Are these trendy machines actually healthy? Experts share exactly what you need to know before purchasing and using an essential oil diffuser.

By By Gabrielle Kassel
January 25, 2019
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Photo: Denise Erickson/Getty Images

Essential oil diffusers are the cool, millennial version of a lava lamp. Turn on one of these sleek-looking machines and it transforms your room into a soothing haven that's serious #selfcaregoals.

ICYDK, diffusers work by dispersing essential oils into the surrounding air (usually via steam, air, or heat) which creates a chill ambiance, makes the entire room smell ahh-mazing, and may have some serious health perks. (See: What Are Essential Oils and Are They Legit?)

But are there any downsides and dangers to this wellness world obsession? Turns out, the answer is yes. Here's what you need to know before you turn that diffuser on.

Pick the Right Kind of Essential Oil Diffuser

A quick scroll through Amazon's essential oils and diffusers can make you feel like you need a degree in aromatherapy to participate. That's why we asked clinical biobehavioral-health researcher, certified aromatherapist, and natural beauty expert Leigh Winters to narrow down which kind of diffuser to invest in. According to Winters, these are the three most popular types:

Ultrasonic diffusers use electronic frequencies to create vibrations in water, which creates a fine mist of water and essential oils that's released into the air. Because they use water, they're an especially popular option in the winter for humidifying the air too-there are even diffuser-humidifier combos which you can get for as little as $25. "The downside is that most are made from plastic, which is not as eco-friendly and some experts believe that plastic might negatively interact with and affect the quality of your essential oils," says Winter. Try it: Saje Aroma Om Deluxe Ultrasonic Essential Oil Diffuser ($130)

A nebulizing diffuser works by first breaking the essential oils into tiny molecules before dispersing them into the room using only air, explains Winter. "Usually, these come with a timer." Try it: Opulence Nebulizing Essential Oil Diffuser ($109)

Heat (sometimes called "candle") diffusers are sexy-looking devices that use heat (usually from a candle flame) to diffuse the oil. (Related: How Trying Essential Oils Helped Me Finally Chill the Eff Out) They're thought to be less effective because the heat can change the chemical properties of the oil, therefore altering its effectiveness as well as the smell. Try it: SouvNear Ceramic Oil Diffuser ($10)

Winter's recommendation: Invest in a quality glass nebulizer or BPA-free plastic ultrasonic diffuser. (For options, check out these diffusers that double as tasteful decor.)

How to Use Your Diffuser Correctly

Breathing in non-air things is generally considered bad (think: air pollution, e-cigs, etc.)-but it's generally okay to breathe in essential oil particles from a diffuser, as long as they are high-quality oils and you follow the guidelines below, read bottle labels, and follow your diffuser instructions, says Goldstein.

1. Invest in quality essential oils. This guide can help you find *quality* essential oils, but there are a few other things to keep in mind. You don't need to use the same brand oils as your diffuser, say Winters. Your best bet is to only buy essential oils that are 100 percent pure (unadulterated by potentially toxic additives), and from a company that you trust. Make sure that the plant's botanical name is on the bottle (ex: lavender is lavandula angustifolia) and its country of origin should be listed too, as Ariana Lutzi, N.D., a nutrition consultant for BUBS Naturals previously recommended.

2. Check for allergies. Test the oil ahead of time to make sure you're not allergic, suggests naturopathic doctor Serena Goldstein, N.D. "Put one drop of the oil and half a teaspoon of coconut oil on the cotton part of a Band-Aid, and then apply to your inner arm, just below the wrist." If there's no reaction after about 15 minutes, Winters says you should be good to go.

3. Heads up if you have asthma. Be extra cautious while using essential oils if you have asthma. "Asthma patients can have negative reactions to compounds in the air," says Stephanie Long, M.D. In fact, some studies have found that essential oils release organic compounds that can be irritating to airways, causing respiratory symptoms in people with the condition.

4. Check with your doc if you're pregnant. If you're pregnant Long recommends talking with your health care provider before using essential oils at all. "There is very little data about essential oil use during pregnancy. While most essential oils are okay to use for most patients, your provider will be able to take your personal pregnancy health history into account when determining if a specific product is safe for you."

5. Extra oil doesn't equal extra benefits. Every diffuser will have a different recommendation for the number of drops you use, says Winter-use that amount or less. If you use too much, you may experience headaches or nausea. That drop count stands even if you're planning to combine oils. "Combining or blending oils can enhance the therapeutic benefit you're looking to achieve," says Winter. There's not really a right or wrong way to blend them, but she suggests blending oils of the same brand and with the same known therapeutic benefits (for example, both are known to relieve pain or reduce stress).

6. Clean your diffuser. Ideally, you should wipe down your diffuser after each use to prevent cross-contamination and mold build-up, recommends Omid Mehdizadeh, M.D., otolaryngologist and laryngologist at Providence Saint John's Health Center in Santa Monica, CA. The instructions will also tell you how often you need to deep clean your particular device to keep mold at bay. (The standard recommendation is once a month). And if your diffuser uses water, don't let the water sit in the diffuser for days at a time without use. (Related: The Essential Oil Hack to Wake You Up In the Morning)

7. Don't leave it on all day. While leaving your new device on to create an all-day, all-night aura of relaxation might sound like a good idea, it's not. According to Goldstein, the healthiest practice is to keep it on for about 30 minutes, which is enough time to disperse the oil throughout a room, and then turn it off for at least an hour to avoid negative side effects like headaches. However, depending on your machine, Winters says it may be fine to keep it on for a few hours. "Some diffusers come with a set timer that disperses the aromatic molecules into the air only every few minutes for about a few hours and then automatically shuts off so you don't have to worry too much." Your game plan: Experiment with keeping it on for 30 minutes at a time and make sure you don't experience any side effects.

8. Be mindful of pets. Pet owners-especially cat owners-should pay close attention to how their pet is responding to the new fragrance. The ASPCA cites essential oils as one of the most common toxic causes of tremors in cats, explains Dr. Mehdizadeh. If you notice your pet begin to fall ill, open the windows, ventilate the area, and take them to the vet if symptoms get worse. And make sure to check the ingredient list; sometimes the pet's adverse reaction isn't to the oil itself, but to the added ingredients.