The answer to this question is a many-splendored thing. To begin, we must admit that, like you, we love a product with a secret additional use? In today’s world of multitasking makeup, products that do double (or triple) duty are practically de rigeur—and since this saves us getting-ready time (and precious storage space), we couldn’t be happier to discover that our concealer is also a great eyeshadow primer, or our blush makes a great matte lipstick.

But there are some products out there that you really, really shouldn’t use in an alternate way, just because Pinterest tells you that you can. Many of these “beauty hacks” aren’t just disappointing—they’re downright dangerous. Here are 5 beauty products you should never multitask with.

Lipstick on eyes.
By now, we’ve all seen those “amazing makeup hacks” that promise to vanish your dark circles by covering them with orange or red lipstick—and Katy Perry says that she wears lipstick as eyeshadow all the time. So it has to be fantastic, right? Wrong. Not only does lipstick make a terrible concealer (it sinks into creases like crazy, for one thing), it can also damage your eyes. It’s true: red, orange and pink lipsticks (and liners) often contain carmine, an ingredient which can not only stain skin but can cause serious allergic reactions. We spend most of our time trying NOT to end up with red, itchy, watery eyes—so we’ll skip this, thanks.

Hair dye on brows.
Even though Pinterest may say that coloring your eyebrows with home hair dye is easy, it is actually incredibly dangerous. Dye, even carefully applied, can drip into your eyes and potentially blind you. The fumes can also irritate your eyes, and if you use too strong a developer, the dye can even burn off your brows. It’s not worth it. See a professional for all your brow-tinting needs, or use an amazing pencil to fill them in temporarily.

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