ConditionInfections
Fungal Infections
Fungal infections (mycoses) are infections caused by fungi, including yeasts and molds. Most are superficial: common, mild infections of the skin, nails, mouth or vagina, such as athlete's foot, ringworm, nail fungus, thrush and vaginal yeast infections, treated with creams or short courses of tablets. Less often, fungi cause deep or invasive infections of the lungs, blood or brain, mainly in people with weakened immune systems or after inhaling spores in certain regions. These need prompt specialist treatment.
Also called: Mycoses, fungal disease, mycotic infection, yeast infections, tinea
At a glance
- What they are
- Infections caused by yeasts or molds.
- Superficial (common)
- Ringworm, athlete's foot, jock itch, nail fungus, scalp ringworm, tinea versicolor, thrush, vaginal yeast.
- Endemic (regional)
- Valley fever, histoplasmosis, blastomycosis, from inhaled spores in soil.
- Opportunistic (serious)
- Invasive candidiasis, aspergillosis, cryptococcosis, mucormycosis, Pneumocystis pneumonia.
- Diagnosis
- Appearance; skin scrapings, cultures, blood tests, imaging for deep infections.
- Treatment
- Topical or oral antifungals; IV antifungals for invasive disease.
When to get help
Call 911 or go to the ER
- Fever with confusion, severe headache or stiff neck in someone with HIV or a weak immune system (possible cryptococcal meningitis)
- Black, crusted tissue in the nose or on the face with facial swelling, especially with uncontrolled diabetes (possible mucormycosis)
- Fever and low blood pressure in a hospitalized or immunocompromised person
See a doctor within a day or two
- Cough, fever and breathlessness in someone on chemotherapy, after a transplant, or on high-dose steroids
- White patches in the mouth with pain on swallowing (possible esophageal thrush)
- Pneumonia-like illness after travel or digging in the US Southwest or Ohio and Mississippi river valleys that is not improving
Book a routine appointment
- Itchy, scaly rash that does not clear after 2 to 4 weeks of over-the-counter antifungal cream
- Thick, discolored nails
- Recurrent vaginal yeast infections (4 or more a year)
- Scaly scalp patches with hair loss in a child
Usually safe to manage at home
- Mild athlete's foot, jock itch or ringworm patch
- A typical vaginal yeast infection in someone who has had one diagnosed before
How fungi cause infection
Fungi live everywhere: in soil, on plants, in the air and on our skin. Most are harmless. Infection happens when:
- skin is warm, moist or damaged, allowing dermatophytes (skin fungi) to grow
- the normal balance of microbes is disturbed, for example by antibiotics, allowing Candida yeast to overgrow
- spores are inhaled in large numbers
- the immune system is weakened, allowing normally harmless fungi to invade deeper tissues
Fungal infections are generally not as contagious as viral or bacterial infections, though skin and scalp infections spread through contact and shared items.
Superficial fungal infections
| Infection | Where | Signs |
|---|---|---|
| Ringworm (tinea corporis) | Body | Red, scaly ring with a clearer center, itchy |
| Athlete's foot (tinea pedis) | Feet, between toes | Itching, peeling, cracking |
| Jock itch (tinea cruris) | Groin, inner thighs | Red, itchy rash with a raised edge |
| Nail fungus (onychomycosis) | Toenails, fingernails | Thick, yellow, crumbly nails |
| Scalp ringworm (tinea capitis) | Scalp, mostly children | Scaly patches, hair loss |
| Tinea versicolor | Chest, back | Light or dark patches, mild scaling |
| Oral thrush | Mouth | White patches that wipe off, soreness |
| Vaginal yeast infection | Vagina, vulva | Itching, thick white discharge, burning |
| Intertrigo with candida | Skin folds | Red, moist rash with satellite spots |
| Fungal ear infection | Ear canal | Itching, discharge, blockage |
Endemic fungal infections
These are caught by inhaling spores from soil in specific regions:
- Valley fever (coccidioidomycosis): US Southwest (Arizona, California), Mexico. Flu-like illness, cough, rash, fatigue lasting weeks.
- Histoplasmosis: Ohio and Mississippi river valleys; bird and bat droppings. Often mild; can be serious in immunocompromised people.
- Blastomycosis: Midwest and Great Lakes areas. Lung infection, skin lesions.
