Nummular Eczema Explored: How To Deal With The Condition

A 20-year-old woman in the middle of the night with intense itching; she notices a few raised, red, circular lesions on her forearm. Her GP tells her it is tinea corporis–ringworm–and prescribes an antifungal cream. The lesions do not respond to the treatment. In fact, more develop on the other arm.

After weeks of frustration, she seeks a dermatologist’s care. After the dermatologist swabs the lesions and takes a scraping, she leaves with a prescription for a corticosteroid cream and a topical antibiotic. Within a week, the itching and redness of the lesions seems to have improved; within a month or so, most of the lesions have cleared up. 

While working outside, a 55-year-old man sustains a scratch to his shin. He gives the minor injury no thought until a rash erupts around the scratch a few days later. His wife encourages him to see his doctor, who diagnoses him with impetigo and prescribes topical antibiotics. The rash spreads down his shins. 

Fearing an antibiotic-resistant strain of staph, his doctor orders a swab of the lesions. He tests positive for staphylococcus aureus, but it should have responded to the prescribed antibiotics. He refers his patient to a dermatologist, who prescribes a topical corticosteroid. 

When the steroid treatments produce only moderate improvement, the dermatologist prescribes phototherapy. The lesions resolve within weeks. 

A young man develops a rash over his arms and the backs of his hands. He already has an appointment with his internist to investigate some painful gastric symptoms, so he mentions it in passing and is given a prescription for corticosteroids. The day after his visit, the internist’s office calls to tell him that he’s tested positive for H. Pylori and is at risk of developing a gastric ulcer. They prescribe several treatments, including two different antibiotics to take concurrently. 

Over the next two weeks, the young man’s gastric issues begin to resolve. At his follow-up appointment, the H. Pylori infection has successfully resolved. The internist inquires about the rash; the young man realizes that it has resolved within the same time frame as his gastric symptoms. 

The hypothetical cases above illustrate some of the different ways in which nummular dermatitis, also known as discoid dermatitis or nummular eczema, can present and how it might be treated. 

What is Nummular Dermatitis?

Nummular dermatitis is a skin disorder characterized by round, itchy, red lesions. The disorder takes its name from the Latin word nummulus, or “coin,” as its lesions are small and round. It occurs primarily on the arms and legs, especially the fronts of the limbs, as well as on the back of the hand. It is sometimes called discoid dermatitis. 

Nummular dermatitis lesions typically begin as ill-defined patches of rough scaly red skin that soon form round, coin-shaped plaques. Ranging in size from 1 to 10 centimeters, these plaques often itch and burn and can become moist and oozing.  At this point, they are truly Nummular eczema. Eczema is an old dermatology term that refers to conditions of dermatitis that can become moist or oozing. As the flare progresses, these lesions can become more widespread on the arms, legs, and trunk.

Nummular eczema most commonly affects the legs of people who bathe with too much soapy hot water, and have forced-air heating in the winter for their home. The arms, back of the hands and trunk can become involved. It does not usually affect the scalp or the face.

Risk factors With Nummular Eczema

Some websites describe it as rare, but nummular dermatitis can develop in most people over 30 who have very low humidity in their homes, and bathe frequently with harsh soap and very hot water. It’s common in people with Atopic dermatitis, but anyone can develop nummular dermatitis. It  most often affects men over the age of 50 (oil glands no longer lubricate as well) and young women shaving their legs frequently with soap and hot water . It is rarely seen in children.

A diagnosis of atopic dermatitis or other atopic disorders (e.g., asthma, hay fever) is associated with a higher risk of acquiring nummular dermatitis. It often occurs where skin has been irritated or injured, appearing after bug bites, burns, and exposure to metals such as nickel. Poor blood flow is another risk factor, especially in the legs. 

There is a correlation between nummular dermatitis and poor vascular health. Chronic venous insufficiency (CVI), in which the veins cannot efficiently move blood back to the heart, is a predisposing factor for the disorder. 

