What Is the ICD-10 Code for Tinea Unguium (Nail Fungus)?

Toenail fungus is an infection caused by different types of fungi. The symptoms include thickened, crumbly, and discolored nails.

The most common causes of toenail fungal infections are warm and moist environments such as gym lockers and public showers (1), so make sure to keep your feet protected in such places.

Athlete's foot (tinea pedis) is a fungal infection that can occur if your feet sweat too much within tight-fitting shoes or if your shoes are damp. This can also spread and develop into toenail fungus. Timely intervention to treat toenail fungus will effectively help you get rid of it.

What Is the ICD-10 Code for Nail Fungus?

The International Classification of Diseases (ICD) assigns different codes for diseases, their causes, and signs or symptoms.

The Tenth Revision of the International Classification of Diseases, the ICD-10, is the standard transaction code set for diagnostic purposes under the HIPAA. The ICD codes have to be consistent between the condition and the treatment administered to claim insurance.

The ICD-10 code for fungal infection of the nails (tinea unguium) is B35.1 (2).

What Is Nail Fungus Also Known As?

Nail fungus is also known as onychomycosis. It is caused by fungi such as dermatophytes, yeasts, and saprophytic molds. There is, however, a distinction between nail fungus and nail mold. Surprisingly, nail mold is not caused by a "mold" or fungus but rather a type of bacteria.

When onychomycosis is caused by dermatophytes, it is called tinea unguium (3).

What Fungal Species Are Responsible for Nail Fungus?

The most common dermatophytes that causes nail fungus are:

• Trichophyton rubrum
• Trichophyton mentagrophytes

Around 85–90% of all cases of toenail fungus are caused by these dermatophytes (4). The other organisms include candida, a form of yeast. However, it is more common in fingernail infections.

How Is Nail Fungus Diagnosed?

Nail fungus has very specific signs that can be easily detected. The nails are whitish-yellow in color, brittle, and crumbly. They may have a slight smell, and you may experience pain. In some cases, the nail may get detached from the nail bed.

However, it is best to show a dermatologist or a podiatrist for the right diagnosis. They will examine the affected nail and ask you about your symptoms. They may also take a nail clipping and send it for a fungal culture.