If the backs of your arms look like gooseflesh and feel scratchy, like sandpaper, and you're prone to dry skin or eczema, you could have a benign, common condition called keratosis pilaris. (It's caused when keratin, a protein in the skin, forms hard plugs within hair follicles.) Whatever you do, don't try to scrub the raised bits away with rough exfoliants—you'll just irritate the skin, making the bumps inflamed. Instead, use washes and lotions with alpha hydroxy acids (like the Glytone KP Kit, which contains both). Then use a hydrocortisone cream to reduce the redness, and the bumps should clear up in three weeks.