of visual symptoms, patient history, and test results to decide how to treat it.
A lab test is most helpful when previous treatments have failed or the infection looks unusual.
Most Common Type of Test for Nail Fungus?Since each nail fungus cause presents differently, the right test can help confirm what kind of treatment works best. Here are the three most common…
KOH Test (Potassium Hydroxide Prep)
How is the procedure?
The nail is gently trimmed, and a portion is placed in a potassium hydroxide solution before being checked under a microscope for signs of fungal cells. It’s a quick way to check if it’s nail fungus, but it won’t always reveal the specific type of fungus.
Where is this test done?
This test isn’t commonly done at regular doctor’s offices, but some dermatologists or podiatrists may offer it right in their clinic during your visit
When will you get the results?
You’ll usually get the results the same day, since the analysis is done in-office.
How accurate is it?
The results are accurate about 60% to 80% percent of the time, depending on how the sample is collected and the fungal load.
How reliable is it?
This type of test can miss low-level infections, and sometimes it confuses nail debris or skin cells for fungal elements
How much does it cost?
Expect to pay anywhere from $15 to $50 for the test itself. Not including the provider’s consultation fee.
Does the insurance cover it?
Some Insurance companies may help with the cost if the test is considered medically necessary, but coverage policies differ widely.
Fungal Culture
How is the procedure?
The nail is gently trimmed and the small pieces of the affected nail are sent to a lab. This helps identify the specific nail fungus causing the infection, but the process takes longer than other methods.
Where is this test done?
It’s usually ordered by a dermatologist, podiatrist, or primary care provider. After the doctor cuts the nail, he/she will send the samples to the lab to get tested for nail fungus.
When will you get the results?
You’ll usually get the results in approximately 1 to 3 weeks.
How accurate is it?
The results’ accuracy ranges from 50% to 70%, but it’s highly dependent on the sample quality and whether the fungus is viable enough. Because the accuracy depends on whether the fungus is alive, this test may not always pinpoint the exact nail fungus cause.
How reliable is it?
This type of test can sometimes give false negatives—meaning that no nail fungus is detected, even if an infection is present.
How much does it cost?
Expect to pay anywhere from $50 to $150, depending on your provider and the lab’s fees. Not including the provider’s consultation fee.
Does the insurance cover it?
Some Insurance companies may help with the cost if the test is considered medically necessary, but coverage policies differ widely.
PCR Test (DNA-Based Test)
How is the procedure?
The damaged nail is gently cut, and the small pieces of nail are sent to a specialized lab, where the nail sample is analyzed using polymerase chain reaction (PCR) technology.
Where is this test done?
The PCR testing is typically provided by an advanced dermatology or podiatry clinic.
When will you get the results?
You’ll usually get the results in approximately 2 weeks.
How accurate is this test?
The PCR test is 90% percent accurate. It’s the most accurate nail fungus test available.
How reliable is it?
While this type of test is highly reliable, sometimes it can detect “dead” fungus organisms that are no longer active.
How much does it cost?
Expect to pay between $150 and $300 or more, depending on your provider and the lab’s fees. Not including the provider’s consultation fee.
Does the insurance cover it?
In most cases, insurance plans do not cover PCR nail fungal tests, but coverage policies differ widely. The patients often pay out-of-pocket money.
What If You Don’t Get Tested?
Most people don’t need lab tests to begin nail recovery. In fact, many doctors diagnose nail fungus based on appearance and symptoms alone. That’s why first using an antiadaptive treatment that targets all three types of nail fungus mentioned earlier—with a proven system like ZanaQuick—can be the smartest step forward, even before testing.
Don’t Wait Too Long to Treat Nail Fungus
Many people wait too long to treat nail fungus, and this delay can make the problem much worse. The longer you wait to use a nail fungus treatment, the longer it will take for your nails to grow back clear and strong.
No matter the nail fungus cause, delaying treatment allows the infection to take deeper hold.
Some minimize the problem, letting time pass without using an effective nail fungus treatment, while the nail condition worsens.
Others rely on home remedies that prove ineffective, allowing the infection to spread.• And some believe that only doctors can offer a treatment for nail fungus, and lack the time for frequent doctor visits.
If you don’t have time to visit a doctor regularly, starting an antiadaptive nail fungus treatment at home — which is the best treatment for nail fungus - following the same approach used by professionals (without relying on oral medications) — can be a smart move.
If you don’t see visible improvements within 6 to 12 months for a toenail and 3 to 6 months for a fingernail, it may be time to consult a doctor to confirm the nail fungus diagnosis or explore other possible causes.
If you still think prescription treatments are the only way,
Then read this first.
It’s easy to unknowingly make the mistake of putting off the nail fungus treatment — or delaying a doctor visit because of time, cost, or the belief that only prescription treatments can fix nail fungus. But the truth is, the more you wait, the longer it will take for your damaged nail to recover.
NAIL FUNGUS PRESCRIPTION TREATMENTS AREN'T THE ONLY EFFECTIVE OPTION
Even if the infection seems stubborn, most toenail fungus cases can still clear up at home when treated with the right nail fungus treatment and the right antiadaptive strategy.
Especially if you use an antiadaptive fungal nail strategy. For example, the ZanaQuick System follows the same strategic principles podiatrists use — targeting the nail fungus while protecting the new nail as it grows.
If it works for you, great. And if it doesn’t fully help resolve your case, you’ll be in a much better position to consult your doctor with a head start and visible progress already in motion.
Conclusion: Achieving and Maintaining Fungus-Free Nails
Clearing nail fungus isn’t just about applying an antifungal product — it’s about choosing the right approach, the best nail fungus treatment, and staying consistent until the nail grows out completely clear and healthy.
Whether you’re just looking for an effective nail fungus treatment or concerned about the fungus coming back, remember this: the right strategy makes all the difference.
Starting with an antiadaptive system like ZanaQuick gives your damaged nail the best chance to fully recover while helping prevent the nail fungus from adapting or returning.
Nail fungus is persistent; it adapts to antifungals. But it’s not unbeatable. The key is disrupting the nail fungus adaptation effect.
Even when you don’t know the exact nail fungus cause, what matters most is choosing the right treatment strategy to clear it.
That’s how you outsmart it. And that’s exactly what an antiadaptive nail fungus treatment is designed to do. Hence, this strategy a smart choice in the search for the best nail fungus treatment.
Whatever the nail fungus cause may be, consistency and strategy are your strongest allies for healthy nails.
For illustration purposes only.
