There is definitely credible science behind certain benefits for certain essential oils,” says Cynthia Bailey, MD, a dermatologist in Sebastopol, CA. “But you have to choose wisely, and you cannot use them indiscriminately.”

How Essential Oils Work

As far back as 1,000 A.D., healers used mechanical presses or steam to extract essential oils from aromatic plants. Today, practitioners can rub oil-infused lotions on the skin, where the compounds are absorbed into the bloodstream. Or they can diffuse them into the air where, once inhaled, they bind to smell receptors and stimulate the central nervous system, says Joie Power, PhD, a neuropsychologist and aromatherapist who has taught nurses how to use the oils for decades.
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Complementary and Alternative Therapies

More than 30% of U.S. adults use health care that’s outside of mainstream Western medicine. These are often called alternative or complementary. Though they may seem similar, they’re two different approaches: Practices used together with conventional medicine are complementary, and ones used instead of conventional medicine are alternative.

Research behind them remains fairly scarce, with scientists only recently using controlled human trials. But thanks to a growing number of studies showing  how they work, the oils are being used more in hospitals and clinics for stress relief, pain and nausea relief, and even to prevent bedsores.
One recent study of 300 patients found that those who breathed a mixture of ginger, spearmint, peppermint, and cardamom suffered much less nausea after surgery. Others have shown that lavender oil can lower levels of the stress hormone cortisol, and inhaling lemongrass aroma before a stressful event can prevent anxiety. Studies also show that tea tree and oregano oils can fight microbes, making them popular treatments for dandruff and toe fungus. Others can be used as an anti-inflammatory.
There is so much misinformation out there right now, it really concerns me.
Joie Power, PhDThe trouble, say critics (including long-time aromatherapists), is that companies overstate their potential.
In 2014, the FDA sent warning letters to two direct-selling companies -- doTERRA and Young Living -- for making unsubstantiated claims that their oils could treat everything from herpes to Ebola.