Fungal skin infections, also known as fungal dermatitis, mycosis, or tinea, are very common. Fungi can infect the skin, nails, and hair. Some types of fungal skin infections include athlete’s foot, jock itch, ringworm, and candidiasis. Fungal skin infections can cause irritation, itching, redness, peeling skin, rashes, and other symptoms. Diagnosing fungal skin infections usually involves a physical exam of the affected area and a skin sample for laboratory testing if needed.
What are the symptoms of a fungal skin infection?
There are several different types of fungal skin infections, each with their own unique symptoms:
- Athlete’s foot causes itching, stinging and burning between the toes. The skin may peel, blister, scale and crack.
- Jock itch causes a red, itchy rash in the groin area that may spread to the inner thighs.
- Ringworm causes a red, circular rash with clearer skin in the middle. Itching and burning may occur.
- Yeast infections like candidiasis cause itchy red patches with satellite lesions around the edges. Moist areas are commonly affected.
- Nail fungus can cause nails to become discolored, thickened, brittle, or separated from the nail bed.
- Scalp ringworm causes bald patches and scaly skin on the head.
In general, look for itchy, red, scaly patches on the skin, especially between the toes, groin, scalp, hands, and nails. The rash may be circular with central clearing. See your doctor if you have any suspicious rashes that don’t clear up within a couple weeks.
Who is at risk for fungal skin infections?
Certain groups have an increased risk of developing fungal skin infections:
- Athletes – The warm, moist environment caused by sweating increases risk of fungi like athlete’s foot.
- Overweight or obese individuals – Fungal infections can thrive in skin folds.
- People with diabetes or weakened immune systems – High blood sugar and impaired immunity increase susceptibility.
- Older adults – Immune function and skin integrity decline with age.
- People who share showers or locker rooms – Fungi spread more easily in warm, damp public areas.
- People who wear tight shoes or clothes that don’t allow skin to breathe – This creates a warm, moist environment fungi like.
Practicing good hygiene, keeping skin dry, wearing loose-fitting clothing, and treating underlying conditions can help reduce your risk.
When to see a doctor
See your doctor if:
- You have signs of a fungal infection that persists for more than 2 weeks
- The rash is widespread, painful or getting worse
- You have diabetes, a weakened immune system or other underlying medical condition
- OTC antifungal creams haven’t improved the rash
- You are unsure if the rash is fungal or caused by something else
Getting prompt treatment can help prevent complications and spread to other areas of the body. People with weakened immune systems are also at risk of the infection spreading internally if not treated.
Physical Exam
During a physical exam, the doctor will inspect the rash and ask about your symptoms. Features they’ll note include:
- Location of the rash
- Color and texture – scaling, crusting, bumps, blisters etc.
- Border – some fungal infections like ringworm have a circular lesion
- Number of lesions – a single patch vs multiple patches throughout the body
- Appearance of the skin around the rash
- Involvement of hair follicles or nails
- Signs of inflammation like swelling, redness, heat
- Presence of pus, discharge or any openings in the skin
Your medical history is also important, including any prior fungal infections, other skin conditions like eczema or psoriasis, medications, and illnesses or immune deficiencies.
Skin Exam Techniques
Some examination techniques your doctor may use include:
- Visual inspection under room lighting and with a wood’s lamp, which uses ultraviolet light.
- Touching the lesion to feel for scaling, moisture, raised borders or discharge.
- Gently scraping the edge of the lesion with a sterile blade to check for pus.
- Observing hairs under a microscope for evidence of fungal infection.
- Pressing the lesion to check for any tenderness or discomfort.
The physical exam gives your doctor clues about the type of fungal infection and whether fungal testing is needed.
Types of Fungal Tests
If the diagnosis remains uncertain after the exam, your doctor may collect a skin or nail sample to identify the specific type of fungus causing infection. Fungal tests include:
- Potassium Hydroxide (KOH) Preparation – Skin, nail or hair specimens are placed in a KOH solution and examined under a microscope for presence of fungal elements.
