It's no secret that YouTube has changed the beauty world forever.

From new products to how to master professional techniques, YouTube is increasingly where people turn to for their beauty advice.

But not all the advice YouTubers give is so good — sometimes it's downright dangerous.

Here are 11 times YouTubers gave absolutely catastrophic beauty advice... and maybe you didn't even know it.

1. Lip scrub as face scrub.

THE CRIME: Telling fans that his boyfriend had used JSC Marshmallow Lip Scrub on half his face, and "never looked so smooth."

THE EVIDENCE: Jeffree Star's Velour Lip Scrubs are fine to exfoliate your lips, but NOT the entirety of your face. Sucrose is listed as the first ingredient, and anyone who has used these knows that they're made primarily of rough, scrubby sugar particles.

Sugar is one of those ingredients that shows up way too often on DIY lists, but shouldn't. The particles in sugar are far too rough for the thinner, generally more delicate skin on your face — it can cause small abrasions, and something scary called "micro-tears." This can lead to breakouts and irritation — definitely not what you want.

THE VERDICT: You're far better off using a chemical exfoliant, or a more gentle physical exfoliant... like a washcloth.

2. Wasabi as a 2-minute pimple cure.

A post shared by Farah D (@farahdhukai) on

THE CRIME: Farah Dhukai, DIY queen of Instagram, claims that wasabi will vanish a pimple in two minutes.

THE EVIDENCE: There is literally no evidence that wasabi does anything to skin besides irritate it. At the time Farah's video was going viral, I reached out to my dermatologist, Dr. Estee Williams, to see if I was missing something about this DIY treatment. "I always say that it's essential for doctors in the 21st century to keep an open mind, especially in the aesthetic practice of dermatology, where patients crowdsource tips for all things skin," she told me. "But it is a physician's obligation to make recommendations based on rigorous scientific data, that are effective and safe. Wasabi has the potential to cause more harm than good, and I do not believe it is effective at clearing up whiteheads in 2 minutes."

THE VERDICT: This "wasabi hack" is still really bad advice. But don't just listen to me — listen to Dr. Williams, who I trust with my own face. I asked her if it possible for anything — medical, over the counter, DIY — to get rid of a pimple in two minutes, with no redness afterwards, as Farah appears to demonstrate in her video.

"Not without magic," she said. "The same way it takes time for the body to develop growths, lesions, rashes, etc., it takes time for them to heal.  I cannot think of anything topical that would work on a pimple in two minutes."

3. Red lipstick to hide dark circles.

THE CRIME: Vlogger Deepica Mutyala shot to fame after she showed the world an "easy" hack to hide dark circles — by color-correcting with red lipstick.

THE EVIDENCE: While color-correcting is awesome, using red lipstick under your eyes is not a good idea. Lipsticks are not formulated to be eye safe, and red lipsticks SPECIFICALLY often have certain pigments and dyes that can irritate your looking-balls. And that's not even touching the fact that putting used lipstick by your eyes can easily transfer bacteria — yuck.

THE VERDICT: Remember: "If it's safe for eyes, it's safe for lips — but if it' safe for lips, it's not necessarily safe for eyes." Just use a color-correcting palette that's guaranteed safe.

4. Lemon juice for ~perfect~ skin.

kendall jenner bad skincare advice
photo: Kendall Jenner / Instagram

THE CRIME: In a "KenDIY" section on her website, Kendall said that a mask made of an egg white and the juice of half a lemon is all you need for ~flawless~ pH-balanced skin. In fact, she credited the DIY with clearing her acne completely.

THE EVIDENCE: You should never, ever put lemon juice on your face! Ever! It is terrible for your skin! To quote myself:

"Lemons are full of citric acid, which will nuke the top layer of your skin. As anyone who ever put lemon juice in their hair knows, citric acid is also photosensitive — meaning it reacts with the sun. On your skin, this can lead to discoloration and dark spots... which is pretty much what you're trying to get rid of."

And if you have acne-prone skin, which Kendall does, it's even worse — not only does lemon juice, an acid, not balance pH, if it gets into any healing blemishes, it will irritate them.

THE VERDICT: Kendall, who suffered such horrific acne that it affected her self-esteem, cleared up her skin with the help of one of the best dermatologists in the world, Dr. Christine Kidd. Even with her doctor's professional help, it took several years (Kendall's words) for her skin to clear up. She now relies on extremely expensive laser treatments to keep her complexion perfect. And this isn't something I need to speculate about — Kendall talked about all of this on her website, in a post that has, mysteriously, been deleted.

Seems like Kendall has one set of advice for readers of her site, and one that she follows herself.

