Fungal Infections

These things are normal, normal. [Fungal infections] happen to nearly everybody at some point in their life.

—says Dr. Caren Campbell, a board-certified dermatologist in San Francisco, CA.

Sometimes, a fungal infection can feel like it came out of nowhere. And it might have. The skin is constantly changing, and it’s made up of thousands of microorganisms that try to live together in harmony, but sometimes that balance gets out of whack. Infections happen. They’re usually itchy.

But fungal infections can be tricky to identify because of how similar they appear to many other skin conditions, like eczema. A dermatologist is trained to identify them. So if you’re unsure if a rash is an infection, an allergic reaction, or a witch’s curse, visit a doctor for a proper diagnosis.

Fungal infections are sometimes referred to as mycoses.¹

There are millions of species of fungi all over the planet. But slicing mushrooms for dinner won’t lead to a fungal skin infection. The fungus responsible for most fungal skin infections exists naturally on the human skin at all times. “The malassezia yeast lives on everybody’s skin,” says Dr. Caren Campbell. “And it likes to overgrow in oil-rich environments. That includes sides of the nose, in between the eyebrows, on the scalp, behind the ears, and on the central chest of men.” Those are some, but not all, possible areas of fungal infection.

Yeast is a fungus that helps to foster skin health. To put it briefly—because the skin microbiome is a complex topic that’s still being studied—the amount of yeast on the skin is balanced out with “good” bacteria; they co-exist so that neither one becomes too abundant.²

But when this equilibrium is thrown off-balance, it can lead to an infection. Too much bacteria and oil can lead to acne. But too much fungi could lead to a variety of different infections in multiple locations on the body—usually places that get dark and moist, though, because that’s where fungi thrive. Common types of fungal infections include dandruff (seborrheic dermatitis), fungal acne (pityrosporum folliculitis), tinea versicolor, jock itch (tinea cruris), ringworm, yeast infections, and athlete's foot (tinea pedis).

The important thing to remember about fungal infections is that they’re rarely life-threatening and they’re often easily treated with over-the-counter antifungal creams.

Fungal Infections vs. Bacterial Infections

Bacteria and fungi live on the human body to provide a number of benefits necessary for healthy living, even though you can’t see them. But fungi are more complex organisms than bacteria.
Fungi are eukaryotes, which means they’re composed of cells that have a nucleus. Bacteria are prokaryotes, so they’re single-celled and have no nucleus. What this means for humans is that bacteria are much more adaptive and sly, and they’ll mutate much faster than fungi. (Don’t worry, there won’t be a pop quiz.)

But this is why fungal infections are often easier to treat, because the organism is slower to mutate and change, which means treatments can act quickly.
For example, the most common bacterial infection on the skin is a Staph infection, named after staphylococcus bacteria, the natural bacteria that lives on the skin. Staph infections can enter the bloodstream and cause a host of other, sometimes very serious, problems. Treating them might require prescription antibiotics.

On the other hand, fungal infections might present as an itchy patch that can be treated with a topical cream and dealt with in a few weeks. Of course, this is very, very generally speaking. For any skin condition that’s outside of the norm, have a doctor check it out to get a proper diagnosis. Neither should be left untreated.

Types of Fungal Infections

There are too many types of fungal infections to even count. These common fungal infections only begin to scratch the surface.

Athlete’s Foot

One of the most common fungal infections is athlete’s foot, or tinea pedis. As you might guess, it often occurs in athletes or people who find themselves barefoot in a shared space like a locker room, public showers, or pool deck. But it can also affect people who have sweaty or still-damp feet, who then wear shoes all day. Fungus grows in dark, damp spaces, so you can see where this is going. Athlete’s foot can be contagious, spreading on the locker room floor, but it can also show up of its own accord if the conditions are just right.

Athlete’s foot might start with an itch and look like a red rash. But if it grows, it might cause peeling, blisters, and scaliness on the feet, typically between the toes. Sometimes it might cover the entire sole, and other times it might just be a few small patches. Over-the-counter antifungal creams and sprays usually take care of it; while drying powders, and making sure to wash and really dry the feet before putting shoes and socks on, can help prevent it. (Skip ahead to see how you treat athlete's foot.)

Jock Itch

Jock itch, like athlete’s foot, isn’t named with subtlety. It’s medically known as tinea cruris, and yes, it primarily affects athletes, but that doesn’t mean only people who wear jerseys and drink sponsored Gatorade can get it. Anyone who’s sweating in the groin region, man or woman, can experience jock itch. It’s an itchy, red rash in the folds of skin in the groin area and inner thighs. It might peel and flake.

As with many fungal infections, it’s more common during warm and humid summer months, though it can happen at any time of year. Jock itch is usually caused by not changing workout clothes or failing to properly clean and dry the groin area during and after showering. In some cases, it might be caused by a contagious case of athlete’s foot. It could also be caused by sharing contaminated towels or clothing. But also like athlete’s foot, it can be easily treated with hydrocortisone and/or antifungal treatments, often labeled specifically for jock itch. More severe cases might require a prescription ointment or oral antifungal. (Skip ahead to see how you treat jock itch.)

