What is onychomycosis?

Definition

Onychomycosis is a nail infection caused by a fungus. The infection occurs more often on toenails than on fingernails.

Causes

The fungi that cause onychomycosis thrive in warm, moist
environments. Factors that may contribute to onychomycosis include injury to the
nail; exposure to warm, moist environments, such as locker rooms; damp socks;
tight-fitting shoes; and poor nail care.

Risk Factors

Risk factors for onychomycosis include smoking; type 1 or type 2 diabetes;
circulatory disorders, such as peripheral vascular disease; and immune system
disorders, such as human immunodeficiency virus (HIV)
infection. Persons who are sixty years of age or older are at higher risk.

Symptoms

Onychomycosis can affect one or more nails. Symptoms include a thickened nail that is difficult to cut, a brittle or ragged nail, a discolored or unsightly nail, and pain of a finger or toe with ordinary activities.

Screening and Diagnosis

A doctor will ask about symptoms and medical history and will perform a physical exam before possibly referring the patient to a specialist in skin and nail disorders (a dermatologist). The doctor may scrape or clip the nail to send a sample for testing. Tests on the nail sample may include a culture and a microscopic examination.

Treatment and Therapy

Because nails grow slowly, getting a completely clear nail can take up to one year. Onychomycosis can be difficult to treat and may return after treatment. Treatment options include prescription antifungal medications taken by mouth, creams and ointments, and antifungal nail lacquer. Surgery to remove the nail is sometimes performed in severe cases of onychomycosis. A new nail grows in its place.

Prevention and Outcomes

To help reduce the chance of getting onychomycosis, one should keep feet clean
and dry them after washing; keep hands dry and wear rubber gloves when cleaning;
keep nails short and clean and trimmed straight across; avoid trimming or picking
at the skin near nails; take care to avoid injuring toenails; avoid shoes that are
too tight; wear absorbent cotton socks and change them if they become damp; avoid
walking barefoot around swimming pools, locker rooms, and other public places;
choose a reputable salon for manicures and pedicures; avoid artificial nails,
which can trap moisture; and stop smoking. For persons with diabetes, the doctor
should be consulted about how to better control blood sugar levels.

Bibliography

Haggerty, M. “Don’t Let Fungal Nail Infections Get the Upper Hand.” Dermatology Insights (Spring, 2001). Available at http://www.aad.org/public/conditions/_doc/dispring01.pdf.

Nandedkar-Thomas, M. A., and R. K. Scher. “An Update on Disorders of the Nails.” Journal of the American Academy of Dermatology 52 (2005): 877-887.

National Library of Medicine. “Fungal Nail Infection.” Available at http://www.nlm.nih.gov/medlineplus/ency/article/001330.htm.

Rodgers, P., and M. Bassler. “Treating Onychomycosis.” American Family Physician 63 (2001): 663-672, 677-678.

Weedon, David. Skin Pathology. 3d ed. New York: Churchill Livingstone/Elsevier, 2010.

Wolff, Klaus, and Richard Allen Johnson. Fitzpatrick’s Color Atlas and Synopsis of Clinical Dermatology. 6th ed. New York: McGraw-Hill Medical, 2009.