ConditionSkin, hair & nails
Nummular Eczema (Discoid Eczema)
Nummular eczema is a type of eczema that causes round or oval, coin-shaped patches of itchy, inflamed skin, usually on the lower legs, arms, hands and trunk. The patches may ooze and crust, then become dry and scaly. It is most common in older adults with dry skin, and can also follow skin injury or occur with other eczema. It is often mistaken for ringworm. Treatment with strong steroid creams, thick moisturizers and avoiding dry skin usually controls it, though it can come back.
Also called: Discoid eczema, nummular dermatitis, discoid dermatitis
At a glance
- What it is
- Itchy, coin-shaped patches of eczema.
- Where
- Lower legs, forearms, backs of hands, trunk.
- Who gets it
- Most often men aged 50 to 70; also young women and people with atopic dermatitis.
- Triggers
- Dry skin, cold dry weather, skin injury, irritants, poor circulation in the legs.
- Treatment
- Potent topical steroids, emollients, antiseptics or antibiotics for infected patches; light therapy for severe cases.
When to get help
See a doctor within a day or two
- Patches that become very painful, swollen, crusted with yellow crusts or pus, or with fever (possible infection)
- A rapidly spreading rash with blistering
Book a routine appointment
- Coin-shaped patches that keep spreading or do not improve after 2 weeks of moisturizers
- Patches that keep coming back in the same places
- Itch that disturbs sleep
Usually safe to manage at home
- One or two dry, itchy patches that improve with regular thick moisturizer and gentle skin care
What nummular eczema looks like
- round or oval patches 1 to 10 cm (half an inch to 4 inches) across
- well-defined edges
- early patches made of tiny bumps and blisters that ooze and crust
- later patches dry, scaly and thickened
- intense itching, especially at night; sometimes burning
- patches may clear in the center and look like rings
- skin between patches often dry
It typically starts on the legs in older adults and on the arms and hands in younger people.
Nummular eczema vs ringworm and psoriasis
| Nummular eczema | Ringworm | Psoriasis | |
|---|---|---|---|
| Edge | Uniform across the patch | Raised, scaly ring with clearer center | Sharp, thick, silvery scale |
| Oozing | Common early | Rare | Rare |
| Itch | Intense | Mild to moderate | Mild to moderate |
| Number | Several patches | One to a few, may spread | Often elbows, knees, scalp |
| Response to antifungal | No | Yes | No |
A skin scraping can tell eczema from fungal infection. Applying steroid cream to ringworm can make it worse, so check if unsure.
Causes and triggers
The exact cause is unknown. Common contributing factors:
- dry skin (xerosis), especially in winter and in older people
- skin injury: insect bites, scrapes, burns, which may trigger patches at that spot
- irritants and allergens: soaps, wool, metals such as nickel, fragrances
- poor circulation and swelling in the legs (stasis dermatitis)
- atopic dermatitis in younger people
- bacterial colonization: Staphylococcus aureus on the patches can worsen inflammation
- alcohol use and smoking
- some medicines, including isotretinoin and interferon
Diagnosis
Diagnosis is usually based on appearance. A doctor may do:
- skin scraping to rule out fungal infection
- swab for bacteria if crusted or weeping
- patch testing if contact allergy is suspected
- biopsy in unusual or unresponsive cases
Treatment
Skin care
- apply a thick, fragrance-free cream or ointment at least twice a day and after bathing
- take short, lukewarm showers or baths and use soap-free cleansers
- pat skin dry, then moisturize within 3 minutes
- use a humidifier in dry weather
- wear soft cotton clothing; avoid wool
- keep nails short and avoid scratching
Medical treatment
- Potent topical steroids applied to the patches once or twice daily for 2 to 4 weeks, sometimes under wet wraps or covered for better absorption. Nummular eczema often needs stronger steroids than other eczema.
- Topical calcineurin inhibitors (tacrolimus, pimecrolimus) for maintenance or sensitive areas.
- Antiseptic washes or antibiotic creams or tablets if patches are infected or crusted.
- Antihistamines at night to help sleep.
- Phototherapy (UVB) for widespread or stubborn disease.
- Systemic treatments such as methotrexate or dupilumab in severe, persistent cases.
Outlook
Nummular eczema can be persistent and often recurs, especially in the same spots and in winter. With consistent moisturizing and early treatment of flares, most people can keep it under control.
Frequently asked questions
What causes nummular eczema?
The exact cause is unknown, but very dry skin, cold weather, skin injuries, irritants, poor circulation in the legs and bacterial colonization often trigger it. It is not contagious.
Is nummular eczema contagious?
No. Nummular eczema cannot be passed to others. However, scratched or open patches can become infected with bacteria, which may need treatment.
How do I tell nummular eczema from ringworm?
Ringworm usually has a raised, scaly ring with a clearer center and responds to antifungal creams. Nummular eczema patches are uniformly inflamed, often ooze early, itch intensely and do not respond to antifungals. A skin scraping can confirm.
How long does nummular eczema last?
Patches often take weeks to months to clear with treatment and may return, especially in winter. Keeping skin well moisturized and treating flares early shortens episodes.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Nummular dermatitis: diagnosis and treatment
- National Eczema Association: Nummular eczema
- DermNet: Discoid eczema
- NHS: Discoid eczema
- British Association of Dermatologists: Discoid eczema