Benefits & Limits: What Sunscreen Really Does and Doesn’t Do

3 Key Points:

1. Sunscreen protects against sunburn, skin cancer, and premature aging, but not 100% of UV rays.
2. It must be reapplied regularly and doesn’t last forever, especially after swimming or sweating.
3. Sunscreen should be part of a broader sun protection routine, including shade, clothing, and sunglasses.

While anti-aging ingredients like peptides, retinol, and vitamin C are praised for their ability to improve signs of aging, one product stands out as a more effective defense against premature aging: sunscreen.

Mentioned actives can help reduce lines, wrinkles, and dark spots, but sunscreen protects against sun damage, the main cause of premature aging or photoaging. That’s why many experts agree: if you’re going to prioritize just one anti-aging product in your routine, make it sunscreen.

But do you really know what sunscreen does and doesn’t do? It’s a powerful defense against UV rays, but not a magical shield. Understanding its benefits and limitations can help you make smart choices when it comes to protecting your skin.

What Sunscreen DOES 

Protects against sunburn

Both UVA and UVB rays contribute to skin damage, but UVB rays are more readily absorbed by the skin’s outer layer and are the primary cause of sunburn. Broad-spectrum sunscreens are formulated to protect against both, helping to prevent the redness and inflammation associated with sunburn.

It’s also important to understand that tanning is a form of skin damage. There’s no such thing as a safe tan. Even a “healthy glow” indicates harm to DNA, increasing the risk of premature aging and skin cancer. And contrary to popular belief, a tan does not protect you from sunburn or further UV damage.

Reduces skin cancer risk

UV radiation from both UVA and UVB rays can penetrate the skin and damage the DNA of skin cells, potentially leading to cancerous mutations. Broad-spectrum sunscreens help by absorbing or blocking this radiation before it can harm the skin. This reduces the risk of sunburn, premature aging, and most importantly, skin cancer.

Daily sunscreen use is a vital part of skin cancer prevention. For effective protection, apply a broad-spectrum sunscreen with SPF 30 or higher every day, even when it’s cloudy. Don’t forget to reapply every two hours, especially after swimming or sweating.

Prevents premature aging

While UVB rays are responsible for sunburn, UVA rays are the primary cause of premature skin aging, also known as photoaging. UVA penetrates deeper into the skin, damaging collagen and elastin fibers, which are important for skin’s firmness and elasticity. Over time, this leads to wrinkles, sagging, and a dull or aged appearance.

At Dr. Sylvia Skin Care, we offer two sunscreens that help protect the skin:

• Sunshield SPF 45 – A lightweight, non-greasy sunscreen offering broad-spectrum protection. It is formulated with ingredients that nourish, hydrate, and soothe the skin, making it ideal for sensitive skin.
• Sheer Defense Tinted SPF 46 – A universally tinted formula that protects against UVA, UVB, and infrared radiation. It’s fast-absorbing, packed with antioxidants, and contains niacinamide to help reduce redness and even out skin tone.

Minimizes sun damage

Beyond burns and wrinkles, UV exposure can damage skin cells at a cellular level, weakening your skin’s structure over time. Sunscreen helps minimize this damage by acting as a protective barrier that reflects or absorbs UV rays. This can then help prevent sunburn, premature aging, and reduce the risk of skin cancer. 

Sunscreens contain ingredients that either absorb or reflect UV radiation, preventing it from reaching the deeper layers of the skin. And by doing so, they also help prevent the breakdown of collagen and elastin, which can slow down skin aging. 

What Sunscreen DOESN’T Do

While quality sunscreens are essential, they can’t provide complete sun protection on their own. Here’s what they can’t do:

Provide 100% protection

Even sunscreens with the highest SPF don’t block all UV rays. Also, higher SPF numbers don’t translate to more protection, and relying solely on it can be misleading. For example, SPF 30 blocks about 97% of UVB rays, while SPF 50 blocks around 98%. That small difference may seem minor, but can add up with prolonged exposure.

It’s also important to remember that SPF only measures protection against UVB rays. UVA rays, which contribute to deeper damage and premature aging, aren’t reflected in SPF ratings. That’s why choosing a broad-spectrum sunscreen is important. This indicates they offer protection against both UVA and UVB rays. 

Last forever

Like any skincare product, sunscreen breaks down over time and loses effectiveness. Water, sweat, and towel-drying can wash away or dilute sunscreen, which is why it is essential to reapply every two hours, especially after swimming or sweating.

Also, always check the expiration date before use, as expired sunscreen may not provide adequate protection.

• The active ingredients in the formula can degrade over time, making the product less potent.
• Expired sunscreens can change in texture, smell, color, and consistency, making them difficult to apply evenly/properly. 
• Heat and sunlight exposure can also degrade sunscreen, even before the expiration date. Make sure to store it in a cool, dry place away from direct sunlight and extreme temperatures.

Make you immune to sun damage

Wearing broad-spectrum sunscreen doesn’t give you a free pass to spend unlimited time in the sun. As previously mentioned, sweat, water, and time gradually wear off the protective layer, so reapplication is essential. 

Additionally, most of us don’t apply enough sunscreen or miss certain areas, leaving those vulnerable to UV damage. Applying sunscreen too thinly also means less protection than the labeled SPF provides. Remember, even the best sunscreen can’t shield your skin if it’s not applied properly and generously.

For further reading: Less Effective Sunscreen? Stop Doing These Things When Applying SPF

Replace other sun protection

Sunscreen is only one part of smart sun safety. For full protection, remember the 5 ‘S’s of Sun Safety. 

• Slip on clothing – Wear long sleeves and tightly woven fabrics that cover as much skin as possible.

• Slop on sunscreen – Apply broad-spectrum SPF 30+ sunscreen. Reapply every 2 hours, especially after swimming or sweating.

• Slap on a hat – Wear a wide-brimmed hat to protect your face, neck, and ears.

• Seek shade – Avoid direct sun exposure, especially between 10 a.m. and 4 p.m. Use trees, umbrellas, or stroller shades for cover.

• Slide on sunglasses – Wear sunglasses with 100% UV protection to protect your eyes from sun damage.

Prevent all skin damage

While proper sunscreen use significantly reduces skin damage, it can’t eliminate it entirely. UV rays can still cause subtle, long-term effects even with protection, which is why a multi-layered approach to sun safety is essential.

UVA rays, which make up the majority of UV radiation reaching the Earth, are present year-round. They can also penetrate glass, which means that even indoor exposure contributes to damage. Repeated UVA exposure leads to wrinkles, fine lines, uneven tone, and age spots. Regular sunscreen use helps slow these effects, supporting smoother, more youthful skin over time.

Sunscreen is a powerful tool, but only when used correctly and consistently. Make it a daily habit: apply generously, reapply often, and combine it with other sun protection measures. If you’re concerned about photoaging or premature skin damage, schedule a consultation with one of our aesthetic doctors in Singapore for personalized care.