Sunscreen - Physical vs. Chemical

Sunscreen 101 : Part 1 Next » Sunscreen: Part 2

Sunscreen 101

Part 1: Physical vs. Chemical Sunscreens
Part 2: What to Look for in a Good Sunscreen
Part 3: Wear Sunscreen the Right Way

Part 1: Physical vs. Chemical Sunscreens

There are two general types of sunscreens, physical and chemical ones. Their differences and similarities are explained in the table below. Nowadays there are also sunscreens that contain both chemical and physical UV filters.

	PHYSICAL	CHEMICAL
How they work	Physical sunscreens protect your skin from the sun by deflecting/blocking the sun's rays.	Chemical sunscreens work by absorbing the sun's rays.
Other names	Sunblock	Organic sunscreen
UV filters (the active ingredient in sunscreens that protects you against the sun) For more information about UV filters, their description, and other sunscreen ingredients check here.	Titanium dioxide, zinc oxide	Octylcrylene, avobenzone, octinoxate, octisalate, oxybenzone, homosalate, 4-MBC, Mexoryl SX and XL, Tinosorb S and M, Uvinul T 150, Uvinul A Plus
Stability	Generally stable	Most are stable, but some are not. Avobenzone is notoriously unstable. However, it can be stabilized when formulated in conjunction with other UV filters.
Comedogenicity	Titanium dioxide can be problematic for some people	Chemical filters tend to be more irritating to skin
Protection	How much protection is offered depends on the particle size of the UV filters and overall product formulation. Zinc oxide and titanium dioxide helpful in protecting against UVB and UVA rays, but not the full spectrum of UVA rays.	Chemical filters offer more coverage against UVA and UVB rays than physical sunscreens. Avobenzone, for example, protects against the full spectrum UVA rays.

Physical sunscreens tend to be better tolerated by most skin types because the chemical filters used in chemical sunscreens can be irritating for many people. However, physical sunscreens tend to leave a white cast or white streaks after application and don’t offer as much UVA protection compared to chemical sunscreens. Since they each have their pros and cons, many of today's sunscreens also contain both physical and chemical UV filters.

However, knowing whether a sunscreen is physical, chemical or both does not tell you enough information about whether or not a particular sunscreen will be a good, protective one. Did you know that moisturizer or makeup with SPF doesn't offer adequate sun protection? Do you know the PPD of your sunscreen and how it can prevent your skin from aging? Do you apply enough sunscreen to your skin?

To answer these questions and learn more about how to choose a good sunscreen, move on to part 2!

Next » Sunscreen: Part 2