Nail fungus is a common condition that begins as a white or yellow spot under the tip of your fingernail or toenail. As the fungal infection continues, it may cause your nail to discolor, thicken, and crumble at the edge…and can affect several nails.
If your condition is mild, you may not need treatment. If it’s painful and has caused thickened nails, self-care steps and medications may help. But even if treatment is successful, nail fungus often does comes back.
When fungus infects the areas between your toes and the skin of your feet, it's called athlete's foot.
SymptomsYou may have nail fungus if you have one of the following:
- Whitish to yellow-brown discoloration
- Brittle, crumbly or ragged
- Distorted in shape
- A dark color, caused by debris building up under your nail
- Smelling slightly foul
When to see a doctor
You may want to see a doctor if self-care steps haven't helped and the nail becomes increasingly discolored, thickened or deformed. If you have diabetes and think you're developing nail fungus, you should see a doctor.
Fungal nail infections are caused by various fungal organisms. The most common cause is a type of fungus called dermatophyte. Yeast and molds also can cause nail infections.
Fungal nail infection can develop in people at any age, but it's more common in older adults. As the nail ages, it can become brittle and dry. The resulting cracks in the nails allow fungi to enter. Other factors such as reduced blood circulation to the feet and a weakened immune system may also play a role.
Toenail fungal infection can start from athlete's foot (foot fungus), and it can spread from one nail to another. But it is uncommon to get an infection from someone else.
Risk factorsFactors that can increase your risk of developing nail fungus include:
- Being older with reduced blood flow, more years of exposure to fungi and slower growing nails
- Sweating heavily
- Having a history of athlete's foot
- Walking barefoot in damp communal areas like swimming pools and shower rooms
- Having a minor skin or nail injury or a skin condition, such as psoriasis
- Having diabetes, circulation problems or a weakened immune system