Even if our parents didn’t nag us about it, most of us know that we’re supposed to wear sunscreen, at least in the summer.

It can help prevent skin cancer by protecting us from the sun’s harmful ultraviolet rays, according to the American Academy of Dermatology (AAD).

learn about sunscreen

However, if we follow that advice and pick up a few tubes of sunscreen, we can be overwhelmed by all the options.

They have a variety of ingredients of which you may have heard conflicting things. You may be wondering which types of sunscreen are best for you and your family.

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Safety First

Let’s get one issue out of the way first: safety.

The AAD says that the use of sunscreen is not harmful.

“Current scientific data does not support claims that sunscreen ingredients are toxic or a hazard to human health,” according to the AAD. “Rather, evidence supports the benefits of applying sunscreen to minimize short- and long-term damage to the skin from UV radiation.”

However, Dr. Fiona Zwald, a dermatologist in Atlanta, noted there is one ingredient that it’s best to avoid. That’s the preservative PABA, which is no longer contained in most sunscreens.

She explained that “physical sunscreens” that contain zinc oxide or titanium oxide could be less likely to cause allergic reactions and are ideal for people with sensitive skin. They reflect light back off of the skin but can offer only a sun protection factor (SPF) of 50 or less.

Chemical sunscreens are the only ones available in higher SPF numbers.

Helioplex is a chemical agent that provides a broad-spectrum protection against ultraviolet A and B sun rays, she said.

“Not everyone can use chemical sunscreens because they can cause an irritation on the skin,” Zwald told Healthline.

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What About Kids and Sprays?

Zwald said that physical sunscreens are best for small children but chemical sunscreen and spray sunscreen should be avoided.

The AAD recommends avoiding exposing babies younger than 6 months to the sun’s rays, even with sunscreen on.

Broad-spectrum chemical sunscreens can be used on older children although physical sunscreens and those made for infants and toddlers can cause less irritation to their sensitive skin.

Overall, spray sunscreens should be used with caution on children. The Food and Drug Administration (FDA) is currently investigating the risks of accidental inhalation with their use.

You should avoid using spray sunscreen near the face or mouth, according to the AAD. When spraying it on children, be aware of the direction of the wind to avoid inhalation.

Spraying sunscreen onto your hands and then applying it can help you to avoid the fumes while ensuring adequate coverage.

Read More: Get the Facts on Skin Cancer »

Vitamin D and SPF Numbers

The AAD notes that using sunscreen may decrease your skin’s production of vitamin D.

It says that many people can get enough vitamin D from foods or supplements without increasing their risk of skin cancer.

What do the SPF numbers mean?

Once you’ve determined what type of sunscreen you want to buy, you’ll need to choose between various SPF ratings.

SPF 30 blocks 97 percent of the sun’s rays. While using a sunscreen with a higher SPF can block slightly more of the sun’s rays, no sunscreen can block all of them.

There is no scientific evidence that sunscreen with a higher SPF than 50 can protect you any better than one with an SPF of 50, according to the AAD.

It recommends that everyone use water-resistant sunscreen with an SPF of 30 or higher that provides broad-spectrum protection against UVA rays, which can prematurely age your skin, and UVB rays, which are the primary cause of sunburn.

Overall, people with paler skin will burn quicker when wearing lower number SPF sunscreens.

“The numbers are loose,” said Zwald.

Zwald, for example, has pale skin type and lives in Atlanta. If she uses a sunscreen with an SPF of 15, she’ll burn in 45 minutes.

“It’s not strong enough for me,” she said.

However, an SPF of 45 will give her around an hour and a half in the sun.

Read More: The 4 Best Vitamins for Your Skin »

Lather It On

Nevertheless, using a higher number SPF sunscreen does not allow you to spend more time outdoors without reapplying sunscreen.

All sunscreens should be reapplied after approximately two hours and after swimming and sweating, the AAD advises.

“Waterproof isn’t all that waterproof even if the label says its waterproof,” said Zwald. “You should probably reapply it. It’s not like waterproof mascara,” which stays on and eventually needs to be removed.

Zwald emphasized that reapplying sunscreen is especially important for those with pale skin or who are taking medication that makes their skin sensitive to the sun.

“Twenty-four hour sunscreen does not exist,” she said.

Read More: Melanin Protects From Skin Cancer but Can Also Cause It »

When to Use It

Skin care experts recommend using sunscreen all the time when you go outside, especially during the summer, regardless of your skin type.

Sunscreen can help prevent the damaging and aging effects of the sun, as well as skin cancer, even in darker skin types that tan more than burn, Zwald said.

She recommends applying it to the face over moisturizer, noting that she hasn’t seen a moisturizer with an SPF over 30. Tinted sunscreens also provide a good option, she said.

“The bottom line is that there is no one product,” she said. “You have to layer it.”

And don’t forget your lips. Skin cancer can form there. The AAD recommends using a lip balm or lipstick with an SPF of at least 30.

Applying it your face, however, can be easier than your back. The organization notes that the back is the most common site for melanoma, the deadliest form of skin cancer, and advises that you ask someone to help you apply sunscreen there.