And while most people know better than to expose their skin to sunshine without any sunscreen, sometimes your best efforts to lather up just aren't good enough, according to Lauren Ploch, MD, a board-certified dermatologist and member of the American Academy of Dermatology who practices at the Georgia Dermatology and Skin Cancer Center in Augusta, Georgia.
Here are some scary ways the sun can still damage sunscreen users' skin.
1. You use sunscreen—but use way too little.
Just like using foundation or nail polish, you need to apply enough sunscreen for sufficient coverage. After all, sunscreen will only perform to the full potential of its SPF — i.e., if you're using SPF 30 or higher — if enough sunscreen is applied, according to Dr. Ploch, who adds that skimping on sunscreen will diminish the sunscreen's efficacy. For full-body coverage, she says to apply at least one ounce (aka one full shot glass) of sunscreen. That goes for "natural" or "mineral" formulas, too, which people tend to under-apply since even small amounts can turn the skin white.
2. You use sunscreen—but sweat like crazy.
Even if you lather up from head to toe in your shot glass amount of sunscreen, working up a solid sweat (or simply hanging in a humid environment, which leads to oily, sweaty skin) can completely wash it off your body. Think of sweating as the sticky, stinky equivalent of showering or swimming, two other surefire ways to rinse the sunscreen off your skin and leave you unprotected.
Tip: To properly protect your skin, reapply sunscreen every time your skin gets wet or clammy. And because chemical sunscreens tend to stand up to moisture best, go for a "broad-spectrum" sunscreen, which combines UVB and UVA-absorbing chemicals and ingredients like titanium dioxide and zinc oxide to physically block sun rays.
3. You use sunscreen—but mistake "waterproof" for bulletproof.
Unbeknown to many sunscreen users, "waterproof" formulas won't protect your skin all day, and neither will a sunscreen billed as "water-resistant." (Come on guys, it's not mascara!) Even without swimming or sweating, you'll still need to reapply every 80 minutes, according to Dr. Ploch, since it's only proven to protect you for that long.
4. You use sunscreen—but it underperforms.
A 2016 Consumer Reports test of 65 different sunscreen brands revealed a horrifying truth: Many sunscreen brands don't perform as well as their labels promise. The study favored chemical sunscreens over natural/mineral formulas, or those that rely on ingredients such as titanium dioxide, zinc oxide, or both; threw shade at formulas designed specifically for the face; and surfaced a selection of sunscreen brands that stand above the rest.
5. You use sunscreen—and it burns your skin.
If your skin seems to burn every time you apply a particular chemical sunscreen, it could be the product itself: Occasionally, some sunscreen ingredients (i.e. avobenzone) can cause a photoallergic reaction, a change in the skin that occurs within a few days of exposure, and looks and feels a whole lot like sunburn, according to Dr. Ploch. To see whether the formula is the culprit, switch it up with a mineral sunscreen containing zinc oxide and/or titanium dioxide, which tend to be gentler on sensitive skin. (FYI, despite the Consumer Reports study mentioned above, Dr. Ploch still recommends and personally relies on these natural formulas.)
6. You use sunscreen — but only at the beach.
While beach days (and other outdoor activities) do require a thicker layer of sunscreen for extra defense against the sun, it's also important to use sunscreen for protection on a daily basis. Even if you work in an office and out of direct light, sun rays can go through windows in your car and at work, subjecting exposed skin to damage.
7. You use sunscreen—but then you squeeze calamansi.
Combined with UVA rays from the sun, chemicals compounds in calamansi (or limes) as well as other citrus fruits, celery, and more, can cause phytophotodermatitis, a skin reaction that can resemble splotchy sunburn with blisters in bad cases. And because many sunscreen formulas only protect against UVB rays, not UVA, your sunscreen won't necessarily protect you. It's why it's smart to wash your hands with soap right after squeezing citrus in your drink — even when you're staying indoors. And remember: Those UVA rays can pass right through window glass, so skin exposed to lime juice or other triggers can technically burn your skin even when you're indoors.
8. You use sunscreen—but leave your eyes exposed.
Even those who apply sunscreen religiously to the skin are vulnerable to corneal sunburn, also known as keratitis or colloquially as "sunburn of the eye". Large sunglasses can help protect you as long as they are their label explicitly says they protect against both UVA and UVB kinds of rays — not all do!
9. You use sunscreen—as long as makeup counts?!
So long as your tinted moisturizer or foundation has an SPF of 30 or higher, it's technically as good as the straight-up stuff. However, because few can pull off the 100-layer challenge IRL, most people don't apply nearly enough product for protection, leaving your skin even more vulnerable to sun rays. If you believe that less is more when it comes to makeup, stay safe by using a sheer, dedicated sunscreen underneath your makeup.
To that end, don't forget about your lips: Although you might not want sunscreen anywhere near your lips, they're still prone to sunburn, according to Dr. Ploch. It's why you should never leave your house without a lip balm containing at least SPF 30, then reapply often.
10. You use sunscreen—but you're on antibiotics.
Your meds may help you make a miraculous recovery, but they can also make your skin more prone to phototoxic dermatitis, an inflammatory skin condition that crops up within hours of sun exposure, and resembles sunburn. And sunscreen isn't always 100 percent effective in keeping your skin safe from harm. It's why Dr. Ploch warns people who are taking antibiotics to seek shade during the sun’s brightest hours, and wear a hat, sunglasses, and protective clothing (with UPF, or ultra violet ray protection factor, for extra credit).
11. You use sunscreen—but acne products too.
Because many products designed to keep acne under control are chemical exfoliants that thin the skin, they can make skin extra sensitive to sun, according to Dr. Ploch. If you're using acne products — even OTC stuff — you'd be smart to keep treated skin out of the sun, and even skip your regular routine when you know you'll be in sunshine all day, to be safe.
12. You use sunscreen—but you're on the pill.
While most birth control pills are not known to cause sun sensitivity, Dr. Ploch has heard some cases of skin reactions linked to the pill, which can lead to brown, blotchy spots on areas exposed to the sun. It's ever the more reason to take all the sun-protection precautions no matter what method of birth control you use.
Sunscreen use doesn't guarantee your skin is safe from sunburn: You've got to use the right stuff, apply it properly, and take additional precautions (???? ). If you do all those things and still end up with sunburn, try not to freak, then use these sunburn remedies to feel better, faster.
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.