What should you know about coin eczema?

Coin eczema, also called nummular eczema, appears as sharply outlined patches that may resemble coins. The surface can feel dry and rough, and itching may be strong enough to disturb sleep. A patch can start after dry skin, irritation, an insect bite, or minor skin injury, although the trigger is not always clear. Scratching damages the outer barrier and can make the patch larger or more inflamed.

The appearance can overlap with fungal infection, contact dermatitis, psoriasis, or an infection. A clinician may need to examine the edge, scale, distribution, and treatment response before deciding what it is. Coin eczema is a skin pattern, not proof that a particular food or allergy caused the rash. Darker marks may remain after inflammation settles; this is called Post-Inflammatory Hyperpigmentation.

Use a fragrance-free moisturiser generously and often, especially after a short lukewarm wash. Choose gentle cleansers, avoid scrubbing, and keep nails short to reduce injury from scratching. Wool, fragranced products, harsh detergents, and very hot water can aggravate some patches, so note what happens after exposure rather than assuming one trigger.

A clinician may recommend a topical anti-inflammatory medicine, an antimicrobial treatment if infection is present, or another option based on the examination. Do not apply steroid or antifungal combinations indefinitely without guidance. If itching is worse at night, discuss a plan that protects sleep and prevents scratching. Related information on Itchy Skin, Dry Skin, and Crusted Skin can help you describe symptoms accurately.

Arrange medical review if the rash is spreading, recurring, painful, or not improving with gentle care. Seek prompt help when redness is rapidly expanding, the area becomes hot or very tender, or there is pus, honey-coloured crusting, fever, or feeling unwell. Urgent assessment is appropriate for swelling of the face, breathing difficulty, or a severe reaction after a product.

Could this be coin eczema or another round rash? Do I need a skin scraping or other test? Which moisturiser and prescribed treatment should I use, and for how long? What signs suggest infection? How can I reduce night-time scratching? Could a medicine, product, or workplace exposure be contributing?