Nummular Eczema vs Ringworm: Symptoms, Causes, and Treatments

Introduction

Discovering new and uncomfortable symptoms on your skin can be distressing. Especially when you’re unsure of the underlying cause.

Circular or oval-shaped lesions on the skin that feel red, chapped, irritated, and itchy can be a sign of nummular eczema or ringworm. These separate skin conditions are often confused for one another, but they require different treatments in order to resolve symptoms.

This article will help you understand more about the similarities and differences between nummular eczema and ringworm, including their symptoms, causes and recommended treatment strategies. 

What Is Nummular Eczema?

Nummular eczema causes scattered, circular patches on the skin. These coin-like patches are usually very itchy. They can also ooze and feel dry or sensitive. 

Nummular eczema is also referred to by two other names: 

• Discoid eczema.
• Nummular dermatitis.

Anyone can get nummular eczema, but it tends to affect men more than women and appear most often in middle-aged adults. 

Experts aren’t sure what causes nummular eczema, but some known triggers include:

• Very dry or sensitive skin.
• Bathing frequently in hot water.
• Living in an environment with low humidity.
• Insect bites.
• Scrapes.
• Chemical burns.
• Poor blood flow (when lesions appear on the legs). 
• Exposure to rough fabrics, like wool. 
• Allergic reactions such as contact dermatitis to metals, like nickel.
• Certain medications (including antivirals, retinoids, and isotretinoin). 

Symptoms

The hallmark symptom of nummular eczema is the coin-shaped lesions that can appear on the arms, legs, torso, and hands. 

In fact, the shape of these patches inspired its name: the word “nummular” derives from the Latin for “coin.”

These patches can vary in size, from dime-sized to roughly the size of a half-dollar coin. Their edges usually look fuzzy or inflamed. 

Additional symptoms of nummular eczema may include:

• Itching and burning.
• Patches that ooze liquid. 
• Patches that crust over.
• Red, pink, or brown skin surrounding the lesion.
• Scaliness and inflamed skin.

Treatment

Once correctly identified, nummular eczema can go away completely with the right treatment. However, they may leave temporary discolored patches on the skin.

Usually, there are several steps to treating nummular eczema: 

1. Application of a mid-to-high potency topical corticosteroid. When possible, apply the medication to damp skin immediately after bathing.
2. Application of a topical antibiotic, as nummular eczema patches can be infected with Staphylococcus aureus (staph).
3. If your nummular eczema patches ooze liquid or form a yellow crust, this may be a sign of infection or excessive inflammation. In that case, it’s best to seek a consultation with a dermatology expert who can recommend the right treatment plan according to your symptoms.

If your patches are widespread, you may need stronger treatment, like a localized injection of corticosteroids.  

Narrowband UVB (NB-UVB) phototherapy, a type of light treatment, may also help manage nummular eczema. To explore phototherapy options near you, visit Phothera’s provider directory for in-person and virtual care options.

Management and Prevention 

Managing nummular eczema involves strategies that help restore the natural skin barrier and avoiding behaviors that can trigger dry and irritated skin and cause future flare-ups. 

Here are the strategies dermatologists recommend for managing and preventing nummular eczema:

• Frequent moisturization with a moisturizer that contains thick emollients, which are types of ingredients that soothe skin and keep it moisturized. One randomized-controlled study also suggests that moisturizers with ceramides are effective at reducing water loss in the skin.
• Take short lukewarm showers and use gentle, hydrating soaps. Moisturize skin immediately after exiting the shower and while your skin is still slightly wet.
• If the itchiness from your nummular eczema is affecting your quality of life, including preventing you from sleeping, there are some psychotherapeutic interventions, like mindfulness, that can help. 
• Sleep with a humidifier in the room. 
• Avoid tight clothing and irritating fabrics.

What Is Ringworm?

Though its name might suggest otherwise, ringworm is a fungal infection. The three most common fungi that cause ringworm are Trichophyton rubrum, T. tonsurans, and Microsporum canis. 

The infection is also known as:

• Tinea.
• Dermatophytosis.

Anyone can get ringworm, but it most commonly affects post-pubertal children and young adults. 

