Toenail Fungus and Psoriasis: A Dermatologist’s Guide to Telling Them Apart
Share
Your toenails are thick, yellowing, and brittle. For most people, the immediate assumption is toenail fungus. But if you are one of the millions of Americans living with psoriasis, the answer may not be so simple. Welcome to one of dermatology's great mimics: the strikingly similar appearance of nail psoriasis and a fungal infection (onychomycosis).
This visual overlap can lead to significant confusion, frustration, and months or even years of using the wrong treatments with no results. Understanding the fundamental differences—and the surprising connection—between these two distinct conditions is the first and most critical step toward getting the right help.
This guide, based on the latest clinical information, will clarify the link between psoriasis and toenail fungus, provide a side-by-side comparison of the key symptoms, and explain why a definitive diagnosis from a dermatologist is the only path forward to achieving clearer, healthier nails.
Understanding the Two Conditions at Their Core
Before we can compare symptoms, it’s essential to understand that nail psoriasis and toenail fungus are two fundamentally different conditions. One is an internal autoimmune response, and the other is an external infection. This core difference is why their treatments are not interchangeable.
What is Nail Psoriasis?
Nail psoriasis is not an infection. It is a chronic autoimmune condition that occurs in people who have psoriasis. According to the National Psoriasis Foundation, psoriasis is a disease where the body's immune system goes into overdrive, causing skin cells to grow too quickly. When this process affects the nails, it disrupts their normal growth cycle, leading to symptoms like pitting, discoloration, and separation from the nail bed.
What is Toenail Fungus (Onychomycosis)?
Toenail fungus, clinically known as onychomycosis, is an infection. It is caused by an external pathogen—a microscopic fungus, usually from a group called dermatophytes—that invades the nail, the nail bed, or the surrounding skin. As the American Academy of Dermatology (AAD) explains, these fungi thrive in warm, damp environments. Because it is caused by an external organism, toenail fungus is contagious and can be contracted from contaminated surfaces.
The Connection: Does Psoriasis Increase Your Risk of Fungus?
The short answer is a definitive yes. While psoriasis does not cause a fungal infection, it can make you significantly more vulnerable to developing one.
Think of a healthy nail as a sealed, protective barrier. Psoriatic nail disease damages this barrier. It can cause the nail to lift from the nail bed (onycholysis) and create a buildup of chalky debris, effectively leaving the door wide open for opportunistic fungi to invade.
For this reason, clinical studies have consistently shown that the prevalence of onychomycosis is significantly higher in people with psoriasis. This increased vulnerability makes proactive hygiene critical, as preventing toenail fungus recurrence can be especially challenging when the nail is already compromised.
Symptom Smackdown: Nail Psoriasis vs. Toenail Fungus
While a definitive diagnosis must come from a dermatologist, understanding the classic signs of each condition can help you have a more informed conversation.
|
Symptom / Feature |
Nail Psoriasis (Autoimmune Response) |
Toenail Fungus (Infection) |
|
Pitting |
A hallmark sign. Small, ice-pick-like depressions on the nail surface. |
Rare. The nail surface is more likely to be rough, flaky, or uneven. |
|
Discoloration |
Often presents as a yellowish-pink "salmon patch" or "oil drop" spot under the nail. |
Typically a white, yellow, or brown discoloration that often starts at the tip of the nail. |
|
Nail Lifting (Onycholysis) |
Common. The nail separates from the nail bed, often with a distinct yellowish border. |
Common. The separation is often accompanied by crumbly, chalky debris underneath. |
|
Debris Under Nail (Hyperkeratosis) |
Common. The debris is typically dry, chalky, and silvery-white. |
A hallmark sign. The debris is often softer, more powdery or pasty, and may have a slight odor. |
|
Nail Crumbling |
The entire nail structure feels weak and compromised. |
The crumbling is often concentrated at the edges and tip of the nail. |
|
Associated Symptoms |
Often occurs alongside psoriasis symptoms on the skin or psoriatic arthritis. |
May occur alongside Athlete's foot (peeling, itchy skin). |
The Diagnostic Dilemma: Can You Have Both?