Tinea Versicolor

Tinea versicolor is a common fungal infection that affects the normal pigmentation of the skin, hence the word “versicolor.” It results in small to large patches of discolored skin that might be lighter or darker than the surrounding area, though in most cases, the discoloration is lighter.

“Tinea versicolor is a common condition in the summer,” says Dr. Caren Campbell. “Yeast [on the skin] produces what’s called azelaic acid—which is used in a lot of cosmetics for helping with hyperpigmentation—and that azelaic acid interferes with pigment production, so it causes these little white patches on the skin.” Because the skin isn’t internally creating the melanin that gives skin its color, white patches of tinea versicolor won’t tan.

Oily skin and humid weather are among the greatest causes of tinea versicolor. It can be treated the same way as other fungal infections, with topical antifungal creams, dandruff shampoo used as a body wash, and prescription medication for more severe cases. (Read more on how you treat tinea versicolor.)

Fungal Acne

Fungal acne is one of the trickiest fungal infections to identify because of how similar it appears to acne, hence the nickname. But fungal acne isn’t a medical term, and it’s misleading because fungal acne isn’t related to acne at all—it’s a fungal infection caused by an overgrowth of yeast.

[Fungal acne is] not a thing. It doesn’t exist. It’s not a medical term.

—says explains Dr. Caren Campbell, a board-certified dermatologist in San Francisco, CA.

In most cases, she notes, people use “fungal acne” to refer to pityrosporum folliculitis, the medical term that indicates a fungal infection that’s clogging the hair follicles. But the nickname, thanks to social media, has stuck.

Pityrosporum folliculitis—fungal acne—causes small, uniform pimples that look like whiteheads in certain areas of the body, primarily the chest, back, or arms, and in rare cases, the face. Like other fungal infections, it can be red, inflamed, and itchy. It’s typically treated with sulfur washes, or ketoconazole dandruff shampoo used as a body wash.

Products used to treat acne (acne vulgaris) don’t work on fungal acne, because the cause of fungal acne is completely different. Pityrosporum folliculitis, fungal acne, is caused by an overgrowth of yeast, which can happen when there’s trapped moisture on the skin, say from sweaty workout clothes—or any sweaty/damp clothes—left on too long. It can also happen as a side effect of certain medications, or totally randomly, due to one’s unique body chemistry.

Fungal acne has a “monomorphic” distribution.

—notes Dr. Campbell, which means every tiny pimple-like bump is around the same size.

Acne vulgaris usually shows up with pimples of different sizes, scattered here and there, and they typically don’t itch. A dermatologist will be able to immediately spot the difference. (Read more on how you treat fungal acne.)

Intertrigo

Intertrigo is a general term for red, inflamed skin in areas where there are skin folds. But it can have a fungal component, notes Dr. Caren Campbell. “It’s like jock itch,” she explains. “[It can occur] in women who have larger breasts. You get these shiny, pink patches on the skin under the breasts, or in the groin fold of men.” The yeast overgrows in warm, moist areas, which is why it’s commonly found underneath the breasts, in the armpits, and groin.

It can be treated with antifungal topical creams, or oral medication, and prevented with over-the-counter drying powders, like Zeosorb, that help sweat from accumulating on those areas of the skin.

Dandruff (seborrheic dermatitis)

Seborrheic dermatitis usually refers to dandruff on the scalp, but it can also present as flaky patches in between the eyebrows, behind the ears, and elsewhere on the body. “A large percentage of the population has seborrheic dermatitis,” notes Dr. Caren Campbell. But despite how common it is—one study mentions half the population experiences it—doctors aren’t totally certain what causes it, though they believe there’s a fungal component.³ Fungus usually grows in damp, dark environments, but it can also grow in oily areas of the skin, like the scalp.

The typical treatment is an antifungal dandruff shampoo. But “it's a spectrum, just like anything in life,” Dr. Campbell says. Mild cases can be treated with over-the-counter shampoos like Selsun Blue, she notes, while “other patients, who might have oilier skin or for whatever reason, their genetic makeup predisposes them to more significant overgrowth of that yeast, might need prescription-strength antifungal shampoos, creams, pills, or topical agents.”

Onychomycosis

Although it sounds serious and is definitely hard to spell, onychomycosis is just a fungal nail infection. It’s more common on the toenails than fingernails, because toes are a better breeding ground for fungus (especially when hidden in socks), but it can occur in both areas.

Onychomycosis is usually identified by discolored nails that appear either yellow or brown. It can also cause the nails to thicken, or become brittle or painful to the touch.⁴ It can be caused from fungus overgrowth, athlete’s foot, unsterilized nail clippers, and the infection can become much worse in patients with diabetes, or who have blood circulation issues.

Because of the sensitive nature of this infection, prescriptions are usually necessary to treat it rather than over-the-counter antifungal creams.