You’ve perused the drugstore counter, sniffed every bottle, checked the ingredients and are convinced that you sunscreen will protect against both UVA and UVB rays – but do you know whether you’ve chosen a photostable sunscreen?
Photostability is the ability of a product to retain its integrity upon exposure to light. In the case of a sunscreen, you will want to ensure that your product of choice doesn’t degrade when the first UV ray hits your skin. As you can imagine, this is an essential quality for any sunscreen.
While sunscreens always display their SPF values (the ability to block UVB rays, which are associated with sunburn), it’s still not easy to tell if your sunscreen will protect against UVA rays or is photostable. Although new regulaions are on the way, manufacturers don’t necessarily inform you as to the photostability of their products. So even though your sunscreen may be broad spectrum, a photo unstable product could leave you at risk not only from sunburn (via UVB rays), but also from longer term skin damage, such as photoaging, wrinkles and even some types of skin cancers via UVA rays.
Choosing a Photostable Sunscreen
It was discovered that avobenzone, one of the most widely used sun filters in sunscreen formulations, degrades rapidly upon exposure to light when it is used by itself. This characteristic decreases avobenzone’s ability to protect against UVA rays. However, when avobenzone is combined with certain ingredients, such as octocrylene, the result is a stable sun filter, which delivers the ability to block UVA rays effectively.
Studies have shown that a range of sun filters including Mexoryl XL, Mexoryl SX, Tinosorb M, Tinosorb S, zinc oxide and titanium dioxide are photostable. As long as they are found in adequate concentratations, sunscreens containing these ingredients will deliver over time.
Photostable Sunscreen Brands
If you’re still confused by the array of sunscreens to choose from, then consider the following brands. All contain photostable sun filters and offer broad spectrum UVA and UVB blocking ability from the sun’s rays: