How is a fungal fingernail infection diagnosed and treated?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Fungal nail infections (onychomycosis) are diagnosed through a close visual examination of the nail combined with laboratory tests on nail scrapings or clippings to confirm the presence of fungus. Treatment typically involves topical antifungal creams, lacquers, or oral antifungal medications, depending on the severity and extent of the infection.

Because fungal nail infections can look similar to other nail conditions—like psoriasis, bacterial infections, or trauma—getting the right diagnosis matters. Guessing wrong can mean months of ineffective treatment. A free, instant, online symptom check can help you understand what may be causing your nail changes and guide your next steps, whether that's home care or seeing a doctor. It takes only a few minutes and could save you time, money, and unnecessary worry.

Reviewed for medical accuracy: 07/15/2026

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Explanation

Doctors start by checking your nail and asking about any problems you have noticed. They might gently scrape a bit of the nail or the skin around it to send to a lab. In the lab, experts use tests like a KOH exam or even grow the fungus in a culture to see if it is present.

New tools like special cameras or even computer programs can help check for fungus too. If you're experiencing nail changes and want to understand your symptoms better before seeing a doctor, you can use a free AI symptom checker to get personalized insights. When it comes to treatment, many fungal nail infections are treated with antifungal medicines. Sometimes the medicine is put directly on the nail as a cream or lacquer, but if the infection is more severe or widespread, doctors may prescribe pills that you take by mouth. The treatment can take a long time because nails grow slowly.

Keeping your nails dry and trimmed and following your doctor's advice will help treat the infection.

(References)

Elewski BE. Onychomycosis: pathogenesis, diagnosis, and management. Clin Microbiol Rev. 1998 Jul;11(3):415-29. doi: 10.1128/CMR.11.3.415. PMID: 9665975; PMCID: PMC88888.
Lim SS, Ohn J, Mun JH. Diagnosis of Onychomycosis: From Conventional Techniques and Dermoscopy to Artificial Intelligence. Front Med (Lausanne). 2021 Apr 15;8:637216. doi: 10.3389/fmed.2021.637216. PMID: 33937282; PMCID: PMC8081953.
Falotico JM, Lipner SR. Updated Perspectives on the Diagnosis and Management of Onychomycosis. Clin Cosmet Investig Dermatol. 2022 Sep 15;15:1933-1957. doi: 10.2147/CCID.S362635. PMID: 36133401; PMCID: PMC9484770.

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