When you find a product that makes you look and feel really good, it’s pretty much the best day ever. When you find a bargain that delivers results? It’s time to make room in your bathroom for backups.

The latest multitasking marvel making waves in the drugstore aisles is the L'Oréal Paris Revitalift Derm Intensives 10% Glycolic Acid. Its star ingredient, glycolic acid, isn’t new, per se. What is: The formulation, and that you can now get the all-time derm fave without any of the guilt associated with a cart full of skincare splurges.

But before we get to the formulation, it’s worth hyping glycolic acid for a sec. It famously evens out skin tone, lightens dark spots, smooths fine lines, and generally makes you look like you’re BFF with the top facialist in town.

“It’s a big ingredient in higher-end skincare because it’s so effective,” says Devika Icecreamwala, M.D., a dermatologist in Berkeley, California. “After using it for a few weeks, you notice skin feels softer and more even and glowy, and it’s been proven in clinical studies to lighten melasma and brown spots.”

The alpha hydroxy acid works by breaking down the glue that holds dead skin cells together and to the surface of your skin, including the abnormally pigmented ones, she says. So when those cells slough off, the healthier, smoother, and more even-toned skin underneath shines through. What’s so cool, though, is that this serum gives you 10-freaking-percent glycolic acid, which is among the highest levels allowed in standard OTC topicals, Dr. Icecreamwala says.

Now, onto the formula. It contains ingredients like aloe, glycerin, and hyaluronic acid, which hydrate and calm skin while the glycolic acid does its thing. They essentially help balance its potent exfoliating power. That’s important because glycolic acid is no joke—that’s why it’s used in derm-strength peels. It has the potential to make skin red or sensitive at high concentrations.

But the added skin-soothers give you the benefits while minimizing the risk of redness or irritation, says Joshua Zeichner, M.D., Director of Cosmetic & Clinical Research in Dermatology at Mount Sinai Hospital in New York City and member of the L'Oréal Paris advisory board. However, any formulation of glycolic acid will sensitize skin to the sun, so only use it at night and always wear sunscreen during the day—even in the winter.

Bottom line: This serum is top-shelf quality. But don’t take our word for it. L'Oréal Paris commissioned independent clinical trials, and the results showed that not only did skin feel immediately smoother after use, it also looked younger after one week. After two weeks, dark spots appeared less noticeable; after four, wrinkles and fine lines were visibly reduced.

“To get a high-quality glycolic product, you really don’t have to spend a lot of money,” Dr. Zeichner says. “The key is choosing a trusted brand and products rooted in science that have been clinically tested.”