What is Nummular Dermatitis?

Itchy skin and rashes are no fun, especially when the impulse to scratch is so strong you can't sleep at night. One type of skin condition that can do this is nummular dermatitis. Like other types of dermatitis, nummular dermatitis is an inflammatory skin disease that causes itching and a rash - and it's a frustrating condition to treat.

Nummular Dermatitis Symptoms

Like other forms of dermatitis where the skin become inflamed, the rash of nummular dermatitis is intensely itchy - and it crusts and scales. One of the most distinctive features of nummular dermatitis is the characteristic coin-shaped rash that's most common on the legs and buttocks. These coin-shaped "bumps" often leak clear fluid and form a crusty covering that flakes off.

What Causes Nummular Dermatitis?

No one knows what triggers the inflammation that brings on nummular dermatitis, although dry air and lack of moisture exacerbate the symptoms in many people. Nummular eczema affects both the young and the old, but it's more common in middle-aged people, especially men, and may be linked with stress. Not surprisingly, the symptoms are aggravated by cold, dry air, so they usually peak in the winter and improve somewhat in the summer.

What Helps the Symptoms of Nummular Dermatitis?

Nummular eczema is a challenging skin condition to deal with. In mild cases, doctors recommend emollients to moisturize the skin and antihistamines to relieve the itching. In some cases, the rash becomes secondarily infected with bacteria and when it does it may respond to antibiotic treatment. If the rash is "weeping", a doctor can swab the area and see if there are bacteria involved.

One treatment with some potential is ultraviolet light therapy. U.V. light relieves the symptoms of nummular dermatitis by reducing inflammation. It may be expensive, because three to four treatments weekly are usually needed for several weeks to get sustained improvement.

Because nummular dermatitis is linked with stress, some people benefit from stress reduction techniques such as meditation, yoga, hypnosis or biofeedback. It's also important to avoid irritating or injuring the skin since this can make nummular dermatitis symptoms worse.

The Bottom Line?

If you think you have nummular dermatitis, see a doctor for a diagnosis. The coin-shaped rash of nummular dermatitis can be hard to distinguish from a ringworm infection - which requires different treatment.

References:European Handbook of Dermatological Treatments. Andreas D. Katsambas, Torello M. Lotti. Second edition.
Merck Manual. Eighteenth edition. 2006.