Everyone warned me before I first started using the iconic beauty product Biologique Recherche P50 ($67) that it had… a smell. As soon as I swiped the acid toner all over my face, the aroma hit my nose, and I had to remind myself that it’s a holy-grail product for a reason. I kept on slathering and in no time, I too, could see why everyone clamored for it. Now, I associate the smell with a radiant complexion and winding down at nighttime.

In the beauty world, a stinky scent is no reason to be deterred, though. P50, SkinMedica TNS Serum ($281), and SkinCeuticals CE Ferulic Serum ($166), for instance, all have scents that are left of center. “I can totally understand why people would shy away from skin-care products that smell unpleasant,” says Shirley Chi, MD, a Los Angeles-based dermatologist. “But that being said, there are many reasons to work through this. Some of the most effective anti-aging treatments out there smell.”

“Some of the most effective anti-aging treatments out there smell.” —Dr. Shirley Chi

Angelina Umansky, star facialist and founder of Spa Radiance, agrees, noting that her spa’s top sellers are these three aforementioned beauty products “because they perform,” she tells me. “These brands formulate to give consumers results. Period.”

And results are what you get when you slather on these star beauty products. For example, that TNS Serum? It’s got human-growth factor in it. “SkinMedica TNS is one of the most popular post-treatment products at our medical spa because of its active ingredient,” says Umansky. “P50 can literally change skin—it’s definitely a holy grail product that none of my clients can live without. Patients care more about how TNS speeds up the healing process after treatments like microneedling and chemical peels than how it smells.” And despite the fact that the smell of Skinceuticals CE Ferulic is frequently compared to that of hot dog water, it neutralizes free radicals to prevent all sorts of bad things from happening to your complexion with a dose of antioxidants. “That’s what makes it smell metallic—it’s used to stabilize the compound of vitamins,” says Dr. Chi.

So, just why does this happen? “Anything that has a nitrogen structure will smell,” explains cosmetic chemist Perry Romanowski. “The smelliest ingredients are probably lanolin and its derivatives, but shea butter can also smell, as can amino acids, algae extracts, and other plant extracts.” The reason you don’t often detect this in products is because they’re covered up by fragrances to hide the scents. In fact, even “unscented” products often contain “masking fragrances” to make them smell neutral (hot tip: because of this, if you’re truly looking for something devoid of fragrance, make sure your package says “fragrance-free”). “Some skin-care products do use masking fragrances in order to mask the base odor,” says Ginger King, a cosmetic chemist.

Brands with “stinky” beauty products—like those mentioned above—purposefully do not use these masking ingredients or they use fragrance at low levels in the formula, which doesn’t completely neutralize the initial scent. “Biologique Recherche never formulates products with synthetic fragrances,” says Philippe Allouche, MD, head of creation and co-owner of Biologique Recherche. “We want to ensure we preserve the integrity of the formulas and try to avoid sensitization phenomena.” And so, since lots of their ingredients are pure and raw marine or botanical extracts they often have a distinct, strong smell. “That’s due to the high concentrations of active ingredients, with nothing added to mask the smell,” says Dr. Allouche.

While sensory experiences, like scent, can be impactful when selecting a beauty product, don’t make that the only consideration. Many of the cult-favorite products on the market don’t have stereotypical fruity or floral scents, but they work, and when it comes to skin care, results that you can see win out every time.

Another thing to get straight is the fact that you don’t have to feel your skin care tingling to know that it’s working. And this is what to know about algae in skin care, which smells not so great but makes your skin look fab.