"I've seen recipes for sunscreen involving a mix of a carrier oil, like coconut, and zinc oxide. I'm concerned about the toxic chemicals in store bought sunscreen, so I've been considering making one of these recipes. Are they effective to use?" -Sara
The short answer: no.
Sun protection is important all year round. No matter how old you are, or if you plan to stay inside all day. The daily application of sunscreen is a must if you want to prevent signs of premature aging.
Sunburns come from UVB rays when we spend too much time unprotected in direct sunlight. But UVA rays don't cause burns, rather they cause damage to a deeper layer of skin, and this is what causes wrinkles and sunspots. Both UVB and UVA rays contribute to skin cancer.
There is a common belief within the all-natural community that sunscreen is toxic and unhealthy to use long-term. It's valid that some chemical sunscreens contain harmful ingredients which may be endocrine disrupters (Suh, Susie, et al. 2020). But mineral sunscreens, containing zinc oxide and titanium dioxide are regarded as safe and effective by the FDA (FDA Advances New Proposed Regulation to Make Sure Sunscreens Are Safe, 2019).
The concern over questionable ingredients in cosmetics has caused many of us to look for natural alternatives to make at home. The internet has hundreds of posts on DIY (Do It Yourself) sunscreen recipes, but are they effective at protecting the skin from both UVB and UVA rays?
The Issues With Making Sunscreen At Home
Zinc oxide is an effective active ingredient in sunscreen, but it is tricky to work with. It clumps easily and requires the perfect combination of ingredients to suspend it evenly on the skin to create a reliable SPF coverage. When making a DIY sunscreen made from 2 ingredients (an oil or butter, like coconut oil, and zinc oxide) the zinc oxide cannot be distributed evenly throughout the product, and produces an application with patchy coverage.
Sunscreen has to be thoroughly tested for effectiveness to make it to the market. Clinical testing isn't a viable option for your homemade product, and so you'll never know the SPF of the sunscreen you’ve made.
No matter how much zinc oxide you put into your recipe, the SPF is not a guarantee. There's no way to have a reliable SPF rating for your sunscreen unless you have the proper formulation to keep the active ingredients suspended in an even coverage over the skin. Some online recipes for DIY sunscreen claim to know an approximate SPF rating, but it cannot be trusted.
Some people say that if you're not getting burned, the sunscreen is working. But this isn't accurate. UVB rays cause skin redness and burns, but UVA rays cause damage to deeper layers of the skin and leads to premature signs of aging, such as loss of skin elasticity, wrinkles, and dark spots. So even if you do not have a sunburn, it does not mean that the sun is not damaging your skin. Zinc oxide has anti-inflammatory properties that can cover up the signs of burning as well. So you may think that you're not getting burned, until the next day when burn appears.
Years ago, when I refused to use any skincare product that wasn't "natural" because I believed that synthetic chemicals were dangerous, I used a coconut oil and zinc oxide sunscreen blend that I got at a farmer's market. Now I look back on this with horror, because the main issue with DIY sunscreens is that there is NO way to tell how effective the product is. Not to mention the hideous white cast it left on my face.
But now I know better! I use store-bought sunscreens that I trust to work and leave formulating to the professionals.
My Favorite Mineral Sunscreens
La Roche-Posay Anthelios UV Correct Moisturizer SPF 70
EltaMD UV Clear Broad Spectrum Face Sunscreen SPF 46 for Sensitive Skin
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Commissioner, Office of the. “FDA Advances New Proposed Regulation to Make Sure That Sunscreens Are Safe and Effective.” U.S. Food and Drug Administration, FDA, https://www.fda.gov/news-events/press-announcements/fda-advances-new-proposed-regulation-make-sure-sunscreens-are-safe-and-effective.
Suh, Susie, et al. “The Banned Sunscreen Ingredients and Their Impact on Human Health: A Systematic Review.” International Journal of Dermatology, U.S. National Library of Medicine, Sept. 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7648445/.