Physical Sunscreens contain active mineral ingredients, titanium dioxide and zinc oxide, which work by sitting on the surface of the skin to deflect and scatter damaging UV rays away from the skin. These mineral are not absorbed into the skin or the body the way chemical sunscreens are.
Pros of Physical Sunscreen:
- Offers protection against both UVA and UVB rays and is naturally broad spectrum
- Protects from the sun as soon as it’s applied, no need to wait 20 minutes before sun exposure
- Only needs reapplication with excessive sweating or swimming
- Lasts longer when in direct UV light
- Less likely to cause a stinging irritation on the skin, making it better for sensitive skin and for those with heat-activated skin(such as rosacea, acne, and sensitized skin) since it deflects the heat and energy given off by the sun away from the skin
- Non-comedogenic ( pore-clogging), making it ideal for all skin types and conditions, especially those with acne
- Manufactured in tinted (can be worn as make-up) and non-tinted
- Longer shelf life (minerals don’t expire)
Chemical sunscreens work by being absorbed into the skin and are considered organic because they contain carbon-based ingredients such as avobenzone, oxybenzone, octinoxate, and octisalate. Instead of physically deflecting UV light, these molecules absorb UV radiation through their chemical bonds. As the bonds absorb UV radiation, the components of the sunscreen slowly break down and release heat into the surrounding tissues. Because they break down and are also absorbed into the body, it’s important to reapply chemical sunscreens more frequently to maintain sunscreen protection.
Cons of Chemical Sunscreen:
- Must be applied 20 minutes prior to sun exposure to allow the chemicals time to to be absorbed into the skin to work
- Because it penetrates skin, risk of skin irritation is much higher
- Chemical sunscreens break down with sun exposure and need frequent reapplication
- Can cause burning and stinging if chemical sunscreen gets into eyes
- Because chemical sunscreen converts UV rays into heat, the skin temperature is higher. This can cause increased redness/ flushing, or allergic reaction for people with rosacea, sensitive, or sensitized skin or acne. The increased heat also contributes to dark spots (hyper-pigmentation) in those prone to melasma and the formation of hyper-pigmentation.
- Must be used by their expiration date due to degradation of the active chemical ingredients
- May clog pores depending on other inactive ingredients
- The higher the SPF rating, the higher the risk for adverse reactions to the chemicals