Itchy rash on the neck, armpits and groin

These areas contain skin folds where heat, sweat and rubbing can weaken the skin barrier. Deodorant, fragrance, detergent, shaving products, tight clothing or a new fabric may trigger contact dermatitis. Moist fold irritation is called intertrigo; a ring-shaped, spreading edge can fit ringworm. Scabies may cause intense itching, especially at night, with small bumps or lines and itching in close contacts. Atopic dermatitis, psoriasis, heat rash or a drug rash can also affect these sites. The rash’s colour, scale, border, symmetry and timing help a clinician separate these possibilities.

Wash gently with lukewarm water, pat dry, and keep each fold cool and dry. Pause newly introduced scented products and avoid scratching, tight clothing and shared towels. Choose loose, breathable clothing and change out of sweaty garments promptly. Do not apply a steroid, antifungal or combination cream to the groin without advice, because the wrong product can mask or aggravate some rashes. Photograph the rash in good light and note recent products, medicines, travel, exercise and whether anyone close is itchy.

Arrange a medical assessment if the rash is spreading, painful, weeping, crusted, recurrent or not settling after removing an obvious irritant. Seek urgent help for swelling of the lips or tongue, breathing difficulty, faintness, widespread blistering, skin peeling, fever with a rapidly worsening rash, or involvement of the eyes or mouth. A clinician may inspect the folds and take a skin sample when a fungal infection is suspected.

Ask whether the fold pattern suggests contact dermatitis, intertrigo, ringworm or another condition. Mention every new medicine and skin product, whether itching is worse at night, and whether close contacts have symptoms. Ask which cleanser, moisturiser or prescribed treatment is suitable for the groin and how long to use it.