The whole point of using beauty products is to feel good. It’s why things like sheet masks, face oils, and fancy serums exist in the first place. But every once in a while, beauty products backfire, and instead of being left with smooth skin, you wind up with an allergic reaction on your face. Yikes.

In the same way you can be allergic to the ingredients on a restaurant menu, you can also be allergic to the ingredients in your favorite serums and moisturizers. “When you’re allergic to a skin-care product, your skin may become red and flaky—particularly around the eyelids,” says New York City-based Adarsh Vijay Mudgil, MD, medical director of Mudgil Dermatology.

It’s also worth noting that there are two different types of reactions that can occur from your products: Allergic reactions and irritant ones. “An allergen is something your immune system recognizes and has a response to,” says Austin-based dermatologist Ted Lain, MD. “An irritant dries out your skin too much or allows your skin to lose too much hydration. It can look like an allergy, but usually it takes a few days of using something for an irritant dermatitis to occur, whereas an allergy will occur fairly quickly after the first or second application.”

Creating an exhaustive list of every allergen and irritant that may be lurking in your labels would essentially be the same as typing up every ingredient on the back of a beauty label. There are hundreds of chemicals in cosmetics that could cause a reaction (“natural” ingredients among them), but there are a few common culprits that tend to pop up more regularly. “It’s best to use products that are hypoallergenic, fragrance free, and dye free,” says Purvi Parikh, MD, an allergist and immunologist with the Allergy and Asthma Network. “If you’re having frequent reactions despite switching products, I recommend patch testing by a board certified allergist or dermatologist so you know what to avoid.” Keep scrolling for common allergens and irritants and what to do about them.

Watch out for these ingredients on your beauty product label

Preservatives: Preservatives are key because the keep your beauty products from going bad, but for those with sensitive skin, they could be a culprit in causing a skin rash to flare up.”Pretty much every skin care product needs a preservative, especially if there’s water in it because you can get mold very, very easily,” says Dr. Lain. “So these preservatives are super important, but you can have an allergy to them, so that would be something I would be concerned about as well.” There are many ingredients that brands tap to preserve ingredients. Commonly, they come at the back end of an ingredient label, so while it may take some Googling to figure out what the formula consists of that might be irritating your skin, pay attention to the ingredients keeping your formula fresh.

Fragrance and essential oils: There’s a reason why dermatologists say they wouldn’t use products with fragrance in them. Heavily scented products can trigger allergic reactions in the skin, leading to rashes and irritations—two things quite literally no one wants to deal with. “Fragrance is the first thing I think of for allergies,” says Dr. Lain. “So many skin-care products that we use have certain fragrance in them, and fragrance can come from added perfumes or from essential oils, since all essential oils have fragrance in them.” He notes that essential oils can be major irritants, especially if they’re applied directly to the skin without any sort of dilution. So, your best bet is to look for something unscented, and spot testing anything with a fragrance before going all in. 

Gluten: If you’re steering away from gluten on your plate for legitimate medical reasons (as in: you’re Celiac or severely allergic to wheat, barley, rye, or oats), you should probably stay away from it in your products, too. “There is some data showing that people who are Celiac can be stimulated by topical gluten,” says holistic dermatologist Alan Dattner, MD. Gluten can be lurking in makeup and skin care by way of ingredients like wheat germ and wheat proteins, so if you’re seeing any sort of reaction on your complexion, it may be best to switch to pure oils like coconut and almond wherever you can in your routine. But as Dr. Lain points out, the main concern with gluten products come from ingesting them (gluten particles tend to be too big to seep into your skin unless you have a cut or lesion), so keep them far away from your mouth if using them at all.

And one more thing worth being aware of? Just because a product is “natural” or “clean” doesn’t mean it’s immune from being allergy-inducing. “People think that natural and clean somehow means chemical free, but every product has chemicals, whether it’s an essential oil or some other type of skin-care product,” says Dr. Lain. “Everything is made out of chemicals.” So instead of relying on the fact that your products are clean, natural, or organic as a promise that they won’t irritate your skin, be sure to check the labels, and spot test. After all, it’s better ‘skin safe’ than skin sorry.”

FYI: Hilary Duff replaced her entire routine with coconut oil, and because labels can be seriously confusing, here’s our guide to decoding what, exactly, all of those beauty buzzwords actually mean.