Ringworm and nummular eczema both cause circular rashes on your body. Nummular eczema is much more widespread and can cause more symptoms.
Nummular eczema (dermatitis) and ringworm are both skin conditions that can cause discoloration, itchiness, and other symptoms. People sometimes confuse these conditions because they can both cause circular rashes on the skin.
Knowing the difference can help ensure you pursue the correct treatment.
Learn more about the causes, risk factors, and treatments of nummular eczema and ringworm.
Though both skin conditions may cause discoloration and itchy, scaly skin, some symptoms can differ between nummular eczema and ringworm.
Nummular eczema can cause the following additional symptoms:
- dry skin all over the body
- patches on the skin that vary in color — while many are red, they can also be brown, pink, or yellow; yellow patches that are crusty may mean infection
- mild to severe itchiness — in some cases, nummular eczema might keep you up at night scratching
- burning sensations in the affected patches
Ringworm doesn’t cause as many symptoms as nummular eczema. Most notably, the condition appears as discolored rings along the skin. It’s common to have just one spot of ringworm, while nummular eczema often has multiple patches.
Ringworm is sometimes mistaken for forms of eczema and other skin conditions, like psoriasis. Unlike nummular eczema, the affected areas don’t vary in color, and the patches don’t burn and sometimes don’t even itch.
Nummular eczema and ringworm also have different causes and risk factors.
Nummular eczema
The cause of nummular eczema is unknown. It tends to develop after an injury to the skin, such as a scrape or cut. There are also several risk factors that may play a part, including:
- a history of excessive dry skin
- skin sensitivity
- cold, low-humidity environments
- a history of other forms of eczema, such as atopic dermatitis
- age and gender
- certain prescription acne medications
- bacterial skin infections
Though it can occur at any age, nummular eczema is most common in men over 50 years, according to the American Academy of Dermatology. Women are at higher risk in their teens and young adult years.
Ringworm
Despite the name, ringworm isn’t caused by worms. It’s caused by a fungal infection. The condition is also called tinea corporis.
This type of fungal infection
You can get ringworm from infected animals, especially cats. You may also get it from gardening in soil that has the fungus. There isn’t always a way to identify the fungus until you’ve been exposed and started having symptoms.
Ringworm can occur in people of all ages. Children may be at higher risk because of accidental poor hygiene choices, and people who spend a lot of time in gyms and public swimming areas may also be at higher risk.
You’ll need to see a doctor for a diagnosis of either condition.
It’s best to have nummular eczema diagnosed by a dermatologist. A doctor specializing in skin conditions (dermatologist) or even a primary care doctor can help determine a treatment plan and rule out other conditions.
Nummular eczema is diagnosed with a physical exam. A doctor can usually
- legs
- feet
- hands
- arms
- torso
If you have open sores within any of the rashes, a doctor may take a sample to check for an infection. This is especially important if your symptoms look like ringworm.
A sample can help them determine whether you have a staph infection caused by eczema or a fungal infection related to ringworm.
Discolored and circular rashes on the skin are a telltale sign of ringworm, but a doctor may also test a sample to confirm. They’ll look for signs of a fungal infection. If the fungal test is negative, then you don’t have ringworm.
Once you have an accurate diagnosis, a doctor can explain your treatment options.
Nummular eczema
Treating nummular eczema depends on the severity of the condition. Lifestyle measures are sometimes enough to help clear the skin. The following tips can often help:
- Avoid chemicals and metals if your condition is caused by a sensitivity to them.
- Stay hydrated to help clear up skin patches while preventing new ones.
- Bathe only in lukewarm water. A few minutes later, apply a fragrance-free moisturizer.
- If you live in a dry climate or run the heater in your home less often, use a humidifier in your bedroom.
- Wear loose cotton clothing to reduce skin irritation.
If your symptoms are severe, lifestyle measures may not be enough to clear up this type of eczema. One or more of the following medical treatments may be needed:
- antibiotics for skin infections
- antihistamines to combat itching, which may also help you sleep better at night
- prescription corticosteroid ointments to reduce swelling or inflammation
- oral or injectable corticosteroids
- medicated bandages
- phototherapy or light treatment
Ringworm
Ringworm may be treated with different types of antifungals, particularly if it affects the scalp. Oral antifungals, such as griseofulvin (Grifulvin V, Gris-Peg), may be taken by mouth. A doctor may also prescribe topical antifungal ointments.
Some antifungal ointments are also available over the counter, such as those containing the active ingredients ketoconazole and clotrimazole. These include Lotrimin AF, Cruex, and Desenex. These are usually sufficient for
Ringworm shouldn’t be treated with topical corticosteroids (as nummular eczema is) as these can make ringworm worse.
Ringworm may also be managed and prevented through changes to your personal hygiene routine. The following habits can be helpful:
- Shampoo and bathe every day.
- Wear shoes or sandals in public places, including locker rooms and public pool areas.
- Change clothing every day, including socks.
- Avoid sharing hats and hygiene tools such as loofahs and combs.
Nummular eczema may take longer to treat than ringworm does. It may clear up within a year, though there’s a risk that it could return.
Patches and sores on the lower body can take longer to clear up, and some people experience scarring. Compared to other forms of eczema, nummular eczema doesn’t cause lasting issues for many people.
For ringworm, most people see improvements after just a few days of treatment. Ringworm isn’t usually a recurring problem, but it may come back if you don’t make changes in personal hygiene.
How can I tell the difference between eczema and fungus?
You can tell the difference between eczema and fungus by paying attention to the most prominent symptoms. Eczema typically presents as a flat rash, whereas a fungal infection causes raised areas of the skin.
Why do I suddenly have nummular eczema?
You may suddenly have nummular eczema due to several factors, such as an insect bite, dry skin, a chemical burn, or trauma to the skin.
What mimics nummular eczema?
Ringworm can sometimes mimic nummular eczema, as the two skin conditions share multiple symptoms. However, nummular eczema is much more widespread.
Ringworm and nummular eczema can both result in circular rashes on the body. However, nummular eczema can be much more widespread and cause more symptoms, such as multiple discolored patches and burning sensations.
A dermatologist can help diagnose the skin condition by performing a skin analysis. If you have any open sores, they may take a sample to check for an infection and for ringworm.