Opportunistic and invasive infections
- Invasive candidiasis: Candida in the blood or organs, mainly in hospitalized patients with central lines, surgery or ICU stays. Candida auris is a drug-resistant species causing hospital outbreaks.
- Aspergillosis: from inhaled Aspergillus mold. Ranges from allergic reactions in people with asthma to life-threatening lung infections in those with leukemia or transplants.
- Cryptococcosis: lung and brain infection, especially in advanced HIV.
- Mucormycosis: rare, aggressive infection of the sinuses, face or lungs, linked to uncontrolled diabetes and immune suppression.
- Pneumocystis pneumonia (PCP): in people with HIV or on immune-suppressing medicines.
Risk factors
- warm, humid environments; sweaty feet; shared showers and gyms
- diabetes, especially when poorly controlled
- antibiotics, steroids (including inhaled steroids for thrush) and immune-suppressing medicines
- pregnancy and hormonal contraception (vaginal yeast)
- obesity and skin folds
- HIV, cancer treatment, organ or stem cell transplant
- ICU stays and central lines
Diagnosis
- Skin, nail and hair: examination, potassium hydroxide (KOH) scraping under a microscope, fungal culture, sometimes a Wood's lamp.
- Mouth and vagina: examination and swabs.
- Deep infections: blood cultures, antigen tests (such as cryptococcal antigen, galactomannan for Aspergillus), antibody tests for endemic infections, chest CT, biopsy.
Treatment
Superficial infections
- Topical antifungals such as terbinafine, clotrimazole, miconazole or ketoconazole for skin infections, usually 1 to 4 weeks and continued for 1 to 2 weeks after the rash clears.
- Oral antifungals (terbinafine, itraconazole, fluconazole, griseofulvin) for nail, scalp and widespread infections.
- Vaginal yeast: over-the-counter vaginal creams or a prescription single-dose oral fluconazole.
- Oral thrush: antifungal lozenges, gels or oral fluconazole.
Oral antifungals can interact with many medicines and occasionally affect the liver, so a doctor or pharmacist should review them.
Invasive infections
Intravenous or oral antifungals such as echinocandins, voriconazole, posaconazole, isavuconazole or amphotericin B, often for weeks to months, plus reduction of immune suppression where possible and surgery for some infections.
Prevention
- Keep skin clean and dry, especially feet and skin folds.
- Wear sandals in communal showers and change socks daily.
- Do not share towels, combs or nail clippers.
- Treat pets with ringworm.
- Rinse your mouth after using steroid inhalers.
- Control blood sugar.
- In endemic areas, reduce dust exposure, and wear masks when cleaning bird or bat droppings.
- People with severe immune suppression may be prescribed preventive antifungals.
Frequently asked questions
What are the most common fungal infections?
The most common are athlete's foot, jock itch, ringworm, nail fungus, tinea versicolor, oral thrush and vaginal yeast infections. They affect the skin, nails and mucous membranes and are usually treated easily with creams or short courses of tablets.
How do I know if I have a fungal infection?
Fungal skin infections usually cause itching and a red, scaly rash, often ring-shaped or in warm, moist areas, spreading slowly. Nail fungus thickens and discolors nails. Yeast infections cause white patches or thick white discharge. A doctor can confirm it with a scraping or swab.
Are fungal infections contagious?
Some are. Ringworm, athlete's foot, jock itch and scalp ringworm spread through skin contact, shared items and pets. Yeast infections are usually not considered contagious. Endemic and invasive fungal infections do not spread between people.
How long does it take to cure a fungal infection?
Skin infections usually clear in 2 to 4 weeks with antifungal cream. Nail fungus takes 3 to 12 months, because the nail must grow out. Invasive infections can need weeks to months of treatment.
Can fungal infections be serious?
Most are mild. But invasive fungal infections of the lungs, blood or brain can be life-threatening, mainly in people with HIV, cancer treatment, transplants, uncontrolled diabetes or long ICU stays. These require urgent specialist care.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Fungal diseases; Types of fungal diseases
- Infectious Diseases Society of America (IDSA): Clinical practice guidelines for candidiasis and aspergillosis
- American Academy of Dermatology: Tinea infections
- MedlinePlus: Fungal infections
- World Health Organization: Fungal priority pathogens list