What's the difference between chemical and mineral sunscreen?
If I could offer you only one tip for the future, sunscreen would be it
In Mary Schmich's (and later Baz Lurhman's) eternal words: "Ladies and Gentlemen of the class of '99 Wear sunscreen If I could offer you only one tip for the future, sunscreen would be it."
In a nutshell, chemical sunscreens use particular chemicals - usually a combination which may include oxybenzone, avobenzone, octisalate, octocrylene, homosalate, and octinoxate, to shield your skin by absorbing the UV rays which enter and releasing them as heat. Mineral - also referred to as physical - sunscreens use naturally shielding ingredients such as zinc and titanium oxide to physically reflect UV rays away from the skin.
So why use one type of sunscreen versus the other?
Physical sunscreens naturally offer broad-spectrum protection as they work by blocking the rays entirely. They often last longer and are usually a better choice for sensitive and blemish-prone skin as their ingredients are less likely to cause a reaction or irritation. On the other hand, their ingredients and thickness means they are more likely to leave a white cast on the skin and are more vulnerable to rubbing off due to physical activity, Chemical sunscreens are more available in the market and tend to be lighter and easier to spread and apply, however they usually require a 15 to 20 minute wait period before they can begin to work. They comparably do not last as long on the skin and can also be pore-clogging for some skin types and may cause irritation - the risk of which is increases with higher SPF. The broadest, highest coverage formulas are usually the most irritating due to the combination of chemicals required to achieve that level of protection.
If you are conscious about what chemicals go into your sunscreen, it is important thing to bear in mind that not all chemical formulas are created equal and some are safer to use than others. We recommend you check the Environmental Working Group's Skin Deep Cosmetics Database which rates skincare ingredients based on their potential toxicity.