If I mix two sunscreens, will it dilute them? Also, what about La Mer.

Hi Dr. Irwin, what is your take on the La Mer products? Are they truly worth the investment? Also, on an unrelated question, will mixing different products at different SPFs dilute the strength? I am mixing two makeup foundations (one with SPF 25, the other SPF 15). What will the SPF be when I mix the two together? Thanks

On sunscreens, no it won’t dilute them.  If anything, if you layer them over each other, you will get more protection.   In general though, make-up doesn’t contain very effective sunscreens unless it’s mineral based makeup like the Jane Iredale.  To get good UVA protection you want to look for zinc or titanium at least 10%.   Better would be to use a slightly tinted mineral block sunscreen like the Elta MD Physical 41 or SkinCeuticals and then put the foundation with sunscreen over that.

Many people like La Mer.  It’s definitely a product for very dry skin.  There are many other moisturizers just as good that are less expensive (Vivite is similar) , so in my opinion, it’s not worth the money.    Dr. I

Dr. Brandith Irwin, MD

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Hi, I’m Dr. Irwin. I believe that consumers deserve a medically trained and unbiased skincare advocate.

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