What is a mineral or physical sunscreen?
Physical sunscreens consist of mineral ingredients namely, zinc oxide and titanium dioxide. They work by sitting on top of the skin and they reflect and scatter light in a similar way to clothing.
Zinc oxide protects against a wide range of UVA including UVA 1 (340 to 400 nm). It is very photo-stable and does not react with other UV filters. It is more effective than titanium dioxide in regards to UVA protection however, it is less efficient against UVB radiation. Titanium dioxide protects against UVA 2 (315-340 nm) and UVB, but does not protect against UVA 1 as does zinc oxide.
What are the pros and cons of physical sunscreens?
Physical sunscreens work as soon as they are applied on the skin. They are unlikely to irritate the skin so they are good for sensitive skin types. They can also be good for rosacea skin types or patients with redness as they deflect heat from the skin. They are less likely to be pore-clogging so they are good for acne-prone skin.
They also last longer when in direct UV light, however, they can be rubbed off much more easily than chemical sunscreens especially if in contact with sweat or water. They can often leave white streaks or a white chalkiness on the skin so they are not ideal for under make-up and can be difficult to use for darker skin tones. They tend to be thicker requiring more effort to rub in. They also tend to have a longer shelf life.
What is chemical or organic sunscreen?
Chemical sunscreens contain organic (carbon-based) compounds e.g. oxybenzone, octinoxate, octisalate and avobenzone. They create a chemical reaction and work by changing UV rays into heat and then release that heat from the skin. They consist of UVA and UVB blockers. Their structure allows for light to be absorbed.
What are the pros and cons of a chemical sunscreen?
They are usually thinner formulations which makes application easy, they do not cause much white streaking and spread easily. They are much more resistant to sweat or water compared to a physical sunscreen. They only start to be effective about 20 minutes after application to the skin and they require frequent reapplication as its protections get used up more quickly in direct sunlight. They are more likely to be irritating and the higher the SPF, the higher the risk of irritation. They can increase redness in rosacea-prone skin types and they can also clog pores causing an acne flare.
Physical vs chemical sunscreen, which is best for you?
The simple answer is… the one that feels the most comfortable on your skin. If you’re an oilier skin type you will want to choose one that is lightweight and not greasy. If you have sensitive skin that gets red easily you’ll want to find one that doesn’t irritate. If you have a darker skin tone you will want to choose one that doesn’t look chalky on the skin.
Both chemical and physical sunscreens do a great job of protecting your skin from the sun. The most important thing is to find a sunscreen that you like the look and feel of so that you are inclined to use it frequently and reapply regularly.
If you are concerned about the compatibility of your skin and a new sunscreen performing a simple patch test on your inner arm is a good idea, before using it all over your face.