What causes skin bumps?

Small rough bumps on the outer arms or thighs can fit keratosis pilaris, where keratin plugs hair follicles. Folliculitis tends to create tender or itchy bumps centred on hairs, sometimes after shaving, sweating, or friction. Heat rash produces prickly bumps when sweat ducts become blocked. Milia are firm, pale keratin cysts, often around the eyes. Dermatosis papulosa nigra causes small dark raised spots, while lichen planus can produce itchy, purplish bumps. A soft stalk-like growth may be a skin tag.

Avoid squeezing, picking, or scrubbing bumps, which can cause inflammation and marks. Use gentle cleansing, shower after heavy sweating, and choose loose clothing in hot weather. Pause a new cosmetic or shaving product if the timing suggests irritation. A clinician can distinguish a follicle problem from a cyst, mole, wart, or other lesion and can discuss options such as skin tag removal when a growth catches on clothing or causes irritation.

Arrange an examination if a bump is changing, bleeding, repeatedly crusting, painful, firm and fixed, or different from others. Seek prompt care for rapidly spreading redness, warmth, pus, fever, or severe tenderness. Sudden widespread bumps with facial swelling or breathing difficulty require emergency help, especially after a new medicine or food.

What features identify this bump, and does it need a closer examination or sample? Could shaving, heat, a product, or a medicine be contributing? What treatment is appropriate, and how can I reduce irritation or scarring?