To make matters even more complicated, the answer is yes. It is relatively common for a person with psoriatic nails to develop a secondary fungal infection in the same nail.
This is because the damage from psoriasis creates the ideal entry point for fungi. When this happens, you are dealing with two separate problems simultaneously, which makes an accurate diagnosis essential.
Getting It Right: Why a Dermatologist's Diagnosis is Essential
Given the visual similarities, self-diagnosing is a recipe for failure. A board-certified dermatologist is trained to use specific tools to arrive at a definitive diagnosis.
Here’s what you can expect:
-
Visual Examination: An experienced dermatologist can often spot tell-tale clues, like the classic pitting or "oil drop" signs of psoriasis.
-
Nail Scraping or Clipping (KOH Test & Fungal Culture): This is the gold standard for confirming a fungal infection. According to the American Academy of Dermatology, this sample can be examined under a microscope (a KOH test) or sent to a lab for a culture to grow and identify the specific type of fungus. This same method can be used to differentiate between toenail fungus vs. Athlete's foot by testing the skin.
-
Nail Biopsy: In complex cases, a doctor may perform a nail biopsy to definitively identify signs of psoriasis.
Two Conditions, Two Very Different Treatment Plans
Receiving the correct diagnosis is critical because the treatments are completely different.
Treating Nail Psoriasis
The goal is to manage the underlying autoimmune response. This is done with medications that regulate the immune system, such as:
-
Topical steroids or vitamin D analogues.
-
Injections of corticosteroids into the nail matrix.
-
Systemic medications, including biologic drugs, for severe cases.
Treating Toenail Fungus
The goal is to address the invading fungal organism. This requires antifungal medication.
One option is a prescription compounded formulation like Clarivia. Clarivia is a compounded topical formulation prescribed by a licensed U.S. physician after an online evaluation. It combines two prescription antifungal agents—Itraconazole and Terbinafine—with DMSO, a solvent used to facilitate dispersion. These are ingredients commonly used in the treatment of toenail fungal conditions. Because it is applied topically, this approach minimizes systemic exposure.
Important Information: Compounded products, such as Clarivia, have not been reviewed or approved by the FDA for safety or efficacy and are generally prescribed to accommodate personalized dosing requirements or allergies.
Treating Both Conditions Together
If your dermatologist confirms you have both psoriasis and a secondary fungal infection, they will create a combination treatment plan. This often involves using a prescription antifungal (like Clarivia) to address the infection, while simultaneously managing the autoimmune condition with psoriasis-specific therapies.
Frequently Asked Questions
Q: My dermatologist prescribed a biologic for my psoriasis. Will it help my nails?
A: Yes, systemic treatments like biologic drugs are often very helpful for nail psoriasis because they treat the underlying autoimmune condition. However, because these medications modify the immune system, it is important to monitor for secondary infections, including fungus, as discussed with your doctor.
Q: Can I use an over-the-counter antifungal if I suspect fungus but also have psoriasis?
A: It's best to get a definitive diagnosis first. If your nail condition is purely psoriasis, an antifungal product will have no effect. A recommended approach is to let a dermatologist identify the exact cause(s) before you begin any treatment.
Q: Can getting a pedicure make my nail psoriasis worse?
A: It potentially can. For people with psoriasis, any trauma to the skin or nails can trigger a flare-up (the Koebner response). Aggressive cuticle work can cause this. Furthermore, if the salon's tools are not properly sterilized, you risk introducing a fungal infection, making good nail salon safety practices critical.
From Confusion to Clarity: Your Path to Healthier Nails
The visual overlap between nail psoriasis and toenail fungus is one of the most challenging dilemmas in nail health. These conditions may look like twins, but they are fundamentally different.
The single most important takeaway is to stop guessing and seek professional clarity. A definitive diagnosis from a board-certified dermatologist is the only way to ensure you're on the right path.
Once you and your doctor have a clear diagnosis and strategy, you can move forward with confidence. If a fungal component is identified, you can learn more about physician-prescribed solutions like Clarivia.
References
(Medically reviewed and updated on October 6, 2025)