Those annoying small bumps that seem to show up on your legs and arms -- especially when the air gets a little dry -- is commonly recognized as Keratosis pilaris. This skin issue is a direct result of excess skin cells forming around hair follicles. Although harmless and currently without a cure, the genetically inherited ailment is best treated by keeping those bumps at bay through an aggressive skin-care regimen.
Exfoliate on a regular basis. This is most commonly done in the shower using a body wash with a mild abrasive. You can also team this with an exfoliating shower mitt to reduce extra dead skin cells that directly contribute to the appearance of bumps.
Apply a small amount of a vitamin A-based skin cream directly to the affected area. Use caution though -- aggressive use can lead to parched skin. You can also use vitamin A caplets punctured or broken in half, applying the fluid directly to problematic areas.
Use a low-sulfate soap. Many moisturizing body washes contain less of this skin-irritating ingredient than comparable bar soaps. Compare labels between bar soaps if you prefer their use.
Consider visiting your doctor to get a prescription-based topical ointment. These applications affect your immune system's response on the treated area. Similar to medication used for treating eczema, this is often only prescribed when little else proves effective.