At first glance, it can be tricky to tell nummular eczema and ringworm apart. After all, both skin conditions cause round, discolored, itchy rashes.

Despite their similarities, several key differences can help you distinguish nummular eczema from ringworm. This article compares the two skin conditions, including differences in their symptoms, causes, and treatment options.

5 Differences in Symptoms

Nummular eczema and ringworm (also called tinea corporis) have similar symptoms but are very different skin conditions.

Nummular eczema (also called nummular dermatitis or discoid eczema) is a chronic (long-lasting) condition caused by dry skin, other types of eczema, or trauma to the skin. This condition isn’t contagious, so you can’t spread it to others.

Ringworm, on the other hand, is a contagious skin infection caused by fungi — it’s not related to worms of any kind. With the use of oral or topical antifungal medications, ringworm often clears up in two to four weeks.

Both conditions cause discolored round patches on the skin called plaques, so it’s easy to confuse nummular eczema and ringworm. This article describes five key differences between the two conditions.

1. Ringworm Plaques May Have a Clear Center

Plaques from nummular eczema usually look like scaly, itchy coins that are red, purple, dark brown, or ashen, depending on your skin tone. A plaque’s border and center are usually the same color.

Ringworm typically involves red, purplish, brown, or gray bumps, as well as clearer skin, within a “ring” that gives the condition its name.

2. You’ll Usually See Multiple Nummular Eczema Plaques

Nummular eczema plaques typically range in size from three-quarters of an inch to 4 inches across. Although you might see just one nummular eczema plaque, they tend to strike in groups.

Ringworm, however, usually appears as just one or two patches.

3. Nummular Eczema Symptoms May Come and Go

There’s no cure for nummular eczema. Symptoms may subside with treatment but flare up later. The symptoms may come and go throughout your life.

Ringworm, however, isn’t a chronic condition. The infection can be cured using antifungal treatments and shouldn’t return after it clears.

4. Nummular Eczema Plaques Tend To Affect Arms and Legs

Although ringworm may appear anywhere on your body, nummular eczema is more likely to affect the arms, legs, hands, and torso than other areas. Location isn’t a definite indicator of ringworm versus eczema, but it may help guide you when considered along with other symptoms.

5. Nummular Eczema Plaques May Be Wet

Ringworm patches are usually dry and may crack. Nummular eczema can also be dry but is sometimes exudative (wet and oozing) and may involve small blisters.

How Can You Tell the Difference Between Nummular Eczema and Ringworm?

The plaques that form with these conditions may look similar. Some MyEczemaTeam members have described seeing eczema that looks like ringworm. However, these conditions have distinct differences that a primary care doctor or dermatologist can spot.

What Causes Nummular Eczema and Ringworm?

Ringworm and nummular eczema have different causes. In addition, a person could have ringworm and nummular eczema at the same time.

Ringworm

Ringworm is caused by fungi called dermatophytes. This contagious condition can be picked up from another person, an animal (like a household pet), or an object (by touching a surface contaminated with the fungus). Rarely, ringworm can be spread through soil infected with dermatophytes.

Nummular Eczema

Nummular eczema isn’t contagious and has no known single cause. This condition can affect anyone of any age, but it’s slightly more common in females ages 15 to 25 and males ages 50 to 65, according to StatPearls, an online health care resource.

Certain triggers may make it seem like you suddenly have nummular eczema. Always contact a dermatologist or other health care provider if you notice new, surprising skin symptoms.

Dry Skin

Like other forms of eczema, nummular dermatitis is often attributed to triggers such as dry skin. Having particularly dry skin can weaken a person’s first physical barrier — the skin — against irritating substances and chemicals. As a result, contact with otherwise harmless substances may cause irritation and itchiness. Using a moisturizer daily can help relieve dry skin and restore your skin barrier.

Contact Dermatitis

Contact dermatitis is a type of eczema that occurs when your skin comes into contact with irritants or allergens. Nummular dermatitis can sometimes be caused by allergic or irritant contact dermatitis, with common triggers including metals such as nickel, mercury, and gold. If you suspect you have a contact allergy, talk to your dermatologist about allergy testing called patch testing, which can help identify specific allergens.

Atopic Dermatitis

Some people with nummular dermatitis also have a history of atopic dermatitis, a chronic type of eczema that often develops in the first six months of life. Typically, atopic dermatitis appears as a dry, scaly, itchy rash that can be pink, red, purple, or dark brown, depending on skin tone.