- Fungal Culture – The sample is placed on a special medium in a petri dish to allow growth of the fungus, which is then identified.
- Biopsy – A small sample of the affected skin or nail is collected and examined under a microscope.
- Polymerase Chain Reaction (PCR) – Advanced techniques like PCR can detect small amounts of genetic material from fungi.
Knowing the specific species of fungus helps guide treatment.
How to Prepare for Fungal Testing
Certain steps may improve the accuracy of fungal testing:
- Avoid applying any topical antifungal creams for 1-2 weeks before the test.
- Carefully wash and dry the affected area before the test.
- Trim down thickened nails to allow better collection of nail specimens.
- Note the location and appearance of any rashes.
- Inform your doctor about any medications, weakened immunity or other medical conditions.
Proper preparation allows for a good quality specimen to be obtained for testing. Let your doctor know if you have any issues collecting the sample.
Collecting Skin and Nail Samples for Fungal Testing
Skin or nail specimens may be collected in the doctor’s office or through an at-home collection kit. Here is how fungal skin and nail samples are obtained:
Skin Scrapings
After cleaning the area with alcohol, the edge of the affected skin will be gently scraped with a sterile blade to collect tissue flakes and skin cells. Several samples may be taken from different areas. The scrapings are placed on a slide for KOH preparation.
Skin Biopsy
Using a small punch tool, the doctor extracts a tiny core of the infected skin, about the size of a pencil tip. The skin biopsy is sent to the lab for examination under a microscope.
Nail Clippings
Small clippings are taken from the discolored or brittle part of the nail using sterile nail clippers or a scalpel. Clippings may be collected from several nails. They are placed in KOH solution or sent for fungal culture.
Hair Samples
Around 6-10 infected hairs may be plucked from the scalp by firmly gripping the hair close to the scalp and pulling up. The doctor looks for evidence of fungal infection around the hair shaft and root.
At-home sample collection kits include a brush or toothpick used to obtain tissue from under the nails. Your doctor provides instructions on properly collecting and mailing the sample to the lab.
Interpreting Fungal Test Results
Here is how fungal test results are interpreted:
KOH Preparation
- Positive – Threadlike hyphae or budding yeast structures visible under the microscope indicate fungal infection.
- Negative – No fungal elements seen.
Fungal Culture
- Positive culture – Growth of fungal colonies identifies the specific species causing infection.
- Negative culture – No fungal growth after 4-6 weeks likely rules out a fungal infection.
Skin Biopsy
- Positive – Fungal hyphae or spores visible in the skin sample under the microscope.
- Negative – No signs of fungus seen.
Discuss any positive results with your doctor to guide antifungal treatment. A negative culture or biopsy is helpful to rule out fungal infection and explore other potential causes for the skin symptoms.
Benefits of Laboratory Fungal Testing
There are several advantages to getting a skin or nail specimen tested in the lab for fungus:
- Confirms whether a fungal infection is present.
- Identifies the particular species of fungus causing infection.
- Guides selection of the most effective antifungal medication.
- Provides an accurate diagnosis when the infection is unclear clinically.
- Aids in monitoring response to treatment over time.
- May help detect drug-resistant fungal infections.
- Rules out fungal infection and other potential causes can be explored.
Lab tests are especially useful when OTC antifungals haven’t resolved the symptoms, the rash has an unusual appearance, or you have a high-risk condition like diabetes or immunodeficiency.
At-Home Self-Testing for Fungal Infections
While laboratory tests are more accurate, some at-home self-testing options for fungal skin infections are available, including:
- Black Light Inspection – Certain fungi glow green under ultraviolet black light.
- Magnifying Glass Exam – Scaling and blisters caused by fungus may be visible with 10x magnification.
- Skin Scraping with KOH – A kit allows skin flakes to be examined under a microscope after KOH application.
- Fungal Culture Kit – A sample can be collected at home and mailed to the lab for culture.
While convenient, at-home testing has limitations. Lab tests are still recommended for definitive diagnosis. Inform your doctor if using any self-tests.
