Nummular eczema is a chronic skin condition that causes coin-shaped patches of an itchy rash. This condition is also called nummular eczematous dermatitis, discoid eczema, and nummular dermatitis. In most cases, the cause of this condition is unknown. Nummular eczema is sometimes caused by an allergic reaction to medication. Some doctors think that it is caused by a bacterial infection that has made the skin hypersensitive and prone to allergic reactions.

Though nummular eczema may be treated and clear up, the person is susceptible to future outbreaks of this chronic skin condition. Rashes caused by nummular eczema may start as patches of tiny red dots and small blister-like sores. The itchy rash patches may clear in the center. When the coin-shaped patches have a clear center, they can be mistaken for psoriasis or ringworm.

People prone to outbreaks of nummular eczema should avoid wool, harsh soaps, and bathing more frequently than daily, especially with hot water. Those things can cause dry, irritated skin which could trigger an outbreak of nummular eczema. Nummular eczematous dermatitis is often worse during the winter months. Low humidity and dry skin seem to make outbreaks of nummular eczema more likely.

Like other types of eczema, there is no cure for nummular eczema. Future outbreaks may be able to be suppressed with prompt treatment of cortisone cream at the first sign of an outbreak. When someone gets future nummular eczema rashes, the rashes tend to occur in the same area as previous rashes. Prescription strength cortisone cream is the preferred treatment for nummular eczema.

Special care should be taken when using prescription strength cortisone ointment. Though prescription strength cortisone cream is the best treatment for nummular eczema, it should only be applied once a day unless a doctor prescribes more frequent use. Cortisone cream of this strength should not be used on the groin, the armpits, face, or rectal area. Coal tar may be added to the cortisone cream for outbreaks that have been resistant to treatment.

Oral or injected cortisone, ultraviolet light treatments, and oral antibiotics may be part of the nummular eczema treatment. The antibiotics help fight any infection from developing since the rash can be susceptible to infection. Nummular eczema treatment includes keeping the rash moisturized. After bathing and periodically throughout the day, the person should apply Vasoline or moisturizer. Some dermatologists recommend the use of shortening, as in the fat substance used in cooking, after bathing. Vasoline and shortening can be exceptionally greasy, but they lock in moisture.