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

Ask me your skincare question!

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

  • All our content is written and researched by myself.
  • My medical office in Seattle has treated thousands of patients for 15+ years.
  • This site is not affiliated or financially tied to any product, treatment or device.
Ask Me Something
SkinTour Skincare
One of the best investments in your skin is your daily skincare. Why? Because you can prevent many problems with blotchy skin color, lack of glow, texture, some types of acne, and fine lines with good skincare products. You can also correct some of these problems with effective skincare products. Great skincare is often more expensive because quality ingredients are expensive. Some companies spend on research/development which benefits all of us and adds to the cost. Are they worth it? In general - yes! I have handpicked some of what I consider to be the best skin care products, and offer them for sale on SkinTour's shop. This is based on my team and I's testing and research at our clinic. Many of the products are in my own regimen. What could be better than using skin care products a dermatologist uses?!