The cause of discoid eczema is unknown, although it is often accompanied by dry skin.
One theory is that having dry skin means your skin cannot provide an effective barrier against substances that come into contact with it. A previously harmless substance, such as soap, can then irritate (damage) your skin.
Contact dermatitis, a type of eczema caused by coming into contact with a particular allergen or irritant, may therefore have a role in causing discoid eczema.
Discoid eczema may also be linked to atopic eczema, which often occurs in people who are prone to eczema, asthma and hay fever ("atopic" means the tendency to develop eczema, asthma or hay fever). However, unlike atopic eczema, discoid eczema does not seem to run in families.
Other possible causes
An outbreak of discoid eczema may be triggered by a minor skin injury, such as an insect bite or a burn.
Some medicines may also be associated with discoid eczema, as patches of eczema can appear in people taking:
- interferon and ribavirin – when they are used together to treat hepatitis C, an infection of the liver
- tumour necrosis factor (TNF) blockers – which are used to treat some types of arthritis, which causes pain and swelling in the joints
Dry environments or cold climates can make discoid eczema worse. Sunny or humid (damp) environments may make your symptoms better.
