Fungal infections

Medically reviewed by The Dermatologists and written by Dr. Alexander Börve

What are fungal infections

Fungal infections are caused by microscopic fungi that normally live harmlessly on the skin (skin commensals) but can sometimes overgrow and cause disease. They can affect different layers of your skin, mouth, and even internal organ systems. Heat, moisture, and immune system problems in conditions like HIV or cancer can increase the risk of fungal infections on various parts of the body.

• Candida (yeast infections): mouth, vagina
• Malassezia: scalp dandruff, hair follicles (fungal acne)
• Dermatophytes (ringworm): nails (tinea unguium), athlete’s foot (tinea pedis), scalp ringworm (tinea capitis), jock itch (tinea cruris)

Fungal infections can spread from person to person through direct contact, inhalation, sharing personal items like towels, or contaminated surfaces such as locker room floors.

Fungal infection with a red circular rash and small white bumps near the outer edge, diagnosed as Tinea Corporis (ringworm), a common superficial fungal infection

Symptoms

They can vary according to the type of fungal infection.

• Ringworms: Itchy, red, circular or oval shaped lesions with sharp, raised margins.^[3] Sometimes it might have small blisters as well. Center is clear and indented. The lesion spreads from center outwards, and the typical ring like appearance of dermatophyte infection gives its name ‘ringworm infection’^[3]
• Pityriasis versicolor: multiple oval reddish/white or dark colored patches on the skin with fine scaling^[4]
• Fungal nail infections: thickened, discolored and brittle toenails or fingernails. The nail plate might get elevated or completely detached from the nailbed as the infection progresses.^[5]
• Yeast infection of the vagina: itching and burning sensation of the vagina which becomes more prominent just before the menstrual period.^[6] Some people may get thick white vaginal discharge as well.
  If you’re unsure whether symptoms could be caused by another condition, see how lichen sclerosus differs from certain STDs.
• Oral thrush (yeast infection of the mouth): white or reddish lesions in the mouth, accompanied by soreness, burning, taste changes, or cracks at mouth corners.^[7] Some forms are painless, while others cause discomfort or swelling.
• If steroids are used, the typical appearance of the fungal infections will be lost, and there would be widespread lesions that are difficult to recognize as fungal infection.

Fungal infection on the buttocks with red, patchy rashes and darker spots, commonly seen in warm, moist areas.

Fungal infection in the nails (finger nail fungus) showing onychomycosis with visible damage and discoloration

Tinea versicolor on the trunk, close-up view showing reddish patches caused by a superficial fungal infection

Tinea versicolor on the trunk, focusing on red spots across the chest caused by a superficial fungal infection

inea versicolor on the trunk, focusing on red spots across the chest caused by a superficial fungal infection[/caption]

Not all rashes that look like a fungal infection are caused by fungi.
See pictures of the most common itchy rashes and their treatments to help understand possible differences.

Types of fungal infections

1. Tinea corporis (Ringworm)

Appears as red, circular or oval shaped lesions with sharp, raised margins and a flat, clear center.^[3] Most commonly seen on the exposed body parts like the neck, trunk, arms and legs. These ring-like round lesions can become widespread, merge together or spread out to involve a larger area, especially if you are immunocompromised.

2. Tinea pedis

A long-lasting itchy skin rash that appears in between toes, with peeling, softening and cracking of the skin involved. There can be reddening and finely scaling skin, with the occasional appearance of blisters on the sole of the foot. It is very discomforting, and simultaneous bacterial infections can worsen the condition by ulcer formation.^[8]

Learn more about treating nail infections and foot fungus.

3. Tinea cruris (jock itch)

Itchy red ring-shaped rash in the groin, inner thighs or buttocks that may cause irritation, pain, or discomfort if severe. Heat, sweating, tight clothing, and poor hygiene increase the risk, and subsequent bacterial infections can worsen the rash.^[9]

4. Tinea Unguium (Nail Fungus/Onychomycosis)

Fungal nail infection causes nails to become thick, brittle, and often cause yellowish discoloration. As it worsens, the nail may lift from the nailbed or even detach entirely, often affecting toenails more than fingernails.^[5]

5. Tinea versicolor

A very common yeast infection of the most superficial layer of the skin that often doesn’t cause discomfort. Usually appear as multiple oval reddish/white or dark colored patches on the trunk, neck, and with fine scaling.^[4] Often the lesions become more prominent after getting exposed to the sun.

