Onychomycosis causes, symptoms and treatment

What is onychomycosis?

Onychomycosis (on-ih-koh-my-KOH-sis) is the medical term for a toenail or fingernail fungal infection. It is a common condition, affecting about 10% of the general population. It’s more common in older people, and about half of people over age 70 have it. As the fungus infects deeper, the nails can thicken, crumble, become discolored, and may separate from the nail bed. It can affect one or all nails. Severe nail fungus can be painful and cause permanent nail damage.

Fungal infection is more common on toenails because they grow slower and have less blood supply. Toenails are confined in dark, moist environments most of the time, which is ideal for fungi to grow and thrive. If it doesn’t bother you, no treatment is needed. If it progresses or becomes painful you may be prescribed antifungal medications. Even with successful treatment, it recurs in up to half of cases. Newer antifungal medications make treating it easier and more effective.

Why should I worry about onychomycosis?

Nail fungus infection can be more than just a cosmetic problem. It can be uncomfortable or painful, and lead to other infections, or foot ulcers in people with diabetes. If you have nail fungus, even a minor injury to your feet can lead to a more serious infection in your body, especially if you have diabetes, are older or have a weak immune system.

What causes onychomycosis?

Fungal nail infections are caused by various types of fungi. The most common fungus is dermatophyte, but yeasts and molds can also cause nail infections. Onychomycosis causes about a third of all fungal skin infections.

It’s more common in older people because their nails become brittle and dry as they grow older. This allows fungi to enter the cracks in the nails. Poorer blood circulation to the feet and a weakened immune system can also contribute to nail fungus. Nail fungus can also begin with athlete’s foot (tinea pedis) and spread to the nails. Athlete’s foot is a fungus that causes blisters, irritation and painful cracks in the skin and between the toes. Both athlete’s foot and nail fungus are easily spread to other people.

Who’s at risk for onychomycosis?

Onychomycosis is more likely to occur in people who:

Are over age 60
Have a history of nail injury
Have a history of athlete’s foot or other fungal infections
Have distorted or misshapen nails
Sweat excessively (hyperhidrosis)
Smoke
Have psoriasis, diabetes, or HIV (human immunodeficiency virus) infection
Have a weakened immune system or circulation problems
Wear enclosed footwear
Share bathing or swimming facilities, showers or gyms

What are the symptoms of onychomycosis?

Symptoms of nail fungus include nails that are:

Brittle, crumbly or ragged
Thickened
Whitish to yellow-brown discoloration
Distorted in shape
A dark color, caused by debris build-up under a nail
Unpleasant odor
Painful, in severe cases

Severe nail fungus can lead to other infections, especially if you have diabetes, take certain medications or have other conditions. Diabetes can cause reduced blood circulation, and compromise nerves in the feet. Diabetes also puts you at a greater risk of foot ulcers, and cellulitis, a very serious bacterial skin infection.

How is onychomycosis diagnosed?

It is diagnosed by examining the nails. Your doctor may take nail clippings or scrape some of the debris from under your nail and send it to a laboratory for analysis. A diagnosis is important because psoriasis can look like nail fungus. Yeast and bacteria can also cause nail infections. Identifying the exact fungi that’s causing the infection helps determine the best treatment for your needs.

What are the treatment options for onychomycosis?

You can try nonprescription antifungal nail creams and ointments. If these don’t help, or the infection comes back, see your doctor or dermatologist. Fungal nail infections can be difficult to treat and treatment can take months before you see improvement. Successful treatment gets rid of the fungi or organism that caused the infection, and restores the nail’s normal appearance. Even with treatment, from 10% to 50% of infections return, due to reinfection or failure to get rid of the fungi.

Treatment options include:

Antifungal medications taken internally, and/or applied to the nail and surrounding skin. Cure rates for internal antifungals range from 48% to 76%. They include Lamisil and Sporanox, which work by helping a new nail grow. The healthy nail slowly replaces the infected nail, over a period of four months or longer. The medications have to be taken for about three months. They are less successful in people over age 65. These drugs can cause side effects such as skin rash or liver damage. They are not recommended for people with liver disease, congestive heart failure or who are taking certain medications for other conditions. Topical therapies work slowly and are less successful. Oral antifungal medications work more quickly.
Debridement (removing dead tissue or debris from under and around the nail) increases cure rate when used before antifungal medications.
Antifungal nail polish is applied daily to the nail and surrounding skin. After a week, the seven layers of polish are removed with alcohol and the process starts over. This must be done for about a year.
Antifungal nail cream is applied to the nails after you soak them to soften the nail. It works better if the nails are first thinned. Your doctor can file down the nail’s surface. Or, you can apply a lotion that includes urea to soften the nail. This permits the medication to penetrate the hard nail and reach the fungus.
Surgery to remove the nail allows antifungal medication to be applied directly to the infected area. However, some infections are not affected by antifungal treatments. In these severe cases, the nail may have to be removed permanently to relieve pain.
Lasers and light therapies are being studied to determine if they can help cure infections.

Prevention is an important part of treatment because it can increase cure rates and prevent reinfection. It’s important to:

Keep hands and feet clean. Wash hands after touching infected nails or skin with athlete’s foot infection. After bathing, moisturize nails to keep them soft so they don’t crack.
Trim toenails straight across and file down thickened areas. Always disinfect nail clippers after each use.
Wear sweat-absorbing or wicking socks, or change socks several times a day.
Wear shoes made of natural materials that breathe. Get rid of old shoes or treat them with antifungal powder.
Always wear footwear in shower rooms, pool areas, gyms and locker rooms
Don’t wear nail polish or artificial nails.
Be certain your nail salon sterilizes all manicure tools after each customer.

Mayo Clinic. (July 2020). Nail Fungus. Retrieved 9-25-21, {https://www.mayoclinic.org/diseases-conditions/nail-fungus/symptoms-causes/syc-20353294}

Mayo Clinic. (July 2020). Nail Fungus Diagnosis and Treatment. Retrieved 9-25-21, {https://www.mayoclinic.org/diseases-conditions/nail-fungus/diagnosis-treatment/drc-20353300}

Westerberg, D.P., Voyack, M.J. (Dec. 2013). Onychomycosis: Current Trends in DIagnosis and Treatment. (American Family Physician) Retrieved 9-25-21, {https://www.aafp.org/afp/2013/1201/p762.html}

Medically reviewed by:

Dr. Javeed Siddiqui, MD, MPH

Dr. Siddiqui is the Chief Medical Officer at TeleMed2U responsible for clinical and technical program development as well as maintaining a thriving telemedicine practice in infectious diseases which includes specialized care of Hepatitis and HIV.

‍Meet our doctors

Onychomycosis