Any dermatologist will tell you that sunscreen should be your constant companion all year long—but especially in the summer months. This topical product protects your skin from ultraviolet (UV) radiation with physical blockers that either reflect or absorb UV rays—so it pays to always have a bottle in your purse, beach bag, and car. Despite the fact that sunscreen is a necessity, many myths persist about how—and even if—the product works.
“Sunscreen is crucial in preventing sunburn, premature skin aging, and reducing the risk of skin cancer. It is absolutely necessary in every skin type,” explains dermatologist Dr. Divya Shokeen. Research shows that wearing SPF 15 or greater each day can reduce your risk of developing squamous cell carcinoma (the second most common cause of skin cancer) by about 40% while lowering your melanoma risk by 50%. However, the American Academy of Dermatology recommends daily use of sunscreen that’s at least SPF 30.
In order to reap all these SPF benefits, it’s crucial to apply and reapply sunscreen correctly. Below, dermatologists walk you through exactly how to do that by debunking common myths and misconceptions about this essential skin-care product.
Myth 1: I only need sunscreen on sunny days
If you look outside on a cloudy day and think, “looks like I’m off the hook for sun protection today,” it’s time to think again. “UV radiation can still be harmful on cloudy or overcast days. Up to 80% of UV rays can penetrate through clouds, so wearing sunscreen daily, regardless of the weather, is crucial,” says Shokeen.
It’s also false that you don’t need sunscreen inside, according to dermatologist Dr. Brendan Camp. “Windows allow the passage of UVA rays, which can damage dermal structural proteins like collagen and elastin and contribute to sunburn formation,” he explains. Rain or shine, indoors or outdoors, you need to apply (and reapply) that SPF.
Myth 2: All sunscreens are “toxic”
“Sunscreens undergo rigorous safety testing and must meet regulations before being approved for use,” says Shokeen. “The ingredients used in sunscreens have been evaluated and deemed safe by regulatory bodies.” She recommends seeking out sunscreens that include zinc oxide or titanium dioxide if you prefer a more “natural” product.
Myth 3: Applying sunscreen once is enough for the day
While many people put sunscreen on in the morning and call it a day, Shokeen says we should all be reapplying more often. “Sunscreen should be applied generously and evenly at least 15 to 30 minutes before sun exposure. Reapply every two hours, or immediately after sweating or swimming, as sunscreen can rub off or lose its effectiveness over time,” she says.
Myth 4: Higher SPF means longer protection
The term “SPF” stands for sun protection factor, and it tells you how much protection it offers against UVB rays, which are the type of rays that cause sunburn. “SPF 30 provides adequate protection, blocking about 97% of UVB rays, while higher SPFs only provide a slight increase in protection,” says Shokeen. “Reapplying sunscreen frequently is still necessary regardless of the SPF level.”
Myth 5: Sunscreen never expires
Sunscreen expires just like food or makeup. “Check the expiration date on your sunscreen. Expired sunscreens can have an altered consistency and active ingredients may degrade over time, which can affect the efficacy of the product,” says Camp.
Generally speaking, sunscreen last about three years. Many bottles say something like “12M” or “18M,” indicating how long the product will last once you open it. Others may have a tiny barcode or icon declaring their shelf life.
Myth 6: Some sunscreens are waterproof
“No sunscreen is waterproof,” says Camp. “The American Academy of Dermatology recommends using a sunscreen that is water resistant. Water resistant means how long a sunscreen will stay effective on wet skin.” After sweating or swimming, you will still need to reapply sunscreen—regardless of whether or not it’s “water resistant.”
Myth 7: Sunscreen is the only thing you need to protect yourself from the sun
Yes, sunscreen is essential, but it shouldn’t be the only thing protecting you from the sun’s rays. “No sunscreen offers 100 perceny protection from UV radiation,” says Dr. Camp. “Compliment the use of sunscreen with sunglasses, a wide-brimmed hat, UPF clothing, and avoidance of the sun during peak hours of the day (10 a.m. to 4 p.m.).”
Yearly skin checks are also an important part of your sun protection routine. “Regular skin checks and consultations with a dermatologist are also important to detect any skin changes or abnormalities promptly. Taking these proactive steps can help maintain healthy skin and reduce the risk of sun damage and skin cancer,” says Shokeen.
