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Friendly Fridays Q&A: When is the Best Time to Use Each Skin Care Ingredient?

Posted May 27 2011 6:57pm

In honor of relaunching this month as a daily beauty blog, I’ve decided to make every Friday “Friendly Friday,” in which I will answer a favorite weekly question from a reader.

This week’s question:

When is it the best time to apply different types of skincare ingredients?  I am confused.  I’ve been using vitamin C, vitamin E, retinoids, and peptides.  Please help!” -Confused

Dear Confused,

There are two issues at play here.  The first is that you want to stagger your ingredients around UV exposure.  Some ingredients are best for day, such as antioxidants vitamins C and E, because they boost sunscreen protection.  Other ingredients should be reserved for night, like retinoids or alpha hydroxy acids, because they can thin the skin and make it more susceptible to UV damage.  A complete list of each kind is shown below.

Ingredients best for day:

  • Vitamins C and E – In conjunction, can boost UV protection when used under sunscreen.  (Ideal concentration:  vitamin C 15% or higher; vitamin E 2% or higher).
  • Argan oilArgan oil contains a high concentration of vitamin E.  As such, it may boost sun protection and protect against oxidative damage as well.
  • Sunscreen - This should be a “duh!” Michelle Tanner-type moment, but I added it here for the sake of completeness.

Ingredients best for night:

  • Peptides – Although peptides can also be used during the day (they have not been shown to increase UV sensitivity), peptides also stimulate collagen production, which is a process that takes place over the course of weeks to months in the fibroblasts.  To stimulate such a tenuous process, it is best to apply the ingredient at night, when the basal cell temperature is somewhat higher, and the ingredients can penetrate further.
  • Retinoids – Increase UV sensitivity.  Also, retinoids stimulate collagen production; see above.
  • Human growth factors - The verdict is still out on whether or not these products work , although several top dermatologists recommend them in the meantime.  To optimize your chances, continuing with the above logic, use them at night.
  • Hydroquinone – Although hydroquinone is used to treat sunspots and irregular pigmentation, it has been associated with onchronosis, a darkening of the skin, in darker-skinned patients.  For this reason, some dermatologists recommend using hydroquinone at night, decreasing the chance for UV-induced onchronosis to occur.

The second issue when you are combining products from different lines is that you do not want to use  ingredients together that can inactivate each other.  For instance, retinoids have an optimal pH of 5.5-6.0 , while alpha hydroxy acids work best at a pH of 3.0-4.0 .  If you use them together, it is likely the average pH is going to be outside the range that is optimal for each ingredient.

It is worth it to note that some skin care formulations are now being produced that are not as susceptible to suboptimal pH levels, due to microencapsulation (ingredients are released somewhat deeper in the skin before release), suspension in different layers of an emulsion (ingredients do not mix), and other techniques.  Still, if you are mixing products from different lines or brands, it is best to stick with the time-tested rules, and do not use the following in conjunction:

  • Nicotinamide/niacinamide and sirtuins. Niacinamide turns off sirtuin activity, as established in a 2005 study at Johns Hopkins University .
  • Retinoids and alpha hydroxy acids or beta hydroxy acids. As previously mentioned, the optimal pH level of retinoids is higher than that of the hydroxy acids, rendering each ingredient to be less effective.
  • Retinoids and vitamin C. Although you see this combination a lot in drugstore products, again, it’s simply an issue of pH:  retinol esterification occurs optimally at a pH of 5.5-6.0, while vitamin C is most active at a pH of approximately 3.0-4.0.

I hope that this answered your question, Confused!  If you have a question you’d like to see answered here next week, please feel free to send it to nicki[at]futurederm[dot]com.

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