Ringworm can affect different parts of your body, including:

• Beard (also known as tinea barbae).
• Torso (also known as tinea corporis).
• Feet (also known as tinea pedis or athlete’s foot). 
• Groin area (also known as tinea cruris or jock itch).
• Scalp (also known as tinea capitis). 
• Nails (also known as tinea unguium or onychomycosis). 

Ringworm is contagious and can easily spread through contact with people who have the infection, unwashed clothing, combs, damp surfaces (like public swimming pools or gyms), or even pets (cats are common carriers). 

Other risk factors for ringworm include:

• Playing contact sports.
• Living with diabetes.
• Living with obesity.
• Sweating heavily.
• Close contact living.
• Spending time in a humid or tropical environment.

Symptoms

Ringworm on the torso, arms and legs causes well-defined ring-like or circular patches on the skin (ringworm on the palms, feet, scalp, groin, and nails lack this distinctive pattern). 

Additional symptoms can include:

• Red, pink, brown, or gray patches on the skin.
• Itching.
• Burning.
• Cracked skin between the toes (athlete’s foot). 
• Patches that appear lighter or clearer in the center (attributing to its ring-like appearance). 

Treatment

In many cases, topical, over-the-counter antifungal creams, like miconazole or clotrimazole, will work to treat ringworm and resolve symptoms completely. 

However, if topical antifungals don’t clear the infection and/or if the lesions are extensive, oral or systemic antifungal treatment may be recommended.

Management and Prevention

Certain lifestyle habits can also help to manage and prevent ringworm, including:

• Shampooing your hair and bathing once a day.
• Wearing sandals or flip-flops in public locker rooms and swimming pool areas.
• Change clothing every day, including underwear and socks.
• Avoid sharing hats and other personal hygiene tools like hair brushes, combs, and loofahs. 

Nummular Eczema vs Ringworm

At first glance, it can be difficult to tell the difference between nummular eczema and ringworm. But these two skin conditions have different causes and different treatments, which is why getting an accurate diagnosis is crucial to understanding the next steps needed to get you feeling better. 

Cause

Ringworm is caused by a fungal infection while nummular eczema can be triggered by a variety of different factors, including an allergic reaction, skin trauma, and environmental exposure.

Diagnosis

If you’re unsure whether your symptoms are a sign of nummular eczema, ringworm, or another skin condition, it's important to see a dermatology expert for an accurate diagnosis. 

Spotting the difference between these conditions can be difficult, even for a general health practitioner without expertise in dermatology.

Depending on the presentation, your provider may recommend a potassium hydroxide (KOH) microscopy test for diagnosing ringworm or a biopsy for more complex eczema cases. 

Treatment

Nummular eczema and ringworm are treated differently, which is why it’s important to speak with a dermatology expert in order to guide the right treatment plan for your symptoms.

Nummular eczema is usually treated with a combination of a topical corticosteroid and a topical antibiotic, while ringworm is usually treated with a topical antifungal.

However, getting an accurate diagnosis remains key. Topical corticosteroids used to treat nummular eczema can worsen symptoms when applied to ringworm, so be sure to consult with a dermatology expert before starting treatment.

With ringworm, it’s also important to treat potential carriers to prevent reinfection. Some people get infected with ringworm from their cats or partner, which is why treating the original source of infection can help to stop the spread. 

Similarities and Differences

Both nummular eczema and ringworm cause circular patches on the skin that can feel itchy and irritated, which can make it difficult to distinguish between the two conditions. 

Ringworm patches typically have sharp, well-defined borders, while nummular eczema patches often have fuzzy or inflamed edges.

Sometimes, the center of a ringworm patch will be clear or lighter in color, but this isn’t always the case. 

Nummular eczema can cause more symptoms, like oozing or crusting over. Ringworm can also cause additional symptoms, like crumbling nails, depending on where the infection is located on your body. 

Because these conditions are caused by different triggers, they require different treatments. In most cases, both conditions will resolve with the right treatment.

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For top-notch dermatology care that brings relief, connect with a qualified skincare provider. Dermatology experts at Zest will help you manage your symptoms with individualized treatment plans that cater to your needs and prevent future flare ups. Better yet, book a virtual appointment within days.