Once upon a time, toothpaste was widely considered a great acne treatment and lemon juice was used for fading scars and discolouration. (Spoiler alert: Neither of these household staples should ever find their way onto your face.) Because the beauty industry relies so heavily on word of mouth and recommendations (that is, a product largely succeeds if people review it positively, either in real life or online), skincare myths and false information can spread more easily than they might be able to in other industries.

But thanks to the plethora of online beauty forums, consumers are becoming more knowledgeable about what they put on their skin, and the industry is adapting accordingly. For example, plastic microbeads, previously used in exfoliators for years, have been banned in Canada. Not only can they aggravate skin—causing small tears that make you prone to infections and breakouts—they’re awful for the environment. Because they’re so small, they aren’t caught by water filtration systems, and since they’re plastic, they don’t dissolve and instead just pile up in oceans, streams and lakes. Not good.

However, there are still plenty of misconceptions about what should and shouldn’t be used on skin. Below are five common skincare myths that somehow still persist—and we’re clearing them up, once and for all.

Myth: Coconut oil is a good facial moisturizer
“Coconut oil actually one of the most comedogenic oils,” says Dr. Linda Nguyen, Medical Director of Toronto’s 1Clinic, specializing in dermatology. That means it can clog pores and lead to pimples. “It’s thick and acts more like a wax when applied, sitting on top of the dermis and creating a plastic wrap-like film over pores—nothing gets in and nothing gets out,” she explains. If that mental image isn’t disturbing enough, what this does is prevent skin from properly doing its job of secreting oil and sweat. “Bacteria and dead cells fester under the skin, clogging pores, producing excess sebum and yes, causing breakouts,” says Dr. Nguyen.

Myth: Pore strips can help keep blackheads at bay
OK, while the process of peeling off a pore strip is understandably super satisfying, they often do more harm than good. “What they’re actually removing is hair, dead skin cells and sebaceous filaments—certainly not blackheads” [which live much deeper inside pores], explains Dr. Nguyen. With regular use of pore strips, skin’s protective barrier gets disrupted and you’re left vulnerable to skin irritations like redness, hives and dry patches.

Myth: Getting a “base tan” will ensure you don’t burn in the sun
The “base tan” myth, which claims that hitting up a tanning bed before heading somewhere tropical, can help ward off a sunburn, has been around for decades. And while it’s true that it does provide some protection, that protection is very minimal. Harvard Health Publishing, Harvard Medical School’s blog, explains that “going out in the sun with a base tan is equivalent to wearing a sunscreen with a sun protection factor (SPF) of 3 to 4.” So while it’s certainly better than nothing, these days we know that SPF 4 is nowhere near adequate sun protection, with most experts recommending a daily sunscreen with an SPF of at least 30. And what makes the base tan myth even more dangerous is that tanning beds are super bad for you. According to the Canadian Cancer Society, in 2009 the World Health Organization “upgraded the classification of UV-emitting devices, including tanning beds, from a probable carcinogen to a known carcinogen, meaning there is no doubt that indoor tanning causes cancer.” If that’s not enough reason to ditch the base tan myth for good, we don’t know what is.

Myth: You should apply sunscreen 15 to 30 minutes before going outside so it can “activate”
Stephen Alain Ko, more commonly known by his website and Instagram handle @kindofstephen, is cosmetic chemist who found internet fame by doing a Reddit AMA eight years ago. These days, he’s one of the most reputable online skincare experts around. The skincare myth he’d most like to clear up? The fact that you need to apply a chemical sunscreen 15 to 30 minutes before going outside to give it time to form a reaction with your skin and start working. “That’s completely untrue. If it were, we wouldn’t be able to measure UV absorption on plastic films, [which is] what is done in laboratory tests.”

Ko says he sees that advice repeated all the time, by both consumers and so-called “experts.” The truth about chemical sunscreens? They “should be applied 15 minutes before UV absorption so that they have time to dry and form an even film on skin,” explains Ko. “It’s a small, subtle difference, but it can [alleviate] negative consequences, like a fear of ‘chemicals.’” (Any good beauty editor will say this often, but once more for the people in the back: Everything is a chemical, even so-called natural ingredients!)

Myth: Your pores can open, close and change in size
Be honest: How many skincare products that promise to “shrink” pores are in your bathroom right now? The long-standing myth about being able to change pore size is a hard one to shake, but the truth is that pore size and visibility is largely genetic. Want Bella Hadid-level flawless skin? Unfortunately, you’ll need Bella Hadid’s genes. What about the common belief that heat (like steam, for instance) opens up pores and cold closes them? Michelle Wong, Chemistry PhD, high school science teacher, and the author behind the popular skincare blog, Lab Muffin, explains that “pores don’t open and close with heat and cold, since they aren’t controlled by muscle.” So while slight warmth can help ease oils out of congested pores, switching between extreme heat and extreme cold won’t do much more than irritate your skin.