Certain Medications

Drug-induced nummular dermatitis occurs when certain medications weaken the skin’s immune response or affect the outer layer of the skin, making it more susceptible to irritation and inflammation. Medications that can induce nummular dermatitis include:

• Diuretics to treat high blood pressure, kidney stones, and more
• Statins, which are cholesterol-lowering drugs
• Immune-modulating medications for treating hepatitis C, such as ribavirin and interferon
• Tumor necrosis factor inhibitors, which are used treat arthritis and other conditions
• Intravenous immunoglobulin, a treatment for immune deficiency

Skin Injury

In some cases, trauma to the skin — such as an injury, a burn, or a bugbite — may trigger nummular dermatitis.

How Are Nummular Eczema and Ringworm Diagnosed?

Both nummular eczema and ringworm can be diagnosed through a skin examination by your primary care provider or a dermatologist. Because the two conditions look similar, it’s better to have a doctor examine your skin rather than to self-diagnose. Your health care team can determine the cause of your symptoms and prescribe the right treatment.

Your doctor might swab or scrape your rash to get a small skin sample, which can be looked at under a microscope to help diagnose nummular eczema or ringworm.

Skin Swab

A long cotton swab can be brushed over the affected area and examined for signs of eczema or for dermatophytes. The presence of dermatophytes may indicate ringworm.

Skin Scraping

For skin scraping, a doctor uses a small razor to gently remove flakes of skin from the rash for examination. This procedure is similar to shaving body hair and doesn’t hurt.

Fungal Culture

A fungal culture involves sending the swab or scraping to a lab to check for ringworm.

How Are Nummular Eczema and Ringworm Treated?

Nummular eczema and ringworm call for different treatments. With nummular eczema, treatment focuses on both preventing symptoms and treating flare-ups when symptoms of this chronic condition do occur. Ringworm, on the other hand, can be treated with medications and usually clears up in two to four weeks.

Treatments for Nummular Eczema

Managing nummular eczema often begins with prevention. Strategies include:

• Wearing clothing made from soft, natural fabrics, such as cotton
• Using gentle, fragrance-free soaps and detergents
• Applying fragrance-free lotions or ointments to keep skin hydrated
• Running a humidifier to keep your home or bedroom cool and moist

For nummular eczema flare-ups, treatment typically includes medication and phototherapy (light therapy).

Medications

Prescription or over-the-counter medications to treat nummular eczema may include corticosteroids, which can be topical (applied to the skin) or oral (taken by mouth). Corticosteroids help reduce inflammation throughout the body. Although steroid creams are most commonly used, steroid-free options such as the following may be substituted:

• Crisaborole (Eucrisa)
• Pimecrolimus (Elidel)
• Tacrolimus (Protopic)

Coal tar cream may help manage nummular eczema by reducing inflammation, scaling, and itching. This treatment also works by slowing down the fast turnover of skin cells, which can make eczema symptoms worse.

Treatment may include antihistamines, which help relieve itching and other allergy symptoms. Antibiotics may be used, especially if the plaques become infected. Other oral medications may also be used for persistent symptoms of nummular eczema.

Phototherapy

In phototherapy, a machine produces ultraviolet A or B rays, which are similar to natural sunlight. The device is used on your skin for seconds or minutes over a series of sessions.

Treatments for Ringworm

The most common treatments for ringworm are antifungal medications in the form of creams, ointments, shampoos, or pills. Topical creams containing clotrimazole, miconazole, and terbinafine are commonly used. An extensive ringworm rash might be treated with oral antifungals such as fluconazole or terbinafine.

During treatment, it’s important to prevent ringworm from spreading to others. Take precautions such as these:

• Don’t share personal care items such as towels, razors, soap, and body lotion.
• Launder and dry all clothing, bedding, and linens using high heat.
• Wash your hands after touching any ringworm plaques, especially if the infection came from a pet.
• Remove wet or sweaty clothing as soon as possible.
• Shower or bathe regularly.

Be sure to finish all medications as prescribed, even if your symptoms improve. If you have side effects or questions about the medications, talk with your doctor.

Find Your Team

On MyEczemaTeam, the social network and online support group for people living with various types of eczema, more than 53,000 members come together to ask questions, give advice, and share their experiences living with eczema.

Have you ever had nummular eczema or ringworm? Did you find it difficult to tell the two apart? Share your experience in the comments below or by posting on your Activities page.