a: This is an important question in light of the current controversy regarding the need for sun exposure to maintain adequate vitamin D levels. Many dermatologists find that almost all of their patients show vitamin D levels below the normal range. This is not quite as surprising when one realizes that the minimum laboratory normal lower limit value for vitamin D has been raised. I believe this change in the laboratory normal range is partially responsible for the current media issues regarding vitamin D deficiency in this country. Thus, replacement of body vitamin D stores followed by daily oral vitamin D supplementation is currently recommended by many endocrinologists. The body stores can be replaced with prescription vitamin D in the dose of 50,000 IU for two weeks followed by daily supplementation of 800 IU. This will supply all the vitamin D required for the mature adult to maintain good bone health and will eliminate the need for sun exposure. There is no doubt in my mind that oral vitamin D supplementation and the use of sunscreens is a better way to maintain bone health than frequent unprotected sun exposure.
Q: What is the proper order for the application of medications, cosmetics and skincare products?a: It is very important that skincare products are applied in the proper order. For example, if a topical medication is placed on top of a sunscreen, it will not work, since the sunscreen will create a barrier to medication penetration.
Remember that, in order for a medication to work, it must touch the skin surface. For this reason, the prescription medication is always the first product applied to a clean, washed face. Most topical medications contain penetration enhancers to help the medication go into the skin so that the medication is effective. To work, this must go against the skin before other products are applied.
After applying the medication, the next product applied should be a moisturizer. The moisturizer may actually enhance penetration of the medication; also, the formulation of moisturizers is also such that they generally won't interfere with the active ingredients in the medication that was applied first.
Following moisturizer application, the sunscreen should be applied. Conveniently, some moisturizers can also contain a sunscreen, so you kill two birds with one stone.
Next, the facial foundation should be applied followed by powder, blush and any other colored cosmetics desired.
To summarize, the proper order for product application is always: Medication, moisturizer, sunscreen, facial foundation, powder, blush and other colored cosmetics. This optimizes the functioning of the medication and allows the best final cosmetic appearance.
Zoe Diana Draelos, M.D., is a clinical associate professor of dermatology, Wake Forest University School of Medicine, Winston-Salem, N.C., and is the primary investigator of Dermatology Consulting Services, High Point, N.C.