What should you know about coin shaped skin rash?

Round or oval patches may be dry, scaly, cracked, raised, itchy, or mildly sore. Nummular eczema often forms itchy, coin-like patches on the limbs. A fungal rash such as ringworm can expand with a more active scaly edge and clearer centre. Contact dermatitis may follow exposure to a product, fabric, adhesive, or chemical. Psoriasis can produce well-defined scaly plaques, while heat rash, intertrigo, or scabies may be considered when the location and symptoms fit.

The appearance alone cannot identify the cause. Note when it started, whether it is spreading, recent products or medicines, and whether anyone close to you has a similar itchy rash.

Use a gentle, fragrance-free cleanser and moisturiser, avoid scratching, and keep the area cool and dry. Do not share towels or clothing if the rash could be infectious. Photograph the patch in good light so changes are easier to compare. A clinician may inspect the border and surface, and may recommend a targeted treatment; steroid creams can worsen some fungal rashes when used without the right diagnosis.

Arrange a medical assessment if the rash is spreading, recurring, painful, oozing, crusted, or not settling with gentle skin care. Seek urgent help for rapidly worsening redness, marked swelling, blisters, fever, facial involvement, or breathing difficulty. A new widespread rash after a medicine also needs prompt clinical advice.

Ask what features distinguish eczema from ringworm, whether a skin scraping is needed, which products should be stopped, and how long to use the recommended treatment.