If there’s a “cool kid” in the social-media wellness world, it’s essential oils. In recent years, these plant-derived extracts have been celebrated on Pinterest boards and Instagram feeds for their ability to do just about everything, be it elevating mood, lowering anxiety, easing heartburn, or cleaning grimy floors.

Indeed, essential oils can play a powerful role in promoting wellness. And research suggests that they have some hard-hitting pharmacological functions. But the online fervor raised by enthusiastic advertising campaigns and multilevel marketing strategies has made it more challenging to decipher when essential oils make a great choice for enhanced health and wellness — and when another treatment might make more sense.

Using oils safely and effectively requires basic knowledge about what they are, how they work, and how they can be safely incorporated into daily life. That’s because essential oils can be powerful medicine — and irresponsible use means risking overexposure, toxicity, and allergic reactions. Here’s what you need to know to enjoy the benefits of aromatherapy while sidestepping potential dangers.

How Do Essential Oils Work?

As active botanical compounds that give certain plants their signature aroma, essential oils are substances “that we respond to biologically, emotionally, mentally, and spiritually,” writes certified aromatherapist and licensed massage therapist Cher Kaufmann in Nature’s Essential Oils: Aromatic Alchemy for Well-Being. “Essential oils have the power to change our relationship with our environment and ourselves,” Kaufmann explains.

How exactly do essential oils support psychological well-being? It’s likely via your olfactory senses. “We know that smell is connected to the limbic system, which is an area in the brain that deals with emotions and memories,” says Sarah Villafranco, MD, an emergency-medicine doctor originally from Washington, D.C., who left medicine to create the essential-oil-based skincare line Osmia Organics in Carbondale, Colo.

This is the neurological theory behind aromatherapy: Because your sense of smell is so uniquely connected to emotion and memory, aromas have the power to transport you back to a particular moment — and feeling — in time. It’s why the scent of homemade chocolate-chip cookies can make you feel like you’re 8 years old again, licking the wooden spoon in your grandmother’s kitchen.

Or, as Kaufmann sums it up in her book: “Smelling things you like will reduce stress.”

Then there is the pharmacological potential of essential oils. Tea-tree oil, for example, can be used topically to combat the fungus behind athlete’s foot. Other oils have been shown to have anti-inflammatory properties, and a meta-analysis of 16 studies found that peppermint oil — rather than commonly prescribed pharmaceutical drugs — might be “the drug of first choice” in patients with irritable bowel syndrome (IBS). Peppermint oil is believed to work by reducing muscle contractions in the GI tract, which is similar to how IBS pharmaceuticals work to reduce symptoms. A 2010 data review found that lavender-oil capsules taken orally can be as effective as lorazepam (Ativan) in reducing symptoms of anxiety. Essential oils are also being used as low-risk pesticides in some agricultural practices.

But what really excites experts is essential oils’ potential role in combating the antibiotic-resistance epidemic. Experimental research suggests that essential oils may have the power not just to kill otherwise resistant bugs, but to actually reverse resistance to conventional antibiotics. Most of the researchers haven’t delved into the question of howessential oils might reverse resistance, but they have some theories. One is that when essential oils are used in combination with conventional antibiotics, the duo has a synergistic effect that enhances antimicrobial activity. Some suspect that essential oils, either alone or together with conventional antibiotics, may work by a different mechanism all together. Whatever the case, the early research is considered promising and experts are calling for more work to be done in the field.

Essential-Oil Safety

An essential oil’s power to kill germs is a result of its intrinsic toxic potential. “Toxicity in essential oils is an attribute we welcome when we want them to kill viruses, bacteria, fungi, or lice,” writes Robert Tisserand, an aromatherapy educator, and Rodney Young, PhD, a lecturer in plant chemistry and pharmacology at the University of East London in the United Kingdom. “And human cells share some characteristics with these very small organisms.” In other words, essential oils have the power to destroy other organisms, whether they are dangerous pathogens or delicate human skin. The oils don’t discriminate.

So when it comes to essential-oil use, knowledge is key. “Essential oils are complex chemical components that we can use to our benefit, provided we are using proper caution and we know a little bit about what we are doing,” says Kaufmann.

In general, essential-oil use is considered very safe. There hasn’t been a single reported case of poisoning from ingesting one (when administered by a practitioner). But with all the social-media buzz around essential oils, more people are adopting a DIY approach — and practitioners see their share of overexposure, toxicity, and allergic reactions.

