What should you know about red pimples on back of arms?

Small, rough, fairly even bumps on the backs of the upper arms can occur when keratin builds up around follicle openings. This pattern may feel like sandpaper and may not contain pus. Red, itchy, or tender bumps after sweating, close clothing, shaving, or waxing can instead reflect inflamed follicles. Acne is another possibility when there are blackheads, whiteheads, or deeper inflamed spots. A rash that is very itchy or extends beyond follicles may have a different cause.

Cleanse without a loofah or rough scrub, and apply a plain moisturiser after bathing. Products containing a gentle exfoliating ingredient may help rough follicle plugs, but introduce one product at a time and stop if burning or marked redness develops. Keep sleeves loose, rinse after sweating, and avoid picking. Improvement can be gradual; persistent bumps should be assessed before adding stronger treatments.

See a clinician if lesions become painful, warm, swollen, crusted, or pus-filled, or if redness spreads. Fever, feeling unwell, or rapid change warrants prompt care. Make an appointment for ongoing itch, scarring, or a pattern that does not respond to gentle measures.

Ask whether the bumps resemble keratosis pilaris, folliculitis, or acne; which moisturiser or exfoliating ingredient is suitable; and whether hair removal or clothing is aggravating them.