Fungal Toenails

Nail fungus is an infection under the hard keratin tissue that slowly damages your nails. The medical term is onychomycosis, and this infection is caused by microscopic fungi that thrive in warm, damp environments, especially those without much air circulation. 

As the pathogen gets under your nails through small cuts or separations between the nail bed and the hard tissue, it multiplies and spreads rapidly. It begins to break down your toenails, causing thickening, brittleness, discoloration, and cracking. Sometimes the affected toe emits a foul odor and debris collects under the hard tissue. The changes in nail shape can make it uncomfortable to wear shoes.

Nail fungus doesn’t improve without treatment. In fact, it typically gets worse and causes complications if allowed to fester. Nail damage opens your toes to bacterial infections as well, which is a particularly serious risk for people with diabetes or other conditions that impair the immune system.

The fungi do not need a wide opening to cause an infection. Cracks in the nails or skin, or a small gap between the nail and nail bed, are more than sufficient.

You may have been exposed to fungus in the environment, and then—if your toes are sweaty and warm—the infection takes hold. Public pools, locker rooms, saunas, gyms, and bathrooms are all prime breeding grounds for fungus.

The infection is contagious, so it can easily pass from one toe to another, to the floors and footwear around you, and even to other people. Walking barefoot in high-risk areas, sharing footwear with an infected person, or touching the feet of someone with the fungus all sharply increase your chances of developing the condition. 

The same kinds of fungi that cause athlete’s foot also cause fungal toenails. If you have a history of athlete’s foot, the fungus may have transferred from your skin to your nails via your shoes and socks.