“We’re seeing more reports of injuries because more people are using essential oils. Poison centers are reporting an increase in ingestion,” says Carol Scheidel, RN, BSN, CCAP, and CEO of R.J. Buckle Associates, a leading provider of courses in clinical aromatherapy to licensed health professionals in the United States.

Scheidel opposes any internal ingestion without the guidance of a trained aromatic-medicine aromatherapist. That’s because oil and water don’t mix, so adding essential oils to water-based liquid doesn’t dilute them. It simply allows them to come into contact with sensitive internal tissue at their full, undiluted strength. “Adding essential oils to drinking water can be dangerous. Your esophagus is made of very delicate tissue, and essential oils can damage it.”

Essential oils also trigger different responses in different people. A scent that relaxes one person might trigger a migraine in another, which is one reason that following suggestions you read online can backfire. “I don’t recommend using social media to get your recipe,” says Kaufmann. “One scent in that blend might not be a match for you, and it can create more harm than good.”

A similar problem can happen in children, says Amy Kreydin, board-certified reflexologist and certified clinical aromatherapy practitioner in Austin, Texas. Kreydin points out that young children are thought to have overlapping sensory reactions to smells. An adult who is exposed to lavender might feel a sense of calm — and that’s it — but a child might experience a cacophony of overwhelming sensations in response to the same scent, including sounds and swirling colors.

“Someone might think, ‘This lavender will really help calm down my 10-year-old at night,’ but what they’ve really just done is bring the marching band into the room.”

Most overexposure injuries also happen with children, for whom a lower dose can trigger an adverse reaction. Overexposure taxes the liver, which processes all the volatile oils we come in contact with. “The liver doesn’t mature until the teen years,” Kreydin explains. “So you cannot give an adult dose to a child and expect that they can metabolize it in the way an adult could.”

But overexposure can be a problem for adults, too. The olfactory systems get fatigued after about 30 minutes, so we stop smelling even the most obvious aromas around us — risking overexposure and eventually sensitization — the term aromatherapists use to describe essential-oil intolerance.

“In the case of sensitization, the kidneys and liver cannot metabolize that oil anymore,” says Kaufmann. “Before I learned about essential oils . . . I wore this one oil all the time. Now I have this spot on my wrist that will break out even if I just smell it!”

How to Use Essential Oils

To safely incorporate essential oils into your daily life, consider these top tips from the experts:

