Many people assume that once sunscreen is applied, they’re fully protected from the sun’s rays. But if you’ve ever come home from a beach day with red, stinging skin despite using sunscreen, you’re not alone. According to the American Academy of Dermatology (AAD), most people don’t apply enough sunscreen or reapply as often as needed. Even the best SPF won’t work if it’s not used correctly—or if other factors are at play.
Here’s a closer look at why sunburn can still happen when you’re using sunscreen and how to make sure your skin gets the protection it deserves.
You’re Not Applying Enough Sunscreen
One of the most common mistakes is underapplication. The AAD recommends using about one ounce (a shot glass full) to cover all exposed skin on the body. Most people use only 25–50% of that amount, which means they’re getting far less protection than the SPF number on the bottle suggests.
For your face alone, aim for a nickel-sized amount of sunscreen. Remember areas that are easy to overlook—like your ears, tops of feet, back of the neck, and scalp.
You’re Missing Reapplication Windows
Even water-resistant sunscreens don’t last all day. Sunscreen should be reapplied every two hours, or immediately after swimming, sweating, or towel drying. A common misconception is that SPF 50+ lasts longer than SPF 30. In reality, both require reapplication at the same intervals—the higher SPF just blocks a slightly higher percentage of UVB rays.
If you’re outdoors for an extended time, keep a sunscreen mist or stick handy for quick touch-ups without disturbing makeup or clothing.
Your Sunscreen May Have Expired
Sunscreen doesn’t last forever. Over time, its active ingredients—especially chemical filters—can break down, making the product less effective. Check the expiration date before applying. If it’s been more than three years since you bought it, it’s time to replace it.
Heat and sunlight can also degrade sunscreen faster, so avoid leaving it in a hot car or in direct sun on the beach.
You’re Using the Wrong Type for Your Skin or Activity
Different situations call for different sunscreen formulas. If you’re swimming, sweating, or playing sports, you’ll need a water-resistant sunscreen labeled for either 40 or 80 minutes of protection.
For sensitive or acne-prone skin, mineral sunscreens (containing zinc oxide or titanium dioxide) are a great option—they sit on the skin’s surface and reflect UV rays rather than absorbing them. Chemical sunscreens, on the other hand, absorb UV rays and convert them into heat, which may irritate some skin types.
*The key is to find a sunscreen you’ll actually wear—and wear correctly.
You’re Relying Solely on Sunscreen
Even when used perfectly, sunscreen should be used as one part of a broader sun protection strategy. Dermatologists recommend pairing sunscreen with other methods, such as:
- Wearing protective clothing: Long sleeves, wide-brimmed hats, and UV-blocking sunglasses.
- Seeking shade: Especially between 10 a.m. and 4 p.m., when the sun’s rays are strongest.
- Using UPF-rated fabrics: Many modern shirts and swimsuits are designed to block up to 98% of UV radiation.
As Dr. Elizabeth Hale, a board-certified dermatologist and senior vice president of the Skin Cancer Foundation, says:
"Sunscreen is your last line of defense, not your only one."
You’re Forgetting to Apply Early Enough
Sunscreen doesn’t protect instantly. Chemical sunscreens need 15 to 30 minutes to fully absorb and create a protective barrier. If you apply right before stepping outside, your skin may still be vulnerable during those first few minutes of exposure.
Mineral sunscreens, however, start working immediately since they create a physical barrier on the skin’s surface—making them a better choice if you’re often on the go.
Environmental and Medication Factors
Certain medications (like antibiotics, acne treatments, or birth control pills) can make your skin more photosensitive, increasing your risk of burning even with sunscreen. The same goes for skincare ingredients such as retinoids, glycolic acid, or benzoyl peroxide.
Environmental conditions also play a role. Snow, sand, and water can reflect UV rays, intensifying sun exposure. Even on cloudy days, up to 80% of UV rays still reach the skin.
You’re Skipping Key Areas
Some of the most common spots for sunburn—like the tops of ears, back of hands, and scalp—are often missed entirely. Don’t forget to:
- Apply sunscreen on the backs of legs when wearing shorts.
- Use lip balm with SPF 30 or higher to protect lips.
- Apply scalp sunscreen spray or wear a hat if your hair is thin or parted.
Tips for Applying Sunscreen Properly
To make sure your sunscreen is doing its job:
1. Apply 15–30 minutes before sun exposure.
2. Use enough: One ounce for the body, nickel-sized for the face.
3. Reapply every two hours.
4. Cover all exposed areas.
5. Combine with shade, clothing, and hats.
*Consistency is key—think of sunscreen as a daily habit, not just a beach-day essential.
If you’re getting sunburned despite wearing sunscreen, it’s not always the product’s fault. More often, it comes down to how and when you’re applying it—or forgetting to reapply altogether. By using enough, choosing the right formula, and taking a few extra precautions, you can significantly reduce your risk of burns and long-term skin damage.
After all, sunscreen isn’t just about avoiding sunburn—it’s about maintaining healthy, resilient skin for years to come.
Image credit: Shisuka via Canva Pro
