What causes nummular dermatitis?

Medical causes of nummular dermatitis are unknown. Researchers have predicted that sensitivity, especially in the skin, may play a major role in causing this problem.

What substance (s) could the body be sensitive to?

• Metals: some people find out they grow sensitive to nickel, and in rare cases, the mercury used in dental fillings could cause that sensitivity.
• Formaldehyde.
• Medicines, such as neomycin, an antibiotic applied commonly to the skin to kill infections.

An important point to remember is that any sensitivity to any substance, including metals, can be corrected only by the avoidance of that substance.

What other factors could cause nummular dermatitis?

• The chances of nummular dermatitis increases in areas of too cold or dry climate.
• Xerosis is a condition where a person has very dry skin. This could result in the chances of getting nummular dermatitis.
• The presence of another type of eczema, mainly atopic dermatitis or stasis dermatitis, on the skin
• Poor blood flows and swelling in the legs.
• An injury or a break in the skin, it could be from an insect bite, contact with chemicals, or an abrasion.
• A skin infection caused by bacteria, an example being Staphylococcus aureus.

Isotretinoin is a medicine used in the treatment of severe acne. When taken, it could increase the risk of this skin problem. So also a medication such as Interferon can worsen the spread of nummular dermatitis.