1. Dilute, dilute, dilute. Never put undiluted essential oils on your skin. This can set you up for sensitization and allergic reactions. Essential oils should always be diluted with a carrier oil — not with water or a different non-oil-based liquid, because the two won’t mix. When mixing with a carrier oil, opt for jojoba or fractionated coconut oil because of their long shelf life. Avoid sweet-almond oil for long-term use, advises Scheidel, because it goes rancid quickly.
2. Don’t confuse “more” with “better.” Marketers and lay practitioners often make the case that essential oils are safe because they come from nature. But these compounds are highly concentrated extracts that are far more active (and potentially dangerous) than in their as-it-exists-in-nature counterparts. When using essential oils, says Scheidel, dosage is critical.
3. It pays to invest. Quality matters, and in the case of essential oils, price almost always reflects quality. “It takes 10,000 pounds of actual rose-petal blossoms to make one pound of rose essential oil,” says Villafranco. That’s expensive from a labor and raw-materials standpoint, and it’s a big incentive for unethical producers who hope to lure in customers with lower price points. “Some producers assume the average consumer won’t know if an oil has been diluted with olive oil or cut with something else,” she continues.
4. Test your oil’s purity. Paying more helps safeguard against purchasing an oil that’s been cut with cheaper ingredients, but you can also test the quality of an essential oil by placing a drop on a piece of white computer paper, says Villafranco. “If there is a grease stain on the paper after 24 hours, the oil has been cut with a carrier oil. If it is pure, it will evaporate. You might see the faintest ring, but nothing more.”
5. Don’t buy “absolutes.” If you see “absolute” on a label, it means that it is a petroleum-based byproduct of the essential-oil extraction process. You don’t want this on your skin, says Scheidel.
6. Choose organic — and look for third-party certification. Organic oils won’t expose you to the pesticides and herbicides used in the conventional growing process. If you still have concerns about the quality of an oil, look for independent lab assessments of the oils as noted on the label. Third parties certify that a specific oil contains the chemical constituents it says it does.
7. Ignore “grade” scales. If you see the terms “clinical grade” or “medical grade” on labels, it’s easy to think you are getting the highest-quality product. But these are just marketing terms — they’re unregulated, and they don’t have any meaning when it comes to quality assessment.
8. Pick the right tools. Look for diffusers that are made specifically for essential oils. They are designed to break up the particles in a way that makes the vaporized oils easier for the body to process, says Scheidel. Never diffuse oils in products made of plastic or Styrofoam, which can release plastic particles into the air.
9. Diffuse smartly. If you want to add essential oils to a humidifier, don’t put drops directly in the water — the oils will break down the internal plastic parts of the humidifier and begin to send vaporized plastic into the air. Instead, put a drop or two on an organic cotton ball and put that cotton ball into the vapor outlet, says Scheidel. And don’t diffuse continuously for more than 30 minutes, adds Kreydin, because you risk overexposure.
10. Don’t diffuse at work or in schools. Everyone responds to essential oils differently — and children are especially susceptible to the effects. Also, some essential oils are contraindicated with certain medications, causing adverse reactions or preventing the medicine from doing its intended job.
11. Give pets a chance to get some fresh air. Essential oils can be hard for pets to process. If using a diffuser, always make sure pets can leave the room if they need some fresh air. Pay special attention to cats, who have a particularly hard time processing essential oils. All oils can be hard for cats to process (thanks to a missing liver enzyme that helps metabolize certain types of compounds), but they are specifically sensitive to sweet-birch oil, peppermint oil, cinnamon oil, clove oil, pennyroyal oil, eucalyptus oil, tea-tree oil, and pine and citrus oils.
12. Don’t use oils that have gone bad. How can you tell? Smell it. “Does it smell like what you anticipated?” says Scheidel. If not, toss it. The oils that go bad the quickest are bergamot, lemon, lime, and sweet orange. Resinous oils — like frankincense, Douglas fir, cedarwood, pine, and the balsams — tend to last longer.
13. Pay attention to lavender varieties. Lavender is almost always marketed for its relaxing powers — but there are many different varieties of lavender, and not all of them are ideal for bedtime. Certain types, such as spike lavender, are actually stimulating.
14. Don’t use single oils. As much as possible, create oil blends for personal use rather than using single oils. This helps inoculate against entrainment, when the brain associates a particular smell with a particular time in life. If you diffuse rosemary all the time during a period of illness or grieving, you may not be able to smell it again in the future without being reminded of those times.
15. Rotate your oils. Give your body a break from specific scents or blends by rotating the oils you use every two to four weeks, says Kaufmann. This helps prevent overexposure and sensitization.
16. Don’t use essential oils for everything. When another intervention is appropriate, try that first. “If you have a dehydration headache, no essential oils will help you,” Kreydin explains. “You need to drink some water.”
17. Choose well-researched oils and blends. “If you are going to work with essential oils on your body (diluted in a carrier oil), choose an oil that has been studied extensively, whether for its analgesic, antibacterial, or calming properties,” says Villafranco.
18. Don’t ingest essential oils without the guidance of a certified practitioner. Ingested oils can do significant harm, so always consult a practitioner who is certified in medical aromatherapy before taking an oil internally. Even adding a drop or two of an essential oil to a glass of water can be dangerous. Oil and water don’t mix, so your esophagus and stomach lining will be exposed to the undiluted oils in the water.
19. Be careful in the sun. Some essential oils, particularly the citruses, dramatically increase the risk of sunburn, or phytophotodermatitis. So don’t wear these oils when you’re out in the sun, and be cautious on your next tropical vacation — even drinking a margarita rimmed with lime juice can lead to sunburned lips.
20. Remember that responses are different for different people. A scent that relaxes you and puts you straight to sleep might make another person agitated or restless. This is another reason to treat recipes you find online with caution, and to think small when using essential oils. When in a classroom, meeting room, or other group space like a group fitness class or gym, use a personal inhaler that only you can smell. And resist the urge to turn on your diffuser for your next dinner party; you may unknowingly give half your guests a headache.
21. Don’t believe everything you read online.“Keep in mind that many Facebook pages and other social media are run by product representatives, which makes them a biased place for safety information and learning,” Kaufmann advises.

By Laine Bergeson Becco, reposted with permission from Experience Life.