skincare · sun protection · sunscreen

The difference between physical & chemical sunscreens and how to use them


We know that sunscreen is important, but did you know there are two main kinds of sunscreen and there is a proper way to use them?

Take a look at the back of the sunscreen you are using right now and check the ingredients list. If it contains words like “zinc oxide” or “titanium dioxide” then it is a physical sunscreen. If it contains ingredients such as “oxybenzone,” “avobenzone,” or “octisalate,” it is a chemical sunscreen.

The main difference in application is that when you use chemical sunscreens, you need to wait 20 minutes before heading outside as it takes that long for the ingredients to activate. For physical sunscreens, you can head outside right away.

Chemical sunscreens work by “changing UV rays into heat, then releasing that heat from the skin,” while physical sunscreens, or physical blockers, work by sitting on top of the skin and deflecting UV rays away from the skin, according to Renée Rouleau

Besides waiting twenty minutes when using chemical sunscreens, here are a few more sunscreen tips I’ve picked up on my skincare journey:

  1. Use a minimum of SPF 30. Anything higher than 50 is more about marketing and isn’t proven to be more effective than lower-SPF sunscreens. 
  2. A higher SPF does not mean you don’t need to reapply it; the American Academy of Dermatology recommends reapplying sunscreen approximately every two hours
  3. Lab Muffin notes that there is a possible incompatibility between certain sunscreen agents that are used together, so be aware of potentially incompatible ingredients (for example, mixing two different sunscreens with different ingredients).

Check out this great video about chemical vs physical sunscreens by Dr. Scott Guenthner of The Dermatology Center of Indiana.

What sunscreen are you using right now? Is it a physical or chemical sunscreen? Do you have a favourite? Please let me know in the comments section below! 🙂


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