Navigating the world of skincare is tough. And it gets even more perplexing when the products that claim to be nice to your skin are filled with ingredients that are not, in fact, as gentle as they appear, but are actually incredibly irritating—like essential oils.
Though they sound sweet and innocent, essential oils are highly concentrated essences that can cause skin damage and irritation. “With the rise of the natural skincare movement, more and more products are being formulated with essential oils, which are known irritants,” says dermatologist Joshua Zeichner, M.D., director of cosmetic and clinical research at Mount Sinai Hospital in New York City. “There’s this idea that natural automatically means gentle, but poison ivy is natural, and you’re not putting that on your skin.”
Because every product is formulated differently, your “organic” lavender moisturizer may only contain a hint of lavender oil, while your random drugstore moisturizer may contain an entire lavender field. But before you freak out and toss out everything in your medicine cabinet, know that despite their cons, some essential oils (in diluted doses) do have pros, too. To help you make sense of it all—and avoid any future rashes—I’ve broken down the four most popular oils, ahead.
#1. Tea Tree Oil
Yes, the very same oil seen in your acne-curing products is also a major irritant—at least, when used incorrectly. “Tea tree oil, or TTO, has both antimicrobial and anti-inflammatory benefits, meaning it can calm inflammation in the skin and also reduce acne-causing bacteria,” says Dr. Zeichner. In diluted form (like a drop mixed with a water and lightly dabbed over your skin), it’s fairly innocuous and can even be an excellent acne-fighter for sensitive skin—but rarely will you find it that diluted.
“You really never know how much TTO is in a product until it’s too late, when your skin is already itchy, dry, and irritated,” he says. “Plus, people tend to over-apply natural products—especially natural acne products—which basically guarantees irritation.” That’s not to say you need to swear off TTO forever; instead, make sure that’s it’s not one of the first few ingredients (and, thus, the highest concentration) listed in a formula. And before you use any TTO product, first patch test it under your ear by your jaw to see if you have any adverse reactions.
#2. Mint Oils
If you’ve ever felt the mild burn of a too-minty toothpaste in your mouth, you probably won’t be surprised to know that mint oils, like peppermint, wintergreen, pennyroyal, and balm mint, are almost always a bad idea for your skin. “Mint oils are very fragrant and potent, and can be a huge trigger for allergic contact dermatitis,” says Dr. Zeichner.
Allergic reactions often don’t occur until the second or third time you encounter something irritating, so you could use a mint-filled face mask or peppermint shampoo once or twice with zero problems, and then develop itching, redness, and burning the third time. If you’re concerned, it’s best just to avoid mint oil altogether.
Luckily, products high in mint are usually easy to spot: They’ll often use words like “cooling,” “fresh,” “invigorating,” and “tingly,” which are basically code for “dermatologists hate this.” Still, double-check the ingredients list just to make sure you know what you’re slathering on.
#3. Citrus Oils
Ah, citrus oils—the bane of every derm’s existence. “We see a lot of citrus oils, like lemon and orange, in DIY skincare recipes, because they’re thought to brighten the skin and fade dark marks,” says Dr. Zeichner, “but in reality, they’re so acidic that they often just cause intense irritation, instead.” If your skin is especially prone to hyperpigmentation, that irritation can actually worsen or create even more darkness and scarring—i.e. the opposite of your goal.
Citrus oils (including orange, lime, lemon, grapefruit, and bergamot) have an extra special layer of risk to them: They can cause photoallergic reactions, meaning they react with the sun to cause phototoxic burns. “It’s not common, but I’ve had patients come in with blisters from cutting limes before prolonged sun exposure,” says Dr. Zeichner.
Of course, your face cream with a bit of lemon or grapefruit oil at the bottom of the ingredients list isn’t necessarily going to lead to a blistering breakout. But a cluster of citrus fruit oils (as you’ll often see in products) can still be irritating, especially to sensitive skin types. If you’re looking to brighten dark marks, opt for a tried-and-true spot-fading treatment, instead.
#4. Lavender Oil
Lavender oil is the popular kid of essential oils: It’s in every diffuser, detergent, mist, and bubble bath, and its revered for its stress-soothing, itch-fighting, anti-inflammatory properties. And yet, despite all of its street cred, lavender oil is a known skin allergen, even in a super-diluted form.
“Like mint oil, lavender oil is really fragrant and strong, which is great for aromatherapy, but less so for skincare,” says Dr. Zeichner. Still, a tiny bit of diluted lavender oil may not cause irritation if you’re someone who has never dealt with sensitivities. But if you have temperamental skin (like moi), then using lavender-filled products is like playing a game of risk. “Any amount of contact with an allergen, like lavender oil, can be too much for a susceptible person,” says Dr. Zeichner (“susceptible person” including those who frequently battle rashes, hives, and allergic reactions).
“Realistically, everyone’s reactions to essential oils will be different, so there’s no point in ruling them out altogether, especially if you enjoy the scents,” he says. “It just means you have to be smart about patch-testing and recognizing adverse side effects, like itching, burning, or redness, so you can stop use immediately.” And if you do experience a reaction, immediately wash off the oil, slap on some 1 percent hydrocortisone cream, and get yourself to a doctor’s office.