Toenail Fungus

(Toenail Fungus or Onychomycosis)

Edited by Judith Smith, MD


Clinical Presentation

Toenail fungus (onychomycosis) is a common, often asymptomatic abnormality affecting toe nails. Patients complain of unsightly looking toenails but rarely have significant symptoms. Trauma to the nail bed can also cause nail deformity and is part of the differential diagnosis. Toenail fungal infections are characterized by any of the following symptoms: yellow streaks or discoloration of the nail bed, discolored and thickened toenails, brittle and thickened nails, soft and powdery nail surfaces, white spots or streaks on the nail surface, build ups of pieces of skin and nail fragment under the nail bed and damaged brown or grey nail surfaces. The condition is caused by fungus (dermatophyte), a common fungi tricophyton, microsporum, epidermophyton, or yeast candida albicans. The condition is more common in patients with diabetes and in some instances may lead to increasing morbidities in these patients. Diagnosis is made by clinical examination, or by microscopic evidence of fungal elements from scrapings.


Eradicating a fungal infection has proven difficult because the infection is embedded deep within the nail and is difficult to reach. Treatment may focus on controlling the condition or eradicating it. Traditional treatment options have included:

Local treatments such as nail lacquer

For mild to moderate toenail fungus, a topical anti-fungal can be of benefit. The lacquer is applied daily to the affected nail. Improvement in the nail is often achieved after an extended period of time (1 year). The issue with this approach is that the lacquer often poorly penetrates the nail plate. As a result, this treatment may be very effective in terms of controlling the condition and producing improved nails, however, it only eradicates the infection in less than 10 percent of patients.

Oral medication, such as terbinafine or itraconazole

Oral anti-fungals (itraconazole and terbinafine) can be taken once daily by mouth for a variable period of time, usually 12 weeks, with reasonable success of eradicating the fungal infection (on the order 60-70 percent success). The problem with this treatment in addition to cost is the potential for serious liver problems. These medications are metabolized in the liver and have been associated with elevated liver enzymes and liver failure, potentially leading to the need for liver transplant or death. As a result of this, in July 2001 the FDA consumer updates outlined a health advisory delineating the serious risks of these medications. However, for patients who otherwise have a healthy liver, these medications are likely to be well tolerated provided the effects are closely monitored by a physician.

Laser therapy

Laser therapy is becoming increasingly popular for the treatment of fungal infections. There are different types of lasers and each requires a different treatment protocol. There is a general lack of peer-reviewed data on laser treatment. However, there are retrospective studies that suggest that they may be of some benefit. The laser is thought to work by penetrating the nail and killing the fungi.



Edited July 24, 2017