Sunscreen vs. Sunblock: What's the Difference, and Which One Is Better?

If you take only one thing to the beach, it has to be sun protection. But when you stop by the drugstore to stock up and start reading product labels, you notice that there are two types: sunscreen and sunblock.

The big difference between the two is how they work. Here, Health has decoded the fine print between sunscreen and sunblock and unraveled the benefits and drawbacks of each to help inform your choice the next time you're shopping for sun protection.

Sunscreen vs. Sunblock: The Basics

Sunscreen and sunblock don't work in the same way, but they both protect the skin from harmful ultraviolet (UV) rays. Sunblock is so named because it literally blocks UV rays by forming a physical shield, while sunscreen absorbs UV rays before your skin can.

In this article, the word sunscreen is used to refer to chemical sunscreens, those containing chemicals that absorb the sun's rays before they hit your skin. If the active ingredient is oxybenzone, avobenzone, octisalate, octocrylene, homosalate, or octinoxate, you've got a (chemical) sunscreen. You can also recognize these products because they're relatively easy to rub into the skin and don't leave a white residue.

Technically called physical sunscreens, sunblocks don't work in the same way as their chemical counterparts. The active ingredients in sunblock are usually zinc oxide or titanium dioxide. Instead of absorbing the sun's rays, sunblocks shield you from the sun by deflecting the sun's rays.

Sunscreen and sunblock also have different application methods. Because sunscreen only works when it's absorbed by the skin, it needs to be rubbed in. However, you can simply slather sunblock on, since it acts as a physical barrier.

You do have to apply sunblock evenly, though: UV light can hit any exposed parts of the skin, no matter how small. Because sunblock isn't rubbed in, it normally leaves a white cast on the skin, while sunscreen disappears completely.

Even though they don't work in the same way, sunscreen and sunblock both protect you from harmful damage, whether from sunburn, sun poisoning, or skin cancer.

Side Effects of Sunscreen and Sunblock

If used correctly, the side effects of sunscreen should be minimal. It's important to choose the right product for your skin type, particularly if you have sensitive skin.

"Just as with anything applied to the skin, there is the chance of irritation or skin reaction," Connecticut-based dermatologist Rhonda Q. Klein, MD, told Health.

Irritant contact dermatitis is one type of reaction when the skin becomes inflamed or irritated after you apply sunscreen. However, it's not the only reaction that can occur.

"Some sunscreens contain oil and can cause acne," Deborah Jaliman, MD, a dermatologist in New York City, told Health. "If you have very sensitive skin, others might sting or cause itching."

Is Sunscreen or Sunblock Better?

Both types of sun protection have their pros and cons. Sunscreens don't leave a white residue, but some of the ingredients may be irritating to the skin.

Dr. Klein gives sunblock the edge because it doesn't have any chemical ingredients that can cause irritation. In fact, she explained, sunblock is "well-tolerated by even the most sensitive skin types," explained Dr. Klein.

Ultimately, the best sun protection product is the one you like to use and works for your needs. Still, whether you pick sunscreen or sunblock, there are some general things to keep in mind.

All sunscreens and sunblocks come with an SPF (sun protection factor). The American Academy of Dermatology advises using an SPF of at least 30, which blocks 97% of UVB rays.

Higher SPF numbers block a little more of the sun's UVB rays than lower ones. Still, no sunscreen can block 100% of them.

UVB rays are one type of UV light that can cause skin cancer—the other is UVA. UVB is associated with sunburns, while UVA is associated with tanning and skin aging.

UVA was once thought to be safe, but we now know it's not. It can go through windows and clouds, and it's the light used in most tanning beds. UVA goes deeper into the skin than UVB and can also lead to skin cancer. Sun protection products now have ingredients to protect you from the broad spectrum of UVA and UVB rays.

Recommendations and Tips

To get the most out of your sunscreen or sunblock, make sure the product has these three qualities:

• Broad-spectrum protection (guards against UVA and UVB rays)
• SPF 30 or higher
• Water resistance

Remember to pick a sunscreen or sunblock that you like so that you keep using it. Sunscreen and sunblock may come in various forms, including lotions, gels, creams, ointments, wax sticks, and sprays.

Use creams on dry skin and your face. Sticks make it easy to apply sun protection around your eye without getting product in your eye. Gels work great for hairy areas, like your scalp.

When applying sunscreen or sunblock, cover all of your skin that clothing doesn't cover—and don't forget the tops of your feet, your neck, your ears, and the top of your head.

In addition to following the directions on the bottle, apply sunscreen and sunblock 15 minutes before going outside and every two hours after that. Also, reapply after swimming or sweating because water will wash off your protection.

Use sunscreen all year round. UV rays can still harm your skin even on cloudy days. Clouds aren't great protection from the sun because they still allow about 80% of the UV rays to get through. Also be diligent about applying sunscreen when you're around snow, water, or sand because these substances reflect the sun's rays.