5. Liquid lipstick as eyeliner.

THE CRIME: Using liquid lipstick as liquid eyeliner. While Clawdeena9 didn't invent this trick, this video is one of the most watched on all of YouTube.

THE EVIDENCE: Once again — just because a product is safe for your lips, it's not always safe for your eyes. Liquid lipsticks can contain dyes and additives that make them not safe for yer peepers.

And AGAIN again, cross-contamination is a real thing! If you're using a liquid lipstick that has touched your lips on your eyes, you may be spreading bacteria from one place to another. This can lead to eye infections, and is generally really gross.

THE VERDICT: There are so many colorful, awesome liquid liners out there now — use one of them instead.

6. Dental flossers and Listerine to extract whiteheads and blackheads.

THE CRIME: Instagram star Sukhi Mann used flossers to "extract whiteheads and blackheads," then a cotton ball soaked in Listerine as toner.

THE EVIDENCE: According to dermatologist Dr. Ava Shamban, the problem here isn't exactly the flossers — even though since they're not sterile, they could potentially smear pimple bacteria all over your face. No, the BIG problem is the Listerine. She told Glamour that if your chosen mouthwash-toner has menthol in it, "it could cause contact dermatitis, which is an allergic reaction."

THE VERDICT: Don't use mouthwash as toner. Also, don't extract your blackheads and whiteheads if you're not a dermatologist.

7. Toothpaste to cure pimples.

THE CRIME: Since time immemorial, or at least since I was a kid reading ladymags, we've been told the toothpaste makes an excellent spot treatment for pimples. This advice has, naturally, spread to YouTube — despite being very bad.

THE EVIDENCE: Apparently back in the day, most toothpastes contained an ingredient called triclosan, an antibacterial which was A) controversial, and B) not even in most toothpastes today. Triclosan was previously used to kill acne-causing bacteria, which is how this hack seems to have gotten legs — but since toothpastes would only contain a teeny amount of it, plus a LOT of ingredients that may make skin really red and dry, it's not worth it.

THE VERDICT: Nah.

8. Lemon juice for perfect skin, part 2.

kandee johnson skincare
photo: Kandee Johnson / Instagram

THE CRIME: Kandee Johnson is as known for her beautiful skin as her positive attitude. But back in the early days of her channel, Kandee made a video extolling the virtues of lemon juice for your skin.

THE EVIDENCE: Calling herself "The Skin Doctor," Kandee explains why lemons, rubbed straight on your skin, will help "remove dead skin cells" and help with "acne, discoloration, sun spots, freckles, and age spots... all kinds of things that you don't want."

Kandee mixed lemon juice with sugar (!!!) to make an exfoliating scrub, and... just NO. As mentioned, lemon juice contains acid which can scorch the heck out of your skin. It can also react weirdly with the sun, leaving dark patches behind. Additionally, here's straight up sugar again causing micro-tears and possibly aggravating your complexion. Please don't do this.

THE VERDICT: Six million people have watched this. That's six million people who may have hurt themselves on Kandee's say-so. They deserve better.

9. Homemade sunscreen.

THE CRIME: DIY sunscreen made from coconut oil, zinc oxide, beeswax, and olive oil.

THE EVIDENCE: Zinc oxide is a physical sunscreen, so that would provide some UV protection — but professionally-made sunscreen is blended with multiple other ingredients to provide maximum protection. There's no way to tell the SPF rating of a homemade concoction like this — the video indicates it's an SPF 20, but how do you know? — so you don't know how often to reapply. Not to mention many people with acne-prone or sensitive skin shouldn't use a lot of coconut oil, as it can clog pores.

THE VERDICT: Don't make your own sunscreen. UV damage is real, skin cancer is real, do not take risks with that stuff.

10. Beard dye to color brows.

THE CRIME: Using men's beard dye to color your brows.

THE EVIDENCE: Beard dye is often permanent hair color — and let me scream this from the mountaintops, THIS SHOULD NOT BE USED NEAR YOUR EYES. Permanent dyes require a process called oxidation to open the hair's cuticle and deposit the color — which is super flipping dangerous anywhere near your eyeballs. There's a reason any permanent dye comes with a "do a patch test" warning — they can cause allergic reaction, skin irritation, and BLINDNESS.

THE VERDICT: Use a brow pencil. It's not worth risking it all.

11. Cotton wool lash extensions.

THE CRIME: Huda Kattan used fibers she pulled out of cotton balls as lash extensions, and guys, I'm tired.

THE EVIDENCE: Cotton wool is made up of long, thick fibers. Unlike the lil fibers found in extending mascaras, if cotton wool gets in your eyeballs, it can REALLY cause redness and eye irritation... or worse.

THE VERDICT: Do I have to say it? I think I have to still say it — don't put stuff that isn't specifically for your eyes on your eyes.