Small red bump on the forearm: what to know

A bump centered on a hair and tender after sweating or friction can fit folliculitis. Many rough, tiny bumps on the outer upper arms can fit keratosis pilaris, where keratin blocks follicle openings. Itchy clusters after heat or occlusion can occur with heat rash. A firm, flat-topped, purple-red or scaly lesion needs examination because inflammatory conditions such as lichen planus can look different from a simple bite. A pearly white, firm bump may be milia. Record when it appeared and whether it is changing.

Keep the forearm cool, rinse away sweat, and use a gentle fragrance-free cleanser. Avoid scratching, squeezing, rough exfoliation, and tight clothing over the area. Stop a new fragranced product if the bump appeared soon after using it. For repeated itchy bumps, a clinician may discuss an antihistamine treatment; do not start one without checking whether it suits your health and other medicines. Persistent single lesions should be examined before any removal treatment is considered.

Seek prompt care if redness expands, the area becomes hot and increasingly painful, pus develops, or fever appears. Get urgent help for facial swelling, breathing trouble, faintness, or a rapidly spreading rash. Arrange a routine dermatology assessment when a bump lasts, bleeds, crusts, changes shape or color, or keeps returning.

Is the bump centered on a follicle or a different type of lesion? Could heat, friction, or a product be contributing? What symptoms should make me return sooner? Would treatment be topical, oral, or observation?