Nummular dermatitis is also strongly associated with some internal disorders, seen often in patients with helicobacter pylori (H. pylori) infection, giardiasis, and liver disorder. Alcoholism is a predisposing factor, especially when cirrhosis of the liver is involved. 

What Causes Nummular Dermatitis?

Like other types of eczema, nummular dermatitis is a multifactorial disorder, and its etiology is not clearly understood. Among seemingly disparate risk factors, the common threads are dry skin and inflammation. 

Nummular dermatitis is almost always preceded by damage to the skin barrier and subsequent drying of the skin. Once this damage occurs, the skin is more open to irritants and allergens. 

Exposure to these irritants triggers the production of cytokines in the skin; the cytokines then act as recruiters of T Cells and other immune system cells. These immune system cells work to expel the irritant, bacterium, or allergen, and inflammation occurs. Redness, itching, and edema are indicators of this inflammation. Swelling or edema within the epidermis can lead to small blisters and oozing from the coin-shaped patches.

This immune system response is triggered further when itching causes scratching and more damage to the skin barrier. Gastric bacteria (like H. pylori) can also trigger inflammation.

Evaluation and diagnosis

Nummular dermatitis  lesions resemble those caused by many other conditions, including tinea corporis (ringworm), pityriasis rosea, plaque psoriasis, and contact dermatitis. 

The rash is sometimes misattributed to impetigo, and diagnosis can be complicated in cases where secondary impetigo has developed. It is also sometimes incorrectly diagnosed as stasis dermatitis. 

While general practitioners can diagnose and treat nummular dermatitis, a rash that fails to respond to treatments warrants a visit to a board-certified dermatologist. 

The exam usually consists of a visual examination of the skin with a dermascope. If the dermatologist sees more than one possibility for diagnosis, a skin scrape and/or a swab may be ordered. A patch test may be ordered if contact dermatitis is suspected. 

It is important to note that basal cell skin cell cancer can resemble a single lesion of nummular dermatitis. This should be ruled out by an exam with a Dermatology Provider when there is a lone persistent lesion.

Treating Nummular Dermatitis

The two primary goals of treatment are restoration of the skin barrier and interruption of inflammation. 

Restoration of the skin barrier begins with a patient’s own self-care. Skin must be moisturized frequently, using a heavy, occlusive emollient such as petroleum jelly if needed. 

Excessive bathing (more than once a day for more than 20 minutes at a time) and hot water can worsen nummular eczema; short (less than 20 minutes) lukewarm showers are best. Skin should be moisturized thoroughly after the bath, while the skin is still damp.  Harsh soaps or body washes should be exchanged for gentler products, and patients should avoid scratchy fabrics or tight clothing. 

For inflammation, the most common treatment on the web is twice-daily application of a mid to high-potency topical corticosteroids. Occasionally, systemic corticosteroids may be prescribed; this is associated with rebound symptoms, though, and is not preferable as a first-line treatment.

Sometimes, patients benefit from alternating between corticosteroid treatment and the application of topical calcineurin inhibitors (such as ElidelⓇ). For example, they may use topical steroids for five days, then switch to a calcineurin inhibitor for two. The monoclonal antibody Dupilumab (DupixentⓇ) is sometimes prescribed off-label for treating stubborn nummular eczema cases.

In cases where topical treatments are either effective or unfeasible, a dermatologist may recommend light therapy with narrowband UVB light. In rare cases, immunosuppressants may be prescribed.

Scratching lesions can lead to impetigo infection. Should this happen, patients must take antibiotics in addition to their anti-inflammation treatments. Diphenhydramine (BenadrylⓇ) and hydroxyzine (VistarilⓇ) may be prescribed to combat itching. These antihistamines also have a mild sedative effect, which is helpful if itching has interrupted sleep. 

The Prognosis for Nummular Eczema

With treatment, most cases of nummular eczema resolve within a matter of weeks. Occasionally, though, the symptoms last much longer, and relapses are not uncommon. 

Pigment changes–either lightening or darkening of affected skin–might persist after nummular eczema resolves. 

Nummular eczema flares can reoccur in a chronic, relapsing-remitting pattern for years. Each flare should be treated appropriately to hasten resolution and to prevent complications like infection.