Treatment for Fungal Skin Infections
After confirming diagnosis, fungal skin infections are treated with topical or oral antifungal medications:
Topical Antifungals
Creams, ointments, powders, and sprays applied to the skin may include:
- Clotrimazole (Lotrimin, Mycelex)
- Miconazole (Monistat, Micatin)
- Terbinafine (Lamisil)
- Ketoconazole (Nizoral)
- Ciclopirox (Loprox)
- Tolnaftate (Tinactin)
Follow directions for application amount, frequency, and duration of use.
Oral Antifungal Medication
Pills, tablets or capsules that treat infection internally may be prescribed for widespread, severe or resistant fungal infections. These include:
- Terbinafine
- Itraconazole (Sporanox)
- Fluconazole (Diflucan)
- Griseofulvin
Take the full course as directed. Avoid alcohol when using oral antifungals. Notify your doctor of any side effects.
Treatment length depends on the type and severity of the fungal infection. Mild cases may resolve in a few weeks with topical creams. More extensive fungal infections require longer treatment, typically 4-12 weeks. Stick with antifungal therapy even after symptoms improve to ensure the infection is fully cleared.
Home Remedies and Lifestyle Tips
In addition to medical treatment, try these home remedies to help clear fungal skin infections:
- Wash the affected skin twice daily using antibacterial soap and dry thoroughly.
- Apply over-the-counter antifungal powders after drying the area.
- Use an antifungal shampoo for scalp infections.
- Trim and file down thickened nails.
- Wear loose, breathable clothing and socks.
- Avoid sharing towels, clothing, or shoes with others.
- Disinfect bathrooms, locker rooms, and showers regularly.
- Apply antifungal foot spray inside shoes.
Good hygiene helps prevent recurrence and spread. Keeping the skin dry deprives fungi of the moist environment they need to grow.
Preventing Fungal Skin Infections
You can take these preventive measures to avoid fungal skin infections:
- Wear shower shoes in public locker rooms and pools.
- Change socks and underwear daily.
- Avoid sharing personal care items like towels and razors.
- Wear breathable fabrics like cotton and linen.
- Avoid walking barefoot in warm public places.
- Treat athlete’s foot promptly to avoid spreading to the groin or nails.
- Keep skin clean and dry, especially between toes and skin folds.
- Apply antifungal powder to feet to absorb moisture.
- Clip toenails short straight across to avoid ingrown nails.
- Treat any underlying conditions like diabetes or weakened immunity.
Practicing good foot and skin hygiene prevents fungi from taking hold. See your doctor for stubborn fungal infections.
When to Seek Medical Care
Consult your doctor right away if you have:
- Persistent rash not improving with OTC antifungals after 2 weeks
- Rash that is painful, oozing or rapidly worsening
- Fever, swollen lymph nodes or other signs of infection
- Suspected fungal infection in someone with HIV/AIDS or organ transplant
- Fungal infection affecting multiple body areas
- Very thickened, distorted or discolored nails
- Scalp ringworm unresponsive to antifungal shampoo
Seek prompt medical advice for widespread, worsening or unusual fungal infections. Treatment prevents complications.
Complications of Untreated Fungal Infections
Without treatment, fungal skin infections may lead to problems like:
- Persistent itching and discomfort
- Secondary bacterial infections
- Permanent nail deformities or nail loss
- Hair loss with scalp infections
- Spread to other body areas, organs, and bones
- Chronic plaque-like candida lesions in skin folds
In people with weakened immunity, fungi can disseminate through the bloodstream and cause serious internal infections. Seek prompt medical treatment.
Conclusion
Fungal skin infections are diagnosed through a medical history, physical exam of the rash, and fungal testing of skin or nail samples if needed. Microscopic tests and fungal cultures help identify the species to guide treatment. Topical creams, oral medications, and good hygiene practices help clear fungal infections. See your doctor promptly for severe, persistent or unusual fungal rashes. With treatment, most fungal skin problems can be cured and recurrences prevented.