In a seminar held in the dimly lit back room of a New York yoga studio, Holly Slayton, a “wellness advocate” for DoTERRA, a popular brand of essential oils, told me her product could cure my ADHD, acne, sleep issues, menstrual cramps, sore muscles, nausea and more.

As Slayton passed sandalwood and lavender oils around to a small group of women to smell, she commented on the various ways you could use the oils to treat health conditions. You can diffuse them, rub them on your skin or eat them, she said, or put a few drops in a capsule to swallow. Stomach problems? Put a special oil for digestive health on the outside of your stomach. “After 15 minutes, you can taste it in your mouth,” she said.

At the end of the class, she offered up vegan cookies she had baked using essential oils, and as I left, she handed me a pamphlet explaining how oils could be used to treat anything from depression and bacterial infections to influenza and bleeding.

Reached by phone, a DoTERRA representative said the company “would not allow” this type of promise at an event and would “take down” this sort of language if posted online. But Slayton is far from the only voice claiming branded essential oils have performed medical miracles: This class was just the tip of the lavender-scented iceberg. These types of claims are all over the internet.

The essential oils industry is massive — and lucrative

It should come as no surprise that none of these claims are supported by health professionals. Wellness advocates for essential oils often earn their keep by promising miracle cures that aren’t medically or even legally sound. Essential oils are not regulated by the Food and Drug Administration, so it’s unlawful to make medical claims about their use.

These false promises have added up to massive profits for companies like DoTERRA, which boasts 5 million customers and $1 billion in annual sales in 2015, a company representative said. The latest statistics from Transparency Market Research suggest that the essential oils industry will be worth $27.5 billion by 2022.

The two biggest essential-oils companies, DoTERRA and Young Living, run on multilevel marketing, a system in which sellers recruit sellers who recruit sellers, ad infinitum. The wellness advocates, as the salespeople are known, trawl social media to find new sellers and hawk products: There are nearly 4 million photos on Instagram tagged #EssentialOils, 1.5 million tagged #DoTerra and 1.5 million tagged #YoungLiving. Wellness advocates get a commission for selling oils and a commission for recruiting new sellers.

Experts are skeptical

Many sellers I spoke to not only endorse but seem to genuinely believe in the benefits of their essential oils. Sandy Baggot, a DoTERRA salesperson, said she has no dental insurance but used clove oil to treat a toothache. “After just a couple of drops of putting it on there, the pain was gone; whatever inflammation or whatever infection was in there, it went away.”

Clove oil can be used as a topical anesthetic, dentist Dr. Matthew Messina said in an interview. But while clove oil can relieve some pain temporarily, he doesn’t recommend anyone use it for a toothache. “One of the challenges [clove oil] presents to us in dentistry is that it masks other symptoms,” Messina said. “The most common cause of what people call a toothache is when the nerve of the tooth has become infected ... In other words, bacteria come in.” Dentists have a way to remove that bacteria: a root canal.

“After just a couple of drops of putting it on there, the pain was gone.”

“In the short run, [clove oil] might make [a toothache] feel a little better, but in the long run the problem is going to come back and it’s going to come back with a vengeance,” he said. So by masking the pain and avoiding the dentist, Baggot could have been making the problem worse. If you have tooth pain, you should see a dentist as soon as possible, Messina said. “If we wait too long, we risk losing the tooth.”

There’s a bible for essential oils — and it’s filled with dangerous, false claims

What are essential oils useful for? Mostly aromatherapy, which has been shown to be effective for anxiety relief and sleep. They are not, however, meant to be used for medicinal purposes, and the medical claims people are making are dubious.

Many of these claims come from a book called Modern Essentials: The Complete Book of Essential Oils and Aromatherapy. Cited in many seminars like the one I attended, it contains lists of ailments, illnesses and disorders that can be treated with essential oils.

Ross Blocher and Carrie Poppy, hosts of the podcast “Oh No, Ross and Carrie,” research different pseudosciences on their show. For a recent episode, they attended an essential oils seminar where they were told that their friend Drew, who has cerebral palsy, could be cured using essential oils.

The trio looked up cerebral palsy in Modern Essentials and found a suggested oil treatment. Drew followed the instructions and put sandalwood on his affected arm every day for a few weeks. Nothing happened. “Bizarrely, Drew still has cerebral palsy!” Poppy told me, jokingly.

“Bizarrely, Drew still has cerebral palsy!”

Their seminar, apparently, was a lot like mine: full of specious claims about the benefits of oils. “Boy, did we hear some stories,” Poppy said. “We heard about people who had cured their child’s illness by putting oil on his feet. … Like, he had pneumonia and they put something on his feet and it was magically cured. We thought, ‘Huh, that sounds more like the placebo effect.’”

Dr. Stephen Barrett, a retired psychiatrist and consumer advocate, said essential oils are useful for their scents and nothing else. “The idea that it’s a medical system is preposterous,” he said in an interview. “There are a number of books written saying that this oil can help this condition and that oil can help that condition. I think that’s all a wad of bologna.”

Why it’s so hard to stamp out a wellness hoax

The FDA issued DoTERRA a warning about making false health claims in 2014. Its letter detailed the erroneous medical claims on DoTERRA’s website, including assertions that oils can treat anxiety, infections, asthma, high cholesterol and more. It also pointed out false claims made by DoTERRA Wellness Advocates on their social media pages. But this clearly hasn’t changed the way some wellness advocates are behaving.

A company representative told me DoTERRA tries to keep a handle on false claims: A team of about 53 employees is tasked with scanning social media posts and attending events hosted by wellness advocates to ensure compliance. They generally ask advocates to remove content with claims that aren’t FDA-compliant — a technique that works 99% of the time, the representative said. If someone refuses to stop posting false claims, they’re booted from the organization.

Barrett said the real problem is the FDA’s and Federal Trade Commission’s unwillingness to take multilevel marketing regulation seriously. He said the FDA has “historically had little interest” in investigating these regulations.

“I think that’s awful, but that’s been the FDA policy,” Barrett said. “The Federal Trade Commission has more cases than they can handle, and if they were to go after all the multilevel companies that they know about, they wouldn’t have any time to do anything else.”