Causes, Symptoms and Complications of Toenail Fungus

Causes of toenail fungus

Toenail fungus, medically known as Onychomycosis (On-i-ko-mi-KO-sis), is one of the most frequently treated foot problems that accounts for more than half of the nail abnormalities. It is a fungal infection in one or more of your nails that is primarily caused by a group of fungi called Dermatophytes (der-mat-o-phtes). Yeasts and molds are other types of fungi that cause fungal infections. This slow growing infection usually occurs when microscopic fungi enter through a tiny cut or break in the nail. Dermatophytes live off the dead keratin between the top layers of the skin and nail. They thrive in warm, moist, dark environments.

It is difficult to determine exactly where how or where an infection is acquired, but it is spread through direct contact with a fungi or yeast spores and mold. This can happen when walking barefoot or wearing contaminated shoes or socks. It can also be spread from person to person. Toenail fungus is not caused by genetics or poor hygiene. Not all people are equally susceptible to getting toenail fungus.

Infections are more common with people over 60 because they tend to have poorer blood circulation to the toes and increased exposure to fungi due to age. Toenail fungus affects males more than females. Your risk of developing nail fungus increases if any of the following conditions are present: diabetes, weakened immune system, poor circulation, athlete’s foot and hyperhidrosis (hy-per-hi-drosis) — excessive perspiring. Your risk also increases if you work in a moist or humid environment, wear improper footwear with poor ventilation and moisture absorption, have trauma to the nail or another infection, or walk barefoot in public places or a household occupied by an infected person. It can also be contracted from sharing nail clippers, nail files, nail polish or towels.


The symptoms may vary depending on the type of fungus that is present; however, it is likely that toenail fungus is present if your nails have the following: changes in shape, discoloration, thickening, detachment, brittleness, build-up of white debris beneath the nail or foul odor. In advanced cases, the nail can turn brown or black. Your podiatrist will be able to confirm your condition by closely examining your toes; however, a scrapping may have to be examined under a microscope or cultured for lab confirmation.


Once the fungus is present, it will not go away by itself and the condition usually worsens over time. Toenail fungus can be present in one nail and spread to other nails. If you have athlete’s foot, the infection can be spread from your skin to your nails.

In advanced cases, toenail fungus can be painful, causing an irritation and burning sensation in the infected areas. Left untreated, this condition can cause permanent damage to the nail and lead to other serious infections.

Those at greatest risk are people with chronic diseases such as immune system deficiencies (leukemia, AIDS or organ transplant recipients), circulatory problems, diabetes mellitus and athlete’s foot.

Unfortunately, toenail fungus can also hamper a person’s quality of life. Some people can develop significant psychological problems from the poor appearance of their nails. Studies have shown that toenail fungus has a negative effect on their quality of life. In one study, 75 percent of the subjects were embarrassed by their nails. Women were embarrassed more than men (83 percent vs. 71 percent). Twelve percent of the subjects reported that their infection interfered with social relationships, and 15 percent avoided social situations all together.