Sunscreen advice: Dermatologists debunk myths

The muscular, tanned man says he has an important message from the “Sun God.”

“When you use sunscreen, you're literally denying yourself light exposure, which is the most important factor for your health,” she said in a TikTok video filmed on a Florida beach.

A man who goes by the handle “Captain Morgan” is part of an anti-sunscreen movement that claims sunscreen does more harm than good. Those behind the buzzword claim that chemicals in sunscreen can cause cancer and that sunscreen use causes vitamin D deficiency and weakens the immune system.

But dermatologists have warned against misinformation spread by the anti-sunscreen campaign, who say not wearing sunscreen actually causes cancer and other problems.

Debunking sunscreen myths

“What concerns me about this movement is that it's actually based on a lot of misinformation. There is no solid evidence that using sunscreen causes cancer,” Dr. Harvey Lui, a dermatologist and professor of dermatology and skin sciences at the University of British Columbia in Vancouver, said in a video interview with CTVNews.ca. “There's a huge amount of information accumulated over decades that confirms that the number one cause of skin cancer is ultraviolet radiation from exposure to the sun and artificial light.”

Dr. Linda Singh agreed, adding that sunscreens sold in Canada have been thoroughly tested and are safe.

“I think there's a lot of misinformation and fear-mongering out there in terms of chemicals harming our bodies,” the Oakville, Ont.-based dermatologist said in a separate video interview.

“Sun gods” and anti-sunscreen advocates argue that using sunscreen negates the benefits of exposure to the sun, but Louis said the sun's ultraviolet rays were harmful when they came into contact with the skin.

“These are the most energetic of the sun's rays. They are invisible to the naked eye and you can't really feel them,” Lui said. “And the energy of these UV rays is so intense that they can penetrate the skin and cause damage to DNA molecules.”

Lui said damage to DNA molecules can lead to abnormal cells in the skin, which can lead to skin cancer.

“UV light doesn't do much good,” he explained, “with the exception that it helps the skin make vitamin D.”

Responding to claims by anti-sunscreen campaigners, he said that while overuse of sunscreen could lead to a decrease in vitamin D, this would not be a problem for most people because vitamin D can be easily absorbed from foods such as oily fish and green vegetables, and from supplements.

And scientific studies have not shown that daily sunscreen use leads to vitamin D deficiency, Singh added.

As for people worried about chemicals in sunscreen, Louis said chemicals are everywhere, including in water and food, and they're not all bad.

He explained that the chemicals in sunscreen are actually beneficial because they block harmful UV rays.

Is it dangerous to not wear sunscreen?

Rather than backing up the claim that sunscreen is dangerous, doctors who spoke to CTVNews.ca said the opposite: not wearing sunscreen can be harmful.

Not wearing sunscreen is “very dangerous”, says Singh, who regularly treats facial skin cancer at his clinic: “People forget what the alternative is, which is that people are constantly dying from skin cancer caused by sunburn.”

Doctors say it's a good idea to wear sunscreen no matter how long you plan to be outside, and Louis likens it to wearing a seat belt: You might not end up needing it, but it's much safer to be on the safe side.

Louis said excessive exposure to UV rays can cause sunburn in the short term and increase the risk of skin cancer in the long term. Once you get a bad sunburn, your risk of developing skin cancer can double, he said.

While many people believe tanned skin looks healthier, tanning isn't actually an indicator of health — rather, it's a sign that your skin is damaged, says Louis.

“Tanning is your body's response to exposure to UV rays,” he says. “When you tan, your skin is saying, 'Hey, I don't like the UV rays hitting my skin, so I'm going to darken my skin and block the UV rays.'”

Additionally, UV rays can cause wrinkles, uneven pigmentation, and sagging skin.

“It makes your skin look older faster,” says Louis.

How to protect yourself from the sun

To prevent these problems, Louis recommends using sunscreen, seeking shade, wearing a wide-brimmed hat and covering up skin by wearing long-sleeved, tightly woven clothing or special UV-blocking clothing.

“A simple test is to hold the clothing up to the light, and if it's really almost opaque, then the UV rays can't penetrate very far to reach your skin and cause damage,” he explained.

To minimise sun damage, people should avoid being outdoors when the sun is at its strongest, he added.

How do you choose a sunscreen?

Lui said sunscreens are lotions or creams that contain filters that sit on the skin like a thin film that blocks UV rays from reaching skin cells.

Dermatologists say that any sunscreen, regardless of price or formula, is better than none.

Lui recommends choosing a broad-spectrum product that covers the different types of UV rays, known as UVA and UVB.

Choose a product with a sun protection factor (SPF) of at least 30.

SPF 30 means that if you wear sunscreen, your skin will stay in the sun for 30 times longer than if you don't.

“Higher is better,” says Louis.

Look for the Canadian Dermatology Association logo, which indicates the association has reviewed and endorsed the product, he said.

You can choose products that use mineral-based (or physical) sunscreens, sunscreens with organic filters (also known as chemical sunscreens), or both.

“The key is to use products that are comfortable to use, that feel good on your skin and that you're happy to apply, because the only sunscreen that works is the one you put on your skin,” he said.

How to apply sunscreen

Rather than smearing it all over your face, Louis recommends spreading it out in at least a pea-sized drop, or enough to leave a light film on your skin, and you can also do the same on other parts of your body that are exposed to the sun, like your neck and ears.

“And if you see just a little bit of white on your skin when you're done, it's probably thick enough,” he says. “Within a few minutes of applying the sunscreen, that white film will fade away.”

As long as you apply sunscreen correctly the first time, you shouldn't need to reapply it, unless you're going to sweat, swim or do other physical activity, he says.

However, sunscreen does wear off over the course of the day, so if you're spending a lot of time outdoors, Singh recommends reapplying it every two to three hours.

If you're using skin care products like serums, moisturizers, and makeup, it's best to apply sunscreen last, adds Xing.