What should you know about purple skin rash?

Purple colouring may come from inflammation, changes in tiny blood vessels, or blood collecting beneath the skin after pressure or injury. A rash may be flat or raised, itchy or tender, scaly, blistered, or warm. The pattern matters: patches in folds can occur with irritation such as intertrigo, while itch and exposure to a new product can point toward contact dermatitis. Other possibilities include atopic dermatitis, psoriasis, heat rash, ringworm, scabies, or a reaction to a medicine. Colour alone cannot identify the cause, and skin tones can alter how redness and inflammation appear.

Take a clear photograph in natural light and record when the rash began, where it started, and whether it is changing. List new medicines, supplements, foods, skin products, detergents, travel, heat exposure, and recent illness. Wash gently, avoid scrubbing, and pause any newly introduced product on the area. Keep the skin cool and dry, and do not scratch or apply a strong steroid or antibiotic cream without advice. A clinician may need to examine the rash and review the pattern rather than relying on colour alone.

Seek urgent medical help if the rash appears suddenly with trouble breathing, swelling of the lips or face, faintness, confusion, severe illness, or blistering of the mouth or eyes. Prompt assessment is also sensible when purple spots do not fade with gentle pressure, spread quickly, become painful, or occur with fever, unusual bruising, or bleeding. Arrange a routine appointment if the rash persists, recurs, or is not improving with simple skin care.

Ask what features suggest inflammation versus bleeding under the skin, whether a medicine or exposure could be involved, which products are safe to use, and what changes should trigger urgent review.