Homeopathy has grown increasingly popular in the United States, with homeopathic remedies being sold at large retailers like Walmart and Whole Foods. But the practice isn't based in accepted clinical evidence—though that doesn't mean mainstream medicine can't learn something from it, Stephie Grob Plante writes for Vox's "The Highlight."

Cheat sheets: Evidence-based medicine 101

What is homeopathy?

Homeopathy is a practice of alternative medicine that has two main, guiding principles: first, that "like cures like," or that a substance that causes a disease's symptoms in a healthy person can cure that disease in someone who has it, and second, that the lower the dosage, the more potent the remedy.

According to Plante, homeopathy was invented by Samuel Hahnemann, a German physician in the 18th century who had become disillusioned with modern medical practice.

By the 1900s, homeopathy had become recognized by the U.S. government. Royal Copeland—a surgeon, senator, and New York City health commissioner—helped this along by using his medical credentials to make homeopathy seem credible, according to Plante. Copeland also helped get homeopathy recognized in law through the Food, Drug, and Cosmetics Act of 1938, and FDA still oversees homeopathy today.

Now, homeopathy is a $1.2 billion industry used by an estimated five million adults and one million children, Plante writes, and leading homeopathic brands like Boiron and Hyland are sold in major retailers nationwide.

According to Michelle Dossett, an assistant professor of medicine at Harvard Medical School who profiled homeopathy users in the American Journal of Public Health in 2015, people who use homeopathy tend to be female, young to middle age, non-smokers, have low body mass indexes and have a tendency to make healthy lifestyle decisions.

However, according to Plante, there also are homeopathy users who simply have grown disillusioned with modern medicine, as well as those who use homeopathy as a complement to modern medicine.

While many homeopathy users self-prescribe the remedies, there are homeopathic practitioners who undergo homeopathic-specific training that can help patients determine the homeopathic treatments they should use. Today, many of those practitioners also are trained in conventional medicine as doctors or nurse practitioners, Plante notes.

A lack of evidence, and a potentially dangerous practice

But homeopathy isn't based in accepted clinical evidence, Plante writes, and some users have discovered that fact to their chagrin.

Natalie Grams, a nurse practitioner who underwent more than 300 hours of homeopathic training and used to be a homeopathic practitioner, said she began conducting in-depth research on homeopathy to write a book defending the practice. But while conducting that research, she found multiple clinical trials that showed no hard evidence that homeopathic remedies worked.

Homeopathy also often is misidentified as "natural" medicine, Plante writes. According to Edzard Ernst, a physician and homeopathy researcher who is a noted skeptic of the practice, there's "nothing natural" about homeopathy. In his 2016 book "Homeopathy: The Undiluted Facts," Ernst wrote that some remedies include alcohol that's been exposed to x-rays in order to minimize the effects of radiation therapy, and even ground up fragments of the Berlin Wall to "cure a patient's communication problems."

And Plante notes that homeopathic remedies often don't contain any molecules of their supposed "active" ingredients, often because they're so heavily diluted.

Critics of homeopathy argue that any perceived benefit of homeopathic remedies is a result of either the placebo effect, or what's called the nocebo effect, in which a diagnosis, pill, or treatment causes negative symptoms associated with that diagnosis, pill, or treatment in a patient.

"It's like smoke," Grams said, "like something that if you want to grab it, if you want to get ahold of it, it just vanishes. It's just a big illusion."

And Grams isn't the only one who was disappointed once she began learning facts about homeopathy. Research has found that, once consumers learn more about homeopathic remedies, they view the remedies negatively. For example, one survey conducted by the Center for Inquiry found that 41% of respondents felt negatively about homeopathic remedies "[o]nce [they] were told the essential facts about homeopathy's pseudoscientific claims."

Grams said she worries that people who use homeopathic remedies will do so as an alternative to medicine, forgoing proven treatments for remedies she dismissed as nothing more than sugar pills. "You might think, 'Oh, if that remedy doesn't help me, I'll use another, I'll use another,'" she said. "And you lose time. If you have cancer, time is life."

To their credit, most homeopathic practitioners recommend patients see general practitioners and primary care physicians concurrently with their homeopathic therapy, Plante writes. Doug Brown, a former family nurse practitioner who is now a homeopathic practitioner, said, "Nothing can be a substitute for what modern medicine can offer in critical, life-threatening situations," but he added, "That's not to say that homeopathy doesn't have a role."

What mainstream medicine could learn from homeopathy

But just because homeopathy isn't based in accepted clinical evidence, that doesn't mean there's nothing mainstream medicine can learn from the practice, Plante writes.

"I think there's a big disconnect between what conventional medicine aspires to do and what actually happens sometimes in the consultation room," Dossett said. "Because physicians face incredible pressures these days."

A 2017 study found that U.S. doctors spend just 20 minutes with their patients, and another 2017 survey found that just 11% of patients and 14% of primary care physicians feel "that they have all the time they need together."

That's where homeopathy can come in, Plante writes. One German study of homeopathy patients published in 2013 found empathy was the key to establishing a positive physician-patient relationship and achieving positive outcomes.

"Homeopaths listen to their patients. They believe their patients. Individualization is the most basic driver of their medical philosophy," Plante writes.

The American Institute of Homeopathy in its description of the practice states, "Homeopathy is holistic because it treats the person as a whole, rather than focusing on a diseased part of a labeled sickness." Mainstream medicine could stand to learn this lesson from homeopathy, Plante writes, "and trust more in what their patients feel to be true." She contends, "Doing so could be the key to bridging the gap between conventional and alternative, for medicine that is truly holistic and integrated" (Plante, "The Highlight," Vox, 10/23).