Image: Keeping feet dry, especially between the toes, can help reduce the risk of athlete’s foot. AI-generated illustrative image, not a clinical photograph.
An itchy foot, a changing toenail and a sore mouth can all involve fungi, but they need different care. Fungal infections range from common surface infections to much less common illnesses affecting the lungs, bloodstream or other organs. Knowing which fungus is involved and where it is growing helps determine the right treatment. CDC: About fungal diseases
Keeping feet dry, especially between the toes, can help reduce the risk of athlete’s foot. AI-generated illustrative image, not a clinical photograph.
What causes a fungal infection?
Fungi include yeasts and molds. Some live naturally on our skin or inside parts of the body without causing harm. Others are found in soil, dust, plants and animals. Infection can develop after exposure or when a normally harmless fungus grows too much.
Fungal infections can affect anyone. Having one is not a reason for shame or a reliable sign of poor hygiene. Moisture, skin contact, medicines, underlying health conditions and environmental exposure can all play a part. CDC: Fungal disease risk factors
1. Dermatophyte infections: ringworm, athlete’s foot and related conditions
Dermatophytes are fungi that infect the outer skin, hair and nails. These infections are often called tinea. Despite its name, ringworm is caused by a fungus, not a worm. It can spread through contact with an infected person or animal, or through shared items and surfaces. CDC: Clinical overview of ringworm
The name changes with the body site:
On a smaller screen, swipe or scroll sideways within the table to see every column.
| Site | Common name | Possible signs |
|---|---|---|
| Body skin | Tinea corporis, or ringworm | An itchy, scaly patch, sometimes with a raised ring-shaped edge |
| Feet | Tinea pedis, or athlete’s foot | Peeling, itching or cracks between the toes; scaling may also affect the soles |
| Groin and inner thighs | Tinea cruris, or jock itch | An itchy, scaly rash in the groin folds |
| Scalp | Tinea capitis | Scaling, broken hairs and patches of hair loss |
| Beard area | Tinea barbae | Inflamed, scaly or crusted patches around beard hairs |
| Hands | Tinea manuum | Dry, scaly skin, often on a palm |
| Nails | Tinea unguium, a form of onychomycosis | Thickened, discolored, brittle or lifting nails |
Not every infection forms a neat ring. On darker skin, inflammation may look brown, purple or gray rather than bright red. Nail changes can also result from injury or other skin conditions, so appearance alone does not confirm fungus. CDC: Ringworm symptoms; WHO: Ringworm
General treatment: A suitable antifungal cream can treat many limited skin infections. Scalp and beard infections usually require prescription treatment taken by mouth; shampoo or cream alone will not clear infected hair. Nail infection needs confirmation and may require topical or oral treatment, depending on its extent. Healthy-looking nails return slowly as the nail grows. CDC: Ringworm treatment; American Academy of Dermatology: Diagnosis and treatment
2. Candida infections: mouth, genitals and skin folds
Candida is a yeast that normally lives in and on the body. Overgrowth can cause candidiasis at several sites:
- Mouth and throat, or oral thrush: White patches, soreness, altered taste or cracking at the corners of the mouth.
- Esophagus, the swallowing tube: Painful or difficult swallowing. This needs medical assessment, especially with a weakened immune system.
- Vulva and vagina: Itching, soreness, discomfort during urination or sex, and a change in discharge. These symptoms also occur with other conditions, so repeated self-treatment can miss the real cause. CDC: Candidiasis symptoms
- Moist skin folds: A sore, inflamed rash beneath the breasts, in the armpits, under abdominal folds or in the groin, sometimes with small spots around its edge. Not every skin-fold rash is fungal. DermNet: Candidal intertrigo
Antibiotics, diabetes, pregnancy, dentures, inhaled corticosteroids and a weakened immune system can increase risk, depending on the site. Vaginal candidiasis is common in otherwise healthy people and is not usually acquired through sexual intercourse. CDC: Candidiasis risk factors; CDC: Vulvovaginal candidiasis
General treatment: Treatment may be a skin cream, a vaginal preparation, a medicine used inside the mouth or a prescribed oral antifungal. Esophageal infection needs systemic treatment. The formulation must match the site; a skin cream should not be put into the mouth or eyes. Pregnancy, recurring symptoms and a weakened immune system require particular care in choosing treatment. CDC: Candidiasis treatment
3. Malassezia infection: pityriasis versicolor
Pityriasis versicolor, also called tinea versicolor, is caused by overgrowth of Malassezia, a yeast normally found on skin. Despite the name “tinea,” it is different from dermatophyte ringworm.
It usually causes finely scaly patches on the chest, back, neck or upper arms. Patches may be lighter or darker than the surrounding skin, or pink. Itching is often mild or absent. Warm, humid weather and sweating can encourage it.
