Ringworm Causes, Signs on Different Skin Tones, and Treatment

Ringworm is a skin infection caused by a fungus easily recognized by a circular, ring-shaped rash. The rash looks red on lighter skin, while ringworm on African-American skin or darker complexions may appear brown or grey.

Children are especially susceptible to ringworm. It is highly contagious and spreads easily by skin-to-skin contact, meaning you can get it by touching the rash of someone who is infected. Ringworm can also be passed from animals and pets, especially puppies and kittens. It is even possible to get ringworm from objects (by sharing hats, for example).

This article will explain how to recognize, treat, and prevent ringworm. It also covers rare serious complications of this common fungal skin disease.

Types of Ringworm

Ringworm is so-named because of its circular shape. Also known as tinea or dermatophytosis, it is a fungal infection that can affect the skin, hair, and nails. It has nothing to do with worms.

Ringworm is also named by where on the body it appears, such as:

• Tinea corporis affecting the torso, legs, and arms
• Tinea pedis, also known as athlete's foot, affecting the feet
• Tinea cruris, also known as jock itch, affecting the groin, inner thighs, or buttocks
• Tinea capitis affecting the scalp, back of the next, and behind the ears
• Tinea barbae affecting the beard
• Tinea manuum affecting the hands
• Tinea unguium, also known as onychomycosis, affecting toenails and fingernails
  

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This photo contains content that some people may find graphic or disturbing.

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Ringworm Symptoms on Different Skin Tones

Ringworm isn't hard to recognize once it develops its characteristic circular rash. Sometimes, though, ringworm symptoms can be confused with other skin rashes.

On most parts of the body, ringworm starts out as a flat, scaly lesion that gradually develops a border before extending outward to create a circular ring shape.

The border of the rash is usually raised and scaly, while the central area is typically flat with fine scaling. Some ringworm infections develop vesicles (fluid-filled blisters) caused by the immune system's exaggerated response to the infection.

Ringworm can look different on certain parts of the body. Athlete's foot, for example, usually causes an itchy, patchy rash with cracking (fissuring) and scaling between the toes.

Ringworm on the scalp (tinea capitis) may cause patches of hair loss with black dots on the scalp where hairs have broken off. There may also be boggy, thickened skin and tiny oozing sores on the scalp called kerions.

Signs of Ringworm on Light Skin Tones

On lighter skin tones, ringworm will cause a red, scaly patch. This makes it more easily recognized as you will see a clear demarcation between the inflamed, raised "ring" and the normal or generally lighter interior.

Because the redness (called erythema) on lighter skin is more pronounced, healthcare providers are better able to assess the severity of the infection by looks alone.

Signs of Ringworm on African-American and Dark Skin Tones

Ringworm can be harder to identify the darker your skin tone is. With African-American skin and other dark skin complexions, the rash will often look brown or ashen grey. If your skin tone is especially dark, there may be little contrast between the infected skin and normal skin.

Because of this, ringworm may go unnoticed or be confused with other conditions like an insect bite or a local skin allergy.

Even if a healthcare provider is able to identify the rash, the less inflamed appearance may lead them to minimize and undertreat the condition.

A 2022 study found that medical students at Wayne State University School of Medicine in Detroit reported only "moderate confidence" in diagnosing skin diseases like ringworm on darker skin tones. Part of the issue is that over 90% of the medical school curriculum involves images of skin diseases on light skin only.

What Causes Ringworm?

Approximately 40 different species of fungi can cause ringworm, according to the CDC. The scientific names for these fungi are Trichophyton, Microsporum, and Epidermophyton.

These dermatophytes survive on dead keratin, a protein in the top layer of the epidermis. Keratin also is found in the hair and nails, which is why the toes, feet, and scalp are so susceptible to fungal infections.

Possible Complications

If left untreated, ringworm can lead to rare but potentially severe complications, particularly in severely immunocompromised people. These include:

• Chronic dermatophytosis (persistent ringworm involving at least four body sites)
• Secondary bacterial skin infection (where breaks in skin allow bacteria to enter)
• Disseminated mycosis (spread of a local fungal infection into the bloodstream)
• Fungal pneumonia (caused when the fungal infection spreads to the lungs)
• Sepsis (a potentially life-threatening immune reaction to a disseminated infection)

How Ringworm Is Diagnosed

Ringworm infection is pretty self-apparent, given its unmistakable appearance. However, ringworm can sometimes mimic other skin conditions, including granuloma annulare, eczema, and tinea versicolor. The same can be said for infections of the scalp, which are often hard to distinguish from psoriasis or seborrheic dermatitis.

Most dermatologists can diagnose ringworm simply by looking at it. If there is any doubt, a simple, in-office test scale KOH test can provide definitive proof. This test involves taking a scraping of affected skin and looking at it under a microscope applying potassium hydroxide (KOH). The chemical breaks down everything but the fungus, making it easier to identify.

Sometimes, a dermatologist will use a special light called a Wood's lamp to diagnose a fungal infection. When illuminated by the ultraviolet light, the fungus will look blue-green.

Ringworm Doctor Discussion Guide

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How Ringworm Is Treated

Ringworm doesn't always go away on its own and should be treated. There are numerous approaches to treating ringworm infections, depending in large part on the region of the body affected.

Treatments include:

• Over-the-counter (OTC) and prescription topical antifungal creams or ointments applied directly to fungal lesions
• Antifungal shampoos used to treat infections of the scalp
• Oral antifungals for fungal infections that are resistant to topical treatments

There are also a few natural approaches for treating ringworm that have shown promise in studies, including tea tree oil for athlete's foot and garlic extract.

Prognosis

Fungal infections of the skin can be itchy and uncomfortable and even cause unsightly lesions. Tinea on the head can result in bald patches. When a fungus gets hold of fingernails or toenails, not even a manicure or pedicure may be able to mask the problem.

On the other hand, fungal infections almost always are easy to treat, and there are many effective steps you can take to prevent them based on common sense and good hygiene.

If you, your child, or a pet bring home a fungal infection, prompt diagnosis and treatment can protect the rest of the family from infection. You should also wash your hands with soap and water after playing with a cat or dog you don't know.

Summary

Ringworm (tinea) is a common fungal skin infection that causes a ring-shaped rash. It is passed from touching ringworm on someone else or coming into contact with an object contaminated with the fungal spores. The rash can look red and inflamed on light skin; on dark skin tones, the rash may be brown or grey and easier to miss.

Ringworm can often be diagnosed by its appearance alone, but a KOH test and Wood's lamp can help confirm the diagnosis if there is any doubt. The treatment of ringworm may involve topical antifungal creams or shampoos, while severe cases may require a course of oral antifungals.