If you look in the store, you'll find moisturizing products with and without sunscreen in them, often with no difference in price. Since having a sunscreen in a moisturizer can simplify your skin care regimen, it might seem to make sense for all moisturizers to include a sunscreen. However, there are many reasons these products still exist separately.
First, because sun protection is so important, sunscreen may be included in a variety of cosmetics and skin care products. For example, some foundations contain sunscreen, and if yours does, you don't need to have them in both products. If both your foundation and your moisturizer contain an SPF 15 sunscreen, it doesn't mean you've doubled your protection to SPF 30. You've just applied a little extra sunscreen.
Also, sunscreen is necessary only during daylight hours, so when you use a moisturizer at night, it may not make sense to use a sunscreen as part of it. Similarly, there might be times when some parts of your body require only a moisturizer, but not a sunscreen. For example, in the winter, your dry feet probably don't get sun exposure, but still might need a moisturizer.
One interesting difference between moisturizers and sunscreens is that the U.S. Food and Drug Administration classifies these products differently. Moisturizers on their own are considered to be cosmetics, meaning they're applied with the intent of cleaning, beautifying or changing the appearance of the body. Because the active ingredients in sunscreen are designed to prevent disease, they are classified as drugs. Drugs have stricter government regulations and must go through an approval process before going on the market. Cosmetics -- unless they contain certain color additives, which could cause allergic reactions -- usually are not subject to these same stringent guidelines [source: FDA].
What is it in sunscreen that makes the FDA take notice? If you remember from the last page, physical sunscreens often contain titanium dioxide or zinc oxide, which may block pores, irritate skin and increase oiliness. If you already have oily skin, this could be a nightmare for you. Ingredients in chemical sunscreens can also irritate skin in a number of ways, by causing dryness, swelling and redness, for example. People with sensitive skin need to be especially cautious about choosing sunscreen, and moisturizers with sunscreen may have the active ingredients combined in such a way that will irritate certain skin types. This can be a factor in why people will choose separate products [source: Begoun: Sunscreen]. As a result, be sure to understand the active ingredients of the products you use and how they affect your skin.
Learn more about sunscreen, moisturizers and other products to protect your skin by visiting the links on the next page.