Red or white bumps on the back of the arms is a condition called keratosis pilaris, according to About.com. Keratosis pilaris is not acne. It is a genetic follicular skin condition that affects 80 percent of adolescents and almost half of the adult population.
Keratosis pilaris occurs when the skin produces excess keratin and begins to plug hair follicles. Topical treatments such as retinol products and moisturizers with lactic acid or urea effectively treat this condition, according to About.com, as do preventative measures such as avoiding hot showers and scrubs.
The Doctor Oz Show states that keratosis pillars is a hereditary trait that is medically harmless. Flareups are more likely to occur more often during puberty, but keratosis pilaris often decreases with age.