Skin fungal infections are skin diseases caused by fungus, such as mold or mildew.
The most common types of fungus that affect the skin include:
- Yeast infections
- Candida
- Malassezia
- Seborrhoeic dermatitis
- Dermatophyte infections (ringworm)
- Tinea corporis (fungal infection of the scalp)
- Tinea cruris (“jock itch”)
- Tinea pedis (“athlete's foot”)
- Tinea capitis (fungal infection of the scalp)
- Tinea barbae (fungal infection of the beard)
- Tinea unguium (dermatophyte onychomycosis) (fungal infection of the nails)
General steps to take to treat and prevent skin fungal infections include:
- Keep affected skin clean and dry
- Ensure you dry thoroughly between the toes and in the skin folds; use a hair dryer if needed
- Do not share towels
- Clean the shower or bath using bleach
- Wash socks, towels, and bathmats at a temperature of at least 140°F (60°C)
Fungal spores can survive for long periods. Once the infection has gone away, steps you can take to reduce the chance of reinfection include:
- Keep skin clean and dry
- Dry off completely after showering or bathing
- Athletes involved in close contact sports should shower immediately after practice and keep sports gear clean
- Athletes should not share sports gear with others
- Don’t go barefoot in locker rooms or public showers
- Wear loose shoes that allow air to circulate freely around the feet
- Keep fingernails and toenails clean and trimmed short
- Do not share clothing, towels, sheets, or personal items with an infected person
- Wash hands with soap and water after playing with pets
Medical treatment for skin fungal infections includes:
- Over-the-counter (OTC) or prescription topical antifungal products
- Extensive or recurrent infections may require systemic (oral) antifungal therapy
What Are Symptoms of Skin Fungal Infections?
Symptoms of a yeast infection on the skin may include:
- Skin inflammation
- Itchy skin
- Moist skin
- Skin peeling or cracks in the skin
- Red and white skin
- Small superficial papules and pustules
- Secondary bacterial infection that may cause an unpleasant odor
Dermatophyte infections (ringworm) affect the skin, fingernails, and toenails. Symptoms of dermatophyte infections appear within 4 days to 2 weeks after coming into contact with the fungi that cause ringworm.
Symptoms of dermatophyte infections include:
What Causes Skin Fungal Infections?
Yeast infections are caused by a fungus called Candida albicans. Most people have a small amount of Candida on or in the body, but when it grows out of control it can develop into an infection.
Risk factors for developing a yeast infection include:
- A weakened immune system, such as from HIV or cancer treatment or other causes
- Obesity, especially in people who have large skin rolls where fungi can thrive
- Type 1 diabetes or type 2 diabetes
- Prolonged use of antibiotics
- Genetic tendency to skin disease
- Excessive sweating
- Age
- Smoking
- Alcohol
- In infants, exposure to sweat, urine, and feces in the diaper area
Ringworm is a skin condition caused by dermatophytes, a type of fungus that lives on the dead outer layer of skin. The condition is called “ringworm” because it can cause a circular rash shaped like a ring. There is no worm involved.
How Are Skin Fungal Infections Diagnosed?
To diagnose a yeast infection, a doctor will perform a physical exam.
Tests that may be used to help diagnose a yeast infection include:
- Swab of the vagina, penis, or skin for bacterial culture
- Skin scraping to culture fungi
- Skin biopsy if the skin condition is unusual or does not respond to treatment
Dermatophyte infections (ringworm) can often be diagnosed with a physical examination of the affected skin. Tests that may be indicated to diagnose ringworm include:
Skin scraping to be examined under a microscope or sent to a laboratory for a fungal culture
Ultraviolet light — can only diagnose two species: Microsporum canis and audouinii
From 
Skin Problems and Treatments Resources
https://www.uptodate.com/contents/dermatophyte-tinea-infections?search=fungal%20skin%20infection&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://dermnetnz.org/topics/fungal-skin-infections/
https://www.cdc.gov/fungal/diseases/candidiasis/index.html