Pinterest is a beauty-lover's dream: scan the Hair and Beauty category and you'll be met with gorgeous DIY curls and braids, easy nail art tutorials, and before-and-after shots that demonstrate the power of contouring. But you'll also find some tips and tricks that seem too good to be true—and really are, and even worse, can seriously damage to your skin. Here, Dendy Engelman, MD, a New York City-based dermatologic surgeon reveals the truth about three popular Pinterest beauty hacks.

Elmer's glue as a blackhead remover

Several viral Pins claim that if you coat your nose with Elmer's and let it dry, you'll be blackhead-free after you peel it off. And although we can't deny that it seems to work—Pinterest is full of gross before-and-after photos showing blackheads dotting the peeled glue—glue is not meant to be used on your skin, and can cause major damage. "The adhesive is too strong for the delicate skin around the nose or any facial skin," says Dr. Engelman. Pulling off the glue can cause broken capillaries, and since there's no DIY or over-the-counter treatment to erase them, you'll end up spending a pretty penny on laser treatments with a dermatologist.

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Using tape on your skin for precise makeup application

In trying to perfect an Amy Winehouse-level cat eye or cheekbones that rival Keira Knightley's, makeup artists have recommended using Scotch tape as an outline of where you should apply product. Dr. Engelman says there are two major problems with using tape around the eye area. First, the adhesive on the tape can cause inflammation of the eyelid—ouch. And second, the pull on the fragile periorbital skin can actually accelerate wrinkling. As for on the cheeks or anywhere else on the face, the pulling of the tape can stretch the skin over time, leading to sagging features—the opposite of a contour that's on point.

Using lemon on the skin to brighten dark spots

Sometimes the thought of a natural skin remedy sounds like the best option, especially when you happen to have it lying around in your pantry; seems safer, right? Not always. "I often joke that arsenic and cyanide are organic, but that doesn't mean they are good for us," says Dr. Engelman. She warns that although using lemon juice on dark spots can yield the desired results, it's often too caustic on the skin and you can get a chemical burn from the application. The pH of lemon juice, which is about 2, can be especially irritating to those with rosacea, eczema, or sensitive skin.