Whether it's 20 degrees and snowing or 90 degrees and sweltering, sunscreen is always a necessary step. But with seemingly endless options available, how do you know which type to choose? And what's the difference between physical and chemical sunscreen anyway? If they both do the same thing, it seems like it shouldn't matter which type you pick. But depending on certain factors like your skin type and how quickly you want your sunblock to take effect, there's a better choice.
So to find out what exactly makes physical sunscreen different from its chemical counterpart, I emailed with Dr. Elizabeth Tanzi, founder and director of Capital Laser & Skin Care and Assistant Clinical Professor for the Department of Dermatology at the George Washington University Medical Center, and Chris Birchby, founder of COOLA Suncare. Dr. Tanzi and Birchby let me know that the main difference between these two types of sunscreens is how they deal with ultraviolet light. Dr. Tanzi reveals that chemical sunscreens work by absorbing ultraviolet light, keeping it from penetrating the skin and causing damage. On the other hand, "Physical sunscreens work by blocking out ultraviolet light— the light "bounces" off them, rather than being absorbed by the chemical," she explains.
Because of how these two types of sunscreens are formulated, it turns out that each is slightly better suited to different skin types. According to Dr. Tanzi, physical sunscreens are better for sensitive skin-types because they don't contain the same types of chemicals that can cause reactions in sensitive skin. She adds that chemical sunscreens are better for dry skin-types because they can be moisturizing while physical sunscreens tend to be drying. But before you go using one type exclusively, there are some other factors that might determine which type of sunblock is better suited to your needs.
For example, Birchby says that physical sunscreens are typically white and pasty. While this makes them effective at blocking UV rays, it doesn't necessarily make them the best for layering under makeup— especially if you need to take photos. (Whitecast and flashback? No thanks.) And because chemical sunscreens tend to be more moisturizing, they also make for better makeup primers. If your skin is too oily to layer a chemical sunscreen under makeup though, Dr. Tanzi recommends looking for a physical sunscreen in a liquid rather than cream formula.
However, if you need your sun protection to start working ASAP and potentially hold out a little longer, physical is the way to go. According to Birchby, "chemical sunscreen typically requires more time to sink in to become effective." Dr. Tanzi adds that, while it's always best to follow the instructions regarding how long your sunblock will last, "physical blockers can last longer than chemical ones." So especially if you plan on spending prolonged time outdoors, you may want to opt for a physical sunscreen that will go to work immediately and maybe even last longer.
Regardless of which type you go for though, Dr. Tanzi reminds that the most important factor to consider in your sunscreen is that it provides both UVA and UVB, broad-spectrum coverage. That way, whether you're spending the day on the beach or just taking a quick walk outside, you'll be totally protected.