What Triggers Nummular Eczema?

Medically Reviewed on 10/28/2022
nummular eczema
Medication, phototherapy, and home treatments are treatment options for nummular dermatitis.

Although the precise etiology of nummular eczema is unknown and there are no established medical causes, researchers believe that sensitivity of the skin to weather and harsh chemicals may play a significant role in triggering nummular eczema.

12 common risk factors or triggers for nummular eczema

Twelve common risk factors or triggers for nummular eczema include:

  1. Having a family history of allergies or atopic dermatitis (asthma or hay fever)
  2. Dry skin
  3. Previous damage to the skin due to scrapes, scratches, chemical burns, or even insect bites
  4. A cold, dry climate
  5. Having circulation problems in your legs
  6. Prone to bacterial skin infections
  7. Taking certain medications or a side effect of medications used for treating hepatitis C, arthritis, or other skin allergies. Topical medications such as neomycin.
  8. Having another type of eczema
  9. Exposed to certain irritants, such as metals or soaps (metals such as nickel and chemicals such as formaldehyde)
  10. Stress
  11. Exposed to sudden temperature change
  12. Rough clothing

Nummular eczema is more frequent in men who generally have their first breakout between the ages of 55-65 years. Women who have it are more likely to develop it between the ages of 15-25 years.

What is nummular eczema?

Discoid eczema, also known as discoid dermatitis, nummular dermatitis, or nummular eczema, is a chronic skin inflammation that is both painful and irritating.

  • Although discoid eczema is not infectious, it can be chronic, recurring, and long-lasting.
  • The plaques do not form on the face or scalp, but they can be found in many regions of the body.
  • These patches can range in size from a few millimeters to a few centimeters.

11 signs and symptoms of nummular eczema

Eleven signs and symptoms of nummular eczema include the following:

  1. Growth of coin-shaped lesions (in patches) over the body
  2. Red spots or lumps on the skin that gradually merge together to create bigger pink, reddish-brown patches that can range in size from a few millimeters to several centimeters
  3. Lesions are most usually observed on the arms or legs although they can progress to the chest and hands; lesions might be brown, pink, or red depending on the individual's skin tone
  4. Blisters around the patch along with oozing out pus
  5. Inflammation and itching around the patch
  6. Skin discoloration might develop when the spot flattens; this darkening is known as post-inflammatory hypopigmentation in dark skin and can last for several months
  7. Instead of a coin-shaped lesion, a new flare-up may appear as a huge, elevated patch on top of an existing, healing location
  8. Fatigue
  9. Fever
  10. Shivering
  11. Generalized feeling of being unhealthy


Eczema (also atopic eczema or atopic dermatitis) is a general medical term for many types of skin inflammation. See Answer

5 common locations of nummular eczema on the body

Discoid eczema can form anywhere on the body. However, it is less common on the face or scalp. It is most frequent on the following parts of the body:

  1. Lower legs
  2. Forearms
  3. Trunk (the body, excluding the head, neck, and limbs)
  4. Hands
  5. Feet

If you cure your discoid eczema and it recurs, the patches may appear in the same location as previous lesions.

3 types of nummular dermatitis

Nummular dermatitis is clinically divided into these three types:

  1. Exudative (wet) nummular dermatitis:
    • Exudative nummular dermatitis can be acute or chronic, lasting weeks, months, or, in rare cases, years.
    • This type of nummular dermatitis can develop at any age. However, it is most frequent in people older than 50 years. It is more prevalent in men than in women.
  2. Dry nummular dermatitis:
    • Dry nummular dermatitis can be localized or widespread (affect multiple areas of skin).
    • This type of nummular dermatitis is frequently caused by dry skin, which can be caused by the predisposition to develop allergic illnesses, excessive bathing with soap and water, or as a side effect of using oral retinoids.
    • Dry nummular dermatitis can create raised skin lesions such as Meyerson's nevus (moles) and seborrheic keratoses (common, noncancerous skin growths that arise after the age of 30 years).
  3. Autosensitization dermatitis:
    • Nummular dermatitis arises as a result of severe dermatitis elsewhere. This is referred to as an interface dermatitis response (an itchy form of dermatitis usually distantly associated with another inflammatory or infectious skin lesion).
    • The trunk and limbs are affected by autosensitization dermatitis, with the lower legs being the most common main location due to stasis dermatitis. It may be rather comprehensive.

How do doctors diagnose nummular eczema?

Dermatologists frequently diagnose nummular dermatitis by examining the person’s skin.

  • If the dermatologist suspects a skin infection, they may take swabs from the lesions during the exam.
  • Patch testing (skin tests to detect allergies) may be recommended if your dermatologist believes you have an allergy.
  • If therapy does not completely clean your skin, your dermatologist may prescribe patch testing.

What is the treatment for nummular eczema?

Medication, phototherapy, and home treatments are treatment options for nummular dermatitis. Because the symptoms of nummular dermatitis can be persistent and long-lasting, it is essential to contact a doctor for proper therapy.

Medication for nummular dermatitis

  • Steroids
    • Steroids can be used topically, orally, or intravenously.
    • Topical steroids are anti-inflammatory lotions and ointments that are used one or two times a day in the afflicted regions for two to four weeks.
    • Stronger steroids may be required for this persistent form of eczema. However, stronger steroid creams will thin the skin over time.
    • Oral steroids are systemic and should only be used in severe cases of nummular dermatitis. They provide rapid but temporary relief.
    • Steroids can be injected into extremely recalcitrant regions of nummular dermatitis.
  • Oral antihistamines
    • To reduce the itching caused by nummular dermatitis, your doctor may prescribe antihistamine tablets or recommend over-the-counter antihistamines. 
    • These are very useful for resting at night.
  • Antibiotics
  • Immunosuppressants
    • Occasionally, persistent and more severe nummular dermatitis may be treated with immunosuppressant medications. 
    • These may be more effective and safer than long-term systemic steroids. 
    • Careful monitoring of blood work and side effects by a dermatologist is required for these treatments.


  • Phototherapy can be used to treat generalized or extensive nummular dermatitis (also called light therapy).
  • This method relieves irritation and rash. It works by exposing the damaged skin to natural sunshine, ultraviolet A or UVB rays.

Home care tips

  • Protect your skin from injury and trauma
  • Take short baths
  • Moisturize and apply emollients as and when needed
  • Avoid skin irritants
  • Follow your doctor’s instructions
  • Join a support group

Nummular dermatitis can be resolved with adequate therapy. Sores on the thighs, legs, and feet sometimes take longer to heal and leave behind darker or brighter areas. 

Some individuals' skin clears up within a year. Others have had these patches for many years. Patches appear and then disappear. Patches that reappear after clearance tend to occur in the same location as the first outbreak.

Medically Reviewed on 10/28/2022
Image Source: iStock image

"Nummular Eczema." American Osteopathic College of Dermatology. <https://www.aocd.org/page/NummularEczema>.

"Nummular Eczema." National Eczema Association. <https://nationaleczema.org/eczema/types-of-eczema/nummular-eczema/#:>.