Why does contact dermatitis cause skin redness?

Irritant exposure can disrupt the protective barrier, while an allergen can activate a delayed immune response. Chemical signals then increase blood flow and attract immune cells to the area. Redness may come with warmth, itching, swelling, scaling, burning, or small blisters. On deeper or darker skin tones, inflammation may look brown, purple, grey, or darker than the surrounding skin rather than bright red. The shape and location can reflect where a product, metal, plant, or adhesive touched.

Remove the suspected trigger and rinse the area gently with lukewarm water. Avoid heat, friction, exfoliation, and fragranced products while the barrier is irritated. A cool compress can reduce warmth, and a simple moisturiser may help if the skin is intact. Keep notes about exposures and take a photograph in consistent lighting so changes are easier to describe. A pharmacist or clinician can guide treatment based on the site and severity.

Seek medical advice when redness is spreading, painful, recurrent, associated with blisters or drainage, or not improving after trigger avoidance. Prompt care is needed for marked warmth, swelling, pus, fever, or red streaks. Get emergency help for facial or tongue swelling, breathing difficulty, faintness, or a rapidly developing reaction.

Does the colour and distribution fit contact dermatitis? Could a product or metal be responsible? Which treatment is safe for this location, and should I have patch testing?