SmartLotionⓇ: a smart choice for nummular eczema

Board-certified dermatologist Dr. Steve Harlan knows first-hand how frustrating and demoralizing conditions like nummular eczema can be for patients. The symptoms are uncomfortable and sometimes relapse and remit chronically. The most common treatment for these disorders, though, cannot be used long-term; topical corticosteroids can only be used for a few weeks at a time and can lead to atrophy and topical steroid withdrawal. 

His patients’ struggles inspired Dr. Harlan to develop a steroid cream that would relieve inflammation without the risk of skin atrophy and topical steroid withdrawal when used properly.. SmartLotionⓇ is the result of his expertise and dedication to his patients. 

Dr. Harlan formulated SmartLotionⓇ with prebiotic ingredients. This helps balance the skin’s microbiome, which helps the skin barrier repair itself.. 

Because it promotes the skin’s overall health, SmartLotionⓇ can effectively treat inflammation with a much smaller dose of hydrocortisone (0.75%) than most all other corticosteroid creams. SmartLotionⓇ therefore does not cause topical steroid withdrawal or skin atrophy, even when used as needed long-term, with a Dermatology Provider’s supervision. This is important when treating conditions like chronic nummular eczema and other chronic recurring forms of dermatitis.

There is good news. Many cases of Nummular dermatitis can be prevented from recurring simply by using the best skin barrier-repairing moisturizers. That’s why Dr. Harlan formulated

HarlanMD Perfect Repair™ moisturizing cream. 

Like SmartLotionⓇ eczema cream, Perfect Repair incorporates a Prebiotic strategy for reducing harmful bacteria and yeast in the skin. Perfect Repair™is loaded with natural ceramides, and it contains fragrance-free coconut oil for its powerful healing benefits on eczema. There really is nothing like it for healing and repairing dry, injured skin.

Treating nummular eczema with SmartLotionⓇ and Perfect Repair™ moisturizing cream

Dr. Harlan has his nummular dermatitis patients start by applying SmartLotionⓇ two to three times a day to the rash, for up to four weeks. Perfect Repair™ moisturizing cream or CeraVe® cream is applied twice daily to the affected areas, and once daily to the entire arms, legs, and hands (It’s also great for dry damaged lips).

As improvement and clearing occurs within that period, he has them taper down to one application per day of each product. SmartLotion should be applied to the sites of recurring eczema, and the Perfect Repair should be applied once daily to the entire arms and legs. 

Eventually, patients apply each product three times a week for the prevention of nummular eczema. Dr. Harlan has found this to be the fastest way to treat Nummular eczema without resorting to high-potency steroids like many websites recommend.

According to Dr. Harlan, moisturizing every other day with Perfect Repair should be a routine part of self-care, even in the absence of rashes. He says adult patients can apply SmartLotionⓇ once a day to prevent outbreaks of atopic dermatitis; some patients only require three applications a week.

Tips for nummular dermatitis patients

Like any other inflammatory skin disorder, nummular eczema is uncomfortable and demanding. Fortunately, patients can get the upper hand on this skin disorder with some supportive self-care: 

• Avoid showers or baths longer than 10 minutes, and use warm water, not hot.

• Try to avoid bathing more than once a day.

• Use soap like Basis® bar, Cetaphil® bar, or CeraVe® bar, and do not soap the outer arms and legs. Some patients may try Dial® deodorant bar for underarms and lower truncal areas.

• Use gentle products for laundry, dishes, and house cleaning

• Wear soft, loose clothing that does not chafe the skin.

• Moisturize twice a day, and apply a streaky amount of cream in only a downward

• Direction on hairy arms and legs.

• Add humidity to the house in the winter months

• Get a proper diagnosis and supervision from your Dermatology Provider.

Finally, ask your doctor about using pre-biotic 0.75% Hydrocortisone, instead of stronger steroids. Most people can safely use it along with their prescription treatments.

Steven Harlan MD

Board Certified Dermatologist

Inventor of SmartLotion®