This condition is not generally considered contagious. Antifungal washes, shampoos or creams often help; widespread or persistent cases may need prescribed oral treatment. Skin color can take weeks or months to return after the yeast has been controlled, and recurrence is common. Persistent color change alone does not prove that treatment failed. DermNet: Pityriasis versicolor
4. Deeper skin infections and infections of the eye
Some fungi enter through a cut or puncture rather than simply growing on the skin surface. Sporotrichosis, for example, can follow contact with contaminated plant material or an infected animal. It may cause a persistent bump followed by additional nodules or sores, sometimes extending along an arm. It needs diagnosis and prescription treatment, often for a prolonged period. CDC: Sporotrichosis
Fungi can also infect the cornea or structures inside the eye. These infections are uncommon but can threaten sight. Eye pain, light sensitivity or blurred vision requires urgent assessment, especially after an eye injury. Do not use ordinary skin antifungal products in the eye. CDC: Fungal eye infections
5. Lung, bloodstream and other invasive fungal infections
These are different from routine athlete’s foot or thrush. Many occur in people with major risk factors, although some environmental fungal infections also affect otherwise healthy people.
- Endemic fungal lung infections: Histoplasmosis, coccidioidomycosis (Valley fever) and blastomycosis follow exposure to fungi found in particular regions. Breathing in spores can cause pneumonia. Tell your clinician about travel, soil or dust exposure, and a cough or fever that is not improving with usual treatment. CDC: Fungal pneumonias
- Aspergillosis: Aspergillus can cause allergic or chronic lung disease and, in people with weakened defenses, an invasive infection that can spread. Risk and treatment differ between these forms. CDC: Aspergillosis
- Invasive candidiasis: Candida can infect the bloodstream and internal organs, especially during serious illness, hospitalization or treatment involving invasive devices. An ordinary vaginal yeast infection does not mean someone has invasive candidiasis. CDC: Invasive candidiasis
- Cryptococcosis: This can affect the lungs and the tissues surrounding the brain and spinal cord, causing meningitis. Headache, fever and confusion are important warning signs. CDC: Cryptococcosis symptoms
- Mucormycosis: A rare, rapidly serious infection that can affect the sinuses, eyes, brain, lungs or injured skin. People with major immune suppression or poorly controlled diabetes are among those at risk. CDC: Clinical overview of mucormycosis
These illnesses need prompt specialist assessment. Treatment may involve oral or intravenous medicines, management of underlying risk factors and, for some infections, surgery. A cream cannot treat an internal fungal infection. NHS: Antifungal medicines
How is the diagnosis confirmed?
The test depends on the suspected infection and body site:
- Skin, hair or nails: A small scraping, hair sample or nail clipping may be examined under a microscope, cultured or tested with a molecular test.
- Mouth or vagina: Examination and, when needed, a swab or sample for microscopy or culture. Finding Candida without symptoms does not always mean treatment is needed.
- Lungs or internal organs: Tests may include blood or urine tests for fungal markers or antibodies, cultures, imaging, and sometimes a tissue or fluid sample.
There is no single test for every fungal infection. Results must be interpreted alongside symptoms and risk factors. WHO: Ringworm diagnosis; CDC: Candidiasis testing; CDC: Histoplasmosis testing
Two treatment mistakes to avoid
Do not use steroid cream on an undiagnosed scaly rash. Steroids can temporarily reduce redness while allowing ringworm to spread or become harder to recognize. Avoid casually using combined steroid-antifungal creams, including “triple combination” products. Get the diagnosis checked rather than repeatedly switching creams. CDC: Ringworm treatment
Do not start or repeat oral antifungals on your own. The wrong medicine may not work, can interact with other drugs and can sometimes harm the liver. Pregnancy, breastfeeding, other illnesses and current medicines affect which treatment is suitable. Use the correct product for the full directed course. NHS: Antifungal medicines
When to seek medical help
Seek emergency care for severe breathing difficulty, confusion, a severe headache with fever or neck stiffness, or rapidly worsening facial swelling with visual symptoms. A rapidly spreading painful wound, especially with dark or black tissue, also needs immediate assessment. These signs can have several serious causes, not only fungi. CDC: Cryptococcosis symptoms; CDC: Mucormycosis symptoms
Contact your treating team promptly if you are receiving chemotherapy, have had a transplant, have advanced HIV or take immune-suppressing medicines and develop fever, a new cough or another possible infection. Follow any urgent fever instructions your team has given you. CDC: Fungal disease risk factors
Arrange an assessment for suspected scalp or nail infection, widespread or recurring symptoms, a rash that worsens or fails to improve with appropriate treatment, or painful swallowing. People with diabetes should have foot cracks, wounds or signs of infection checked early. CDC: Ringworm treatment; CDC: Candidiasis testing; CDC: Ringworm and nail infection complications
Everyday prevention
- Dry skin folds and the spaces between the toes after washing.
- Change damp socks and clothing, and let shoes dry between uses.
- Wear footwear in shared showers and changing rooms.
- Avoid sharing towels, combs, footwear or nail tools.
- Have a pet with a suspicious skin patch checked by a veterinarian. CDC: Ringworm prevention
- Maintain oral and denture care, and rinse your mouth after using an inhaled steroid as directed. Do not stop prescribed steroids or antibiotics without medical advice. CDC: Preventing candidiasis
The useful first step is identifying the site and cause. Most common superficial infections are treatable, but different fungi need different medicines. Early assessment matters when the scalp, nails, eyes or internal organs are involved, or when the immune system is weakened.
This article provides general health education and cannot diagnose an individual condition or replace care from a qualified healthcare professional.
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