What Is Toenail Fungus?

Toenail fungus (onychomycosis) is an infection of the nail and sometimes surrounding tissue. It is extremely common with 20% of the general population and 75% of people over 60 years old affected. Often, the problem is cosmetic, but many patients also experience pain. Sometimes toenail fungus can lead to more serious infections.


Most patients see yellowing and thickening of the nail. Sometimes the area around the nail itches. With time the nail may become brittle with jagged edges, deformed, or detached from the nail bed. Trimming your thickening nail can become difficult. If the nail gets too thick, wearing shoes can become uncomfortable.


Multiple fungi species can infect the nail. Fungus grows well in warm, moist environments such as showers. Fungus infection is one of the few foot problems that affect more men than women, perhaps because more men walk barefoot in locker rooms. Age is a factor, too. Half the sufferers are people older than 70. Other risk factors include diabetes, vascular insufficiency, or malnutrition.


To reduce your risk of developing toenail fungus, be sure to wear flip flops or sandals when you use a public locker room or shower. Use foot powders and change your socks frequently to keep your feet dry. 

Professional pedicures can transmit infections if not done properly. Make sure the salon you visit meets the following standards:

  • Maintains clean, sanitary conditions
  • Is licensed and displays the licenses—with photo ID—of each operator
  • Uses cleaned, sterilized or single-use implements for each customer
  • Uses small brushes to prevent nail polish and other products from coming in contact with the skin


Diagnosis is made based on clinical exam and occasionally will be confirmed by viewing scrapings of the nail under a microscope or growing the fungus in a culture medium. This is not an easy condition to cure, so rather than trying home treatment with over-the-counter medications, it's best to see your foot and ankle orthopaedic surgeon. As with many conditions, nail fungus infections are easier to treat if you catch them early.


Your surgeon may trim your nail and scale away the dead layers of the nail. You also may be prescribed a topical medication. If the infection is very far advanced, topical medication won't be able to penetrate the thickened nail. In some cases, you can take prescription oral medication. These are very effective but must be taken for several months and are used when there is risk of skin breakdown or infection.

Removal of the nail can reduce symptoms rapidly, but regrowth of the nail can take one year during which time local treatment for fungus can be used. Oral medications include terbinafine (Lamisil), itraconazole (Sporanox), and griseofulvin (Fulvicin). Treatment regimens vary and can last between six weeks and one year. Side effects of systemic treatment include gastrointestinal disorders, liver toxicity, skin rash, and other hypersensitivities. In addition, these medications should not be taken during pregnancy or if there is a chance you will become pregnant. 


Healing time depends on the type of treatment used. Prevention of a new infection is important. Foot and ankle orthopaedic surgeons recommend good foot hygiene, frequent changing of socks, and rotating pairs of shoes to allow your feet to completely dry between uses. Also, avoid going barefoot in locker rooms and around swimming pools. If you get pedicures, make sure the nail salon uses sterilized instruments.

Risks and Complications

More significant infection is uncommon, but in patients with a compromised immune system the thickened nail can be an entry site for bacterial infection that may become limb threatening. 


Last reviewed by David Porter, MD, 2018

The American Orthopaedic Foot & Ankle Society (AOFAS) offers information on this site as an educational service. The content of FootCareMD, including text, images, and graphics, is for informational purposes only. The content is not intended to substitute for professional medical advice, diagnoses or treatments. If you need medical advice, use the "Find a Surgeon" search to locate a foot and ankle orthopaedic surgeon in your area.