6. Candidiasis (Yeast infection)

Yeast infections can appear in your mouth, vagina, penis and the skin of other body parts, and has a risk of infecting inner organs. It can cause white or red patches, soreness, or thick plaques in the mouth.^[7] There is an increased risk of getting candida infection if you are on antibiotics, steroids, dentures, or have poor oral hygiene. Vaginal candidiasis can present with itching in the genital area, burning sensation and white discharge form the vagina that typically has a cottage cheese like consistency.^[6]

Experiencing persistent itching or redness on your skin? Noticing unusual rashes, scaling, or discomfort? These could be signs of a fungal infection that requires prompt attention.

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Who Is at Risk of Fungal Infections?

Fungal infections can affect anyone, but certain factors increase the risk:

• Weakened immune system — for example, due to HIV infection, diabetes, or cancer treatments such as chemotherapy.

• Hot and humid environments — excessive heat and moisture encourage fungal overgrowth.

• Tight, non-breathable clothing — traps sweat and heat, creating ideal conditions for fungi.

• Recent antibiotic or steroid use — can disrupt normal skin and gut flora.

• Age-related vulnerability — higher risk in children, elderly individuals, and pregnant women.

• Poor hygiene practices — infrequent washing or not keeping skin dry.

• Excessive sweating — common in athletes and people doing heavy physical work.

How to diagnose

While some fungal infections have a characteristic appearance which may help you correctly identify them, others can be trickier and need medical attention. Visual examination is the first step to diagnosis. This can be done in person, or via image based online services such as First Derm, that offer their diagnostic services free of charge. There are certain tests your healthcare provider might suggest in order to confirm diagnosis. These tests include:

• Skin scraping with potassium hydroxide (KOH) test: skin scrapings are collected from the skin lesion, stained and looked under the microscope to identify the fungal species.
• Dermoscopic examination: identify the characteristic features of tinea infections (eg: corkscrew hairs in tinea capitis)^[3]
• Wood’s lamp for scalp fungal infections: look for the fluorescence of the infected areas

Fungal culture: very reliable and specific method that takes up to 4 weeks to get the results. Skin scrapings, material under the infected nails are collected and grown in special culture media, and the subsequent analysis of the appearance, color and the spread of the colonies help arrive at a diagnosis.^[3]

Treatment options

When to seek medical help

Even though most fungal infections appear quite harmless, they can cause significant discomfort if they spread or become inflamed. The best option is to seek medical attention early, so that an accurate diagnosis and proper treatment can give you quick relief.

See a doctor if:

• The rash spreads, oozes, or worsens, especially with over-the-counter treatments you have tried.

• Symptoms persist beyond 2 weeks despite what you have tried.

• You have a weak immune system, diabetes, or cancer — fungal infections can be more aggressive in these cases.

• There is nail involvement or a scalp infection.

• You are unable to decide if it is a fungal infection — a proper diagnosis is important before starting treatment.

Why this matters:

It is better to establish a proper medical diagnosis before starting treatment rather than using a trial-and-error method, which might end up worsening the rash.

How to Prevent Fungal Infections

Personal hygiene plays a major role in prevention.

Daily habits to follow:

• Stay clean and dry, paying extra attention to drying skin folds after washing.

• Wear loose-fitting, breathable clothes to avoid trapping moisture.

• Do not share personal items like towels or razors, which can carry fungi from person to person.

• Use barriers when touching contaminated surfaces (e.g., wear flip flops in locker rooms or public showers).

• Wash and dry between your toes daily to prevent moisture build-up.

• If you use steroid inhalers, rinse your mouth thoroughly after each use to avoid candida infections of the mouth.

A little effort in self-care can go a long way. Investing in your hygiene practices helps protect against fungal infections and supports overall skin health.

Medical Disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health. Do not ignore or delay seeking medical advice because of information found here.