As potent and powerful as some of our favorite beauty products can be, their kryptonite happens to be the sun. We may love to display them on our vanities, but this can actually make them less effective – obviously not what we want to do to our beloved creams and scents. We talked to a couple of experts to find out why this unfortunate phenomenon occurs and which beauty products to keep in the dark.
Sunlight can feed the bacteria in your products. If you want a plant to grow, you place it somewhere sunny. Microorganisms have a way of behaving similarly. Bacteria may be naturally present in some beauty products, and doubly so if your fingers or skin come in contact with it. Since you can never really know at what point it goes from being harmless to substance-altering, keeping certain skin care and makeup products (particularly liquids) in the dark can help to prevent the sun from exacerbating any bacterial growth. If you start to notice an odor that wasn’t there before in your creams, serums, and liquid makeup, that’s an indicator that bacteria has built up inside it, fueled by UV light.
Joanna Vargas, celebrity facialist and founder of her eponymous salon and skin care collection, agrees, saying, “Any skin care is damaged by the sun. Bacteria can grow in them and ingredients can be altered and die. I wouldn’t ever have them in the sun to begin with.”
UV light can break down some active ingredients. A general rule of thumb is that if a skin care product is only meant to be applied at nighttime, it generally should never see the light of day. Active ingredients in the antioxidant family are particularly vulnerable to sunlight. Dr. Elizabeth Tanzi, clinical professor at the George Washington Medical Center and founder/director of Capital Laser & Skin Care, warns against products that don’t protect themselves from sunlight. “You should never buy a Vitamin C product in a clear container!” she says. “The sun will degrade them so they aren’t as effective. Also Retin-A is photo-unstable so it’s best to be used only at night.” Antioxidants have a way of visually oxidizing— if there was a drop of a potent vitamin C serum on your counter exposed to sunlight, in several hours it will darken in color drastically. If you notice any darkening of color in a skin care product, the culprit is almost always UV light.
Vargas says that’s the reason these products are packaged in brown bottles or plastics with color—”so sun can’t get in!” She also notes, “There’s a UV protective coating that can go into the outside of bottles in a factory before filling.”
It can also turn scents south. Taking everything we know about how UV light can deteriorate skin care active ingredients, it can also alter the chemical makeup of your fragrances. Unfortunately though, perfumes tend to come in pretty clear bottles, making them super vulnerable to UV light’s manipulation. David Pirrota, a beauty and grooming expert and rep for Madrid-based Fragrance label, Oliver&Co, explains that “sunlight is ultraviolet radiation—many of the molecules used in perfumery can react with UV radiation and chemically change to something less pleasant to smell. This causes some of the more volatile components in perfumes to break down.” While a slow change, the eventual change usually is not for the better. Pirrota also mentions that sunlight has the ability to darken the color of a fragrance—a sure sign that it’s had too much time exposed.