A fungal skin infection occurs when a fungus (such as yeast or mold) grows and creates a reaction on your skin surface.
Fungi (the plural of “fungus”) spread by releasing particles called spores into the air and their surroundings. They’re more likely to infect areas of your skin that encounter high amounts of friction or moisture. A weakened immune system — such as from HIV/AIDS, cancer or its treatments, or immunosuppressant drugs — can also make a fungal infection more likely.
Here’s what you should know about the most common types of fungal skin infections, including what to do if you experience any signs or symptoms.
Healthy skin contains many different types of fungi that usually don’t cause infections. But when certain fungi grow out of control, the following problems can occur.
Ringworm (Tinea Corporis)
This type of fungal infection can occur anywhere on your body but is more common in skin folds. It’s distinguished by a circular rash with a reddish outline, which is where the “ring” in its name comes from. But despite the name, there is no worm involved.
Ringworm is caused by a group of fungi called dermatophytes, which thrive on skin, hair, and nail cells. This group of fungi can also cause athlete’s foot, jock itch, and nail fungal infections.
Athlete’s Foot (Tinea Pedis)
This type of infection usually begins between your toes, causing an itchy and scaly rash that can spread to the bottom and sides of your foot. It’s more common in people who develop sweaty feet while wearing tight-fitting shoes.
Athlete’s foot can affect one or both feet and can also cause blisters.
If it spreads, “athlete's foot can infect the toenails, and it can also spread to the groin, causing jock itch,” says Faranak Kamangar, MD, a dermatologist at Palo Alto Foundation Medical Group in Palo Alto, California.
Jock Itch (Tinea Cruris)
This type of fungal infection affects your groin and inner thighs. It mostly affects boys and men, and can be harder to cure than other types of fungal skin infections.
The risk for jock itch is greater with friction and prolonged moisture in the groin area, such as from sweating. If you have athlete’s foot, pulling up a waistband that touches your feet can lead to jock itch.
Yeast Infections (Cutaneous Candidiasis) of the Skin
A yeast (candida) infection of the skin can affect any area of the body, but most often affects warm, moist areas like the groin and armpits. It typically causes a reddish, growing skin rash.
“Yeast, particularly candida, love to inhabit areas of skin folds such as under the breasts or belly folds,” says Jordan Praytor, an instructor in the department of dermatology at Oregon Health & Science University in Portland.
Skin yeast infections are the most common cause of diaper rash in infants, and they also often affect people with diabetes or obesity.
Nail Fungus (Onychomycosis)
Different types of fungal infections can affect your toenails or fingernails, potentially causing them to become discolored and cracked. A toenail fungal infection is commonly seen in athlete’s foot.
Symptoms of fungal skin infections can vary depending on the type of fungus, your immune system’s response, and other factors.
Possible symptoms include:
Red, swollen, or bumpy skin
Itchy or scaly skin
Scaly, cracked, or peeling skin
Ring-shaped rash or red spots
Even the same type of fungus may cause different symptoms in different areas of your body. For example, the fungus that causes ringworm may cause an itchy or burning rash on your feet, classic ringlike patches on your inner thighs, or thickening and yellowing of your fingernails or toenails.
It’s important to recognize a skin fungal infection as soon as possible, since it may be easier to treat in its earlier stages. That’s particularly true for athlete’s foot, which often spreads to affect your toenails if left untreated.
As mentioned above, fungal skin infections are caused by yeast, molds, and other types of fungi.
Fungal infections are often spread in public spaces that may be damp and humid, like showers or locker rooms.
When your skin comes into direct contact with the fungus, you can develop a reaction. For example, if you borrow clothing or shoes from someone with a fungal infection, the fungus may spread to your skin.
And some dermatophyte infections (like ringworm) can be spread by direct contact with an infected person or animal.
A weakened immune system and poor nutrition may put you at greater risk for fungal infections.
To diagnose a fungal skin infection, your doctor will first take a look at the affected area. If it isn’t clear what type of infection you have, your doctor may take a tissue sample to help identify it.
Tissue samples may include:
Skin Scraping Your doctor may use a small tool to painlessly scrape off some skin cells for viewing under a microscope.
Nail or Hair Biopsy For a scalp or nail infection, your doctor may take a hair or nail clipping to view under a microscope.
Skin Biopsy and Culture Your doctor may take a small sample of skin so that the fungus can be grown and identified in a lab.
Contact your doctor if you’re not sure you have a skin fungal infection or another condition, or if your infection doesn’t respond to over-the-counter treatments.
“If over-the-counter treatments are not working after a few weeks of use, it is a good idea to obtain an evaluation for diagnosis and treatment,” says Dr. Kamangar.
Also contact your doctor if any of the following occurs:
Your rash spreads to other areas of your body.
Redness in the area of your infection gets worse.
Fluid is leaking from your rash.
You have a fever of 100.4 degrees F (38 degrees C) or higher.
Sometimes, a skin fungal infection will go away on its own. But in most cases, you’ll need to use an antifungal medicine in some form.
Medication Options
For simple cases of common infections like athlete’s foot or ringworm, you can use an over-the-counter topical treatment (cream or ointment). Active ingredients of these treatments include:
Clotrimazole
Ketoconazole
Miconazole
Terbinafine
If you have a widespread or more disruptive skin fungal infection, or if your infection doesn’t respond well to over-the-counter treatments, your doctor may prescribe a topical or oral prescription medication.
Active ingredients in prescription topical antifungal medications include:
Ciclopirox
Clotrimazole
Econazole
Active ingredients in oral antifungal medications include:
Fluconazole
Griseofulvin
Itraconazole
Terbinafine
There are certain cases when a doctor might prescribe an oral antifungal as a first-line treatment, such as when your toenails or fingernails are widely affected.
“Due to the thickness of the nails when infected, topical medication does a poor job of penetrating through the nail, and oral antifungals are often necessary,” says Praytor.
Self-Care and Hygiene
Self-care is an important aspect of treating any fungal skin infection. That typically means keeping the area clean and dry, and sometimes taking other measures to improve ventilation and hygiene in the area.
For athlete’s foot, you should:
Change your socks at least once a day.
Wear shoes with good ventilation.
Alternate pairs of shoes day to day.
Wear sandals or shoes at all times in public locker rooms, showers, or pool areas.
Tea tree oil is a home remedy for fungal skin infections that may be a useful addition to conventional treatments due to its antimicrobial properties. But different formulations containing tea tree oil may be more effective than others, and more research is needed on specific products that work best.
There are many different steps you can take to help prevent fungal skin infections:
Shower after sweating or getting dirty.
Don’t go barefoot in public areas.
Don’t share exercise equipment or towels.
Wear clean, dry, loose-fitting underwear.
Change your socks often.
Wear shoes with good ventilation.
Let your feet air out when possible.
Apply a medicated powder if you’re prone to athlete’s foot.
Don’t share shoes, unwashed bedding, or bath towels with family members.
Check any pets for ringworm, and see a veterinarian for treatment. (People can get ringworm from animals.)
Poor nutrition may increase your risk for some fungal skin infections, so make sure to follow a healthy diet with all the nutrients you need.
While fungal skin infections usually aren’t dangerous, they can be persistent. With treatment, they may clear up in a few days, though it may take a few weeks or longer.
Scalp ringworm and fungal nail infections can be the toughest to clear up, requiring consistent treatment for weeks or months.
Fungal skin infections rarely cause serious complications, but they can lead to distress and discomfort.
Sometimes, a fungal skin infection can lead to a secondary bacterial infection. This is one reason to see a doctor if your infection gets worse. For a bacterial infection, you may need treatment with antibiotics.
It’s possible to get an allergic reaction (known as a dermatophytid reaction) to a fungal skin infection on a completely different area of your body. This reaction tends to be itchy, with red bumps or patches. It doesn’t mean your fungal infection has spread to this area.
Fungal skin infections can cause an itchy, red, cracked, or peeling rash or patch nearly anywhere on your body.
Common types of fungal skin infections include ringworm, athlete’s foot, and yeast (candida) infections.
Over-the-counter topical treatments work well for many fungal skin infections, but more serious or persistent cases may require prescription medication.
You can help prevent fungal skin infections through hygiene and self-care measures like showering after activity and keeping problem areas clean and well ventilated.