There are two main classifications of body moisturizers: occlusives and humectants. Occlusives block water from evaporating from skin cells, while humectants draw more water toward the surface of the skin from inner layers. Petrolatum (a.k.a. petroleum jelly) and lanolin are two of the most effective occlusive agents found in many daily body moisturizers. These daily skin care formulas provide a longer-lasting barrier against water loss from the skin. Lanolin can cause an allergic reaction in some people, however. Vitamin and botanical oils are among some of the newer natural ingredients showing up in body lotions that dermatologists recommend for their hydrating effects as well. These include vitamin E, argan, safflower, olive and walnut oils [source: Wright].
Humectants can also combat dry skin. These are usually oil-free and include ingredients such as glycolic acid, urea and lactic acid. Unlike occlusives that merely stop water from exiting the skin, humectants can penetrate the skin to improve water-retention [source: Fordyce].