Raised bumps on the back of the arms: what to know

Keratosis pilaris commonly creates many small, rough bumps around hair follicles on the outer upper arms. They may feel like fine sandpaper and can be skin-coloured or pink. Folliculitis can instead produce tender, red, or pus-filled spots. Heat, sweat, and friction may trigger a rash, while a sharply itchy or scaly pattern may suggest dermatitis or another condition. These appearances overlap, so the pattern and symptoms matter more than a single bump. Read more about Keratosis Pilaris and Skin Bumps.

Use a gentle cleanser and moisturise after bathing while the skin is still slightly damp. Products containing urea, lactic acid, or salicylic acid may smooth rough follicle plugs for some people, but introduce one product at a time and stop if burning or cracking develops. Avoid abrasive scrubs, picking, and close shaving over inflamed spots. Loose, breathable sleeves can reduce friction and sweat.

See a clinician if bumps are painful, pus-filled, spreading, intensely itchy, or leaving marked dark or light patches. Prompt review is sensible for fever, rapidly expanding redness, swelling, or warmth. If careful skin care has not helped or the diagnosis is uncertain, a dermatologist can distinguish keratosis pilaris from folliculitis and select treatment.

Ask whether the bumps are follicle-related, which moisturiser or active ingredient fits your skin, and how to recognise infection or a treatment reaction.