• Which groups are particularly advised to have this test if nail changes occur?

In addition to those showing nail changes, individuals with diabetes or weakened immune systems should consider this test, as nail infections can be more serious for them.

• Are there any dietary requirements or fasting needed for the KOH nail test?

No, fasting is not required for this procedure.

Medical Laboratories

Rapid Nail Fungus Test

Fungal Detection by KOH Preparation (Nail)

Instant detection of nail fungi causing discoloration and thickening, helping establish an effective treatment plan to restore the healthy and natural appearance of your nails quickly.

Trusted medical contentUpdated: 04-09-2026Views: 81LHL-2447

About this service

Potassium Hydroxide (KOH) preparation for nails is a rapid microscopic test designed to detect fungi in nail clippings or infected tissue. Samples from the affected nail (from the thickened, crumbly, or discolored part) are taken, placed on a microscope slide with KOH solution (10-20%). The solution dissolves the hard keratin of the nail, making fungal filaments (hyphae) visible under the microscope if an infection is present.

Conditions and notices

Fasting is not required

Fasting is not required.

Proper sample collection: Clippings should be taken from the affected part of the nail (thickened, crumbly, discolored) as deep as possible near the nail bed, using a sterile nail clipper or scraper. The deeper the sample, the more accurate the result.

Avoid using topical antifungal medications (creams, varnishes) on the affected nail for at least two weeks before taking the sample.

For women: Remove all nail polish completely before taking the sample.

Frequently Asked Questions

Short answers to the FAQs published with this service.

• What symptoms suggest a need for a KOH nail test?

Symptoms include nails turning yellow, white, or brown, thickening and crumbling of the nail, or the nail plate separating from the nail bed.

• Can other conditions look like nail fungus?

Yes, conditions such as psoriasis, repeated physical trauma, or eczema can cause nail changes that resemble a fungal infection.

• What is the primary purpose of the KOH nail preparation test?

The test is used for the rapid and direct diagnosis of nail fungal infections, clinically known as onychomycosis.

• Why is it necessary to confirm a fungal infection before starting treatment?

Rapid Nail Fungus Test

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Conditions and notices

Frequently Asked Questions

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