Onychomycosis: Symptoms, Photos, AI Analysis 🚨 ICD-10: B35 | ICD-11: 1F2Z

Onychomycosis is a fungal infection of the nails that causes changes in their color, structure, and appearance. It most commonly affects toenails and less frequently fingernails.

The disease is caused by different types of fungi that can penetrate the nail plate and gradually destroy it. Onychomycosis does not always cause pain, but over time it can lead to noticeable nail deformity.

The infection can be transmitted through contact with contaminated surfaces (e.g., in swimming pools, gyms) or by sharing personal items. It is a common condition that is usually treatable but requires time and patience.

What to do if you suspect it

If you notice changes in nail color, thickening, or destruction, it is important not to delay diagnosis.

The first step is to see a dermatologist or dermato-venereologist. The specialist will examine the nails and, if necessary, order additional tests to confirm the fungal nature of the disease.

Additionally:

• do not cover changes with nail polish before diagnosis
• do not use antifungal medications on your own without confirmed diagnosis
• check whether there are changes in the skin of the feet or between the toes

Timely medical evaluation is important because different types of fungi require different treatment approaches. Without proper diagnosis, therapy may be ineffective.

How it looks

The appearance of onychomycosis can vary greatly depending on the form and stage.

Most commonly observed:

• change in nail color — yellow, white, gray, or dull appearance
• thickening of the nail plate
• irregular surface, ridges, or crumbling
• nail separation from the nail bed

Sometimes the infection starts at the edge of the nail and gradually spreads toward the base. In other cases, changes begin at the nail base or appear as white spots on the surface.

Over time, the nail may deform and partially break down. Manifestations vary from subtle to severe.

Below in the article you can view real photos to better understand how the condition looks.

Main symptoms

The main signs are changes in nail appearance:

• discoloration (yellowing, whitening, dullness)
• thickening or thinning of the nail
• brittleness and crumbling
• nail detachment

The disease usually develops slowly and may remain painless for a long time. Pain or discomfort may appear with advanced changes or pressure from footwear.

Causes

Onychomycosis develops due to infection with fungi that break down keratin — the main structural protein of the nail.

Infection may occur through:

• contact with contaminated surfaces (floors, mats, shoes)
• shared personal items (nail scissors, towels)
• close contact with an infected person

Risk factors include:

• increased moisture and foot sweating
• tight or poorly ventilated footwear
• minor nail injuries
• weakened immune system
• chronic diseases (e.g., diabetes)

How it develops

Fungi enter the nail or under it and gradually multiply. They destroy keratin, which makes the nail strong.

As a result, the nail plate loses its structure, becomes brittle, changes color, and deforms.

The infection may spread from the edge of the nail toward the base or vice versa. In some cases, only the surface is affected.

Without treatment, the process usually progresses slowly but may involve more nails over time.

Forms and types

There are several types of onychomycosis.

By location:

• infection starting from the nail edge and spreading
• changes starting at the nail base
• white or yellow spots on the nail surface

By structural changes:

• mild form — only color changes
• thickened form — nail becomes dense and irregular
• thinned form — nail becomes fragile and may detach

These differences are important for choosing treatment.

When to see a doctor

Seek medical attention if:

• nail color or structure changes
• the nail thickens, crumbles, or detaches
• the infection spreads to other nails
• there is pain or discomfort
• symptoms persist for a long time

Also consult a doctor if previous treatment has failed.

Treatment

Treatment of onychomycosis aims to eliminate the fungus and restore healthy nail growth.

Depending on the case:

• topical treatments (lacquers, creams, solutions) — for limited infection
• systemic antifungal drugs — for more extensive cases

Additionally:

• regular nail care
• keeping feet dry
• avoiding reinfection risks

Treatment takes time because nails grow slowly. Even after the infection is cleared, it takes months for a healthy nail to grow back.

Therapy is always individually prescribed by a doctor.

Q&A

Can nail fungus be cured?

Yes, in most cases it can be treated successfully, but it may take several months due to slow nail growth.

Are tablets always required?

No. Mild cases may be treated with topical medications only, but more severe cases may require oral drugs.

Is onychomycosis contagious?

Yes, it can spread through surfaces and shared items, so hygiene is important.

Can you use nail polish?

Before diagnosis, it is better to avoid it because it can hide symptoms and interfere with evaluation.

Why does treatment take so long?

Because nails grow slowly and need time to fully replace the infected portion.

Can it spread to the skin?

Yes, it may spread to the feet or between toes.

Is it dangerous?

Usually not, but without treatment it can progress and significantly damage nails.

Can you get infected in a swimming pool?

Yes, humid public places are a common source of infection.

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Medical sources

• World Health Organization (WHO) — Fungal infections epidemiology
• Fitzpatrick’s Dermatology, 9th Edition
• European Academy of Dermatology and Venereology (EADV) Guidelines
• American Academy of Dermatology (AAD) — Nail fungus
• Bolognia Dermatology

Images of nail fungus: