What types of sunscreens are there?

The two major types of sunscreen are chemical and mineral (or physical) sunscreen. Both are used to prevent sunburn and other skin damage from UV radiation, but do so in different ways.

According to Raman Madan, chief of dermatology at Glen Cove Hospital, chemical sunscreens have active ingredients that sink into your skin and absorb UV rays "like a sponge." In the United States, common chemicals used in sunscreen include homosalate, oxybenzone, avobenzone, octinoxate, octisalate, and octocrylene.

On the other hand, mineral sunscreens use ingredients like titanium dioxide and zinc oxide to create a physical barrier that sits on top of your skin and reflects UV light.

Are chemical or mineral sunscreens better?

According to Ducharme, many people tend to prefer using chemical sunscreens since mineral ones can leave a chalky white residue on the skin.

However, Abel Torres, chair of the dermatology department at the University of Florida College of Medicine, said mineral sunscreens generally last longer than chemical ones and that the residue is a sign of their staying power.

"If you know you're going to be on the beach for a long time, mineral may be a better choice because you won't have to worry about having to reapply it as much," Torres said.

People with acne-prone or sensitive skin may also do better with a mineral sunscreen. Research suggests that the zinc in mineral sunscreens can help clear blemishes. Madan also noted that since mineral sunscreens don't sink deeply into the skin, "it's almost impossible to be allergic" to them.

Some research has also suggested potential safety risks with chemical sunscreens. For example, a recent study found that ingredients used in chemical sunscreens enter the bloodstream after being absorbed into the skin. Other studies suggest that sunscreen chemicals like oxybenzone may be associated with increased risks of certain cancers and hormone disruption.

However, Torres emphasized that these studies only hint at potential risks of chemical sunscreens and have not proven they are dangerous. So far, there's not enough information to tell how chemical sunscreens impact people's health.

There are also known benefits of wearing sunscreen, either chemical or mineral, so "if chemical formulas are the ones you'll actually use, it's better to choose those than to go out unprotected," Ducharme writes.

What SPF should you use?

SPF, or sun protection factors, measures how much UV radiation it will take to burn your skin with sunscreen on compared to not wearing any sunscreen at all. The higher SPF a sunscreen has, the more protection it'll offer.

Currently, FDA recommends people use a sunscreen with an SPF of at least 15, while the American Academy of Dermatology recommends using a sunscreen with an SPF of 30 or higher. People with fair skin may also benefit from using sunscreens with higher SPFs.

However, choosing the highest SPF possible may not be as beneficial as you think. According to Madan, SPF values begin to offer diminishing returns after a certain point. A sunscreen with an SPF of 50 offers such strong protection that upgrading to an SPF of 100 will only offer a tiny amount of additional protection.

But regardless of which SPF you choose, it's important to reapply your sunscreen after a couple of hours, especially if you've been sweating heavily or swimming. The Skin Cancer Foundation also recommends choosing sunscreens that are labeled with "broad-spectrum protection." These sunscreens offer protection for both UVA rays, which cause wrinkles and skin aging, and UVB rays, which cause sunburns. Both types of UV rays are associated with skin cancer.

What form of sunscreen is the best?

Sunscreen comes in several different forms, including sprays, sticks, and powders, but Madan recommends using a cream or lotion version when possible. "It goes onto the skin a little bit thicker, so patients get more coverage out of a lotion," he said.

Research also suggests that cream sunscreens are more effective than aerosol ones. Studies have found that people often don't use enough sunscreen with aerosol products since propellants and other ingredients dilute the formulas. People may also inhale potentially harmful substances when using an aerosol spray, particularly if they're applying sunscreen to their face.

One type of sunscreen Madan said he would avoid is powdered sunscreen since FDA has said it needs more data to prove it is effective like other types of sunscreen. In general, any kind of sunscreen is better than none, so use what you have on hand to protect yourself from the sun. (Ducharme, TIME, 5/9)

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