What it is: The North American Society of Homeopaths defines homeopathy as “an advanced, effective, and gentle system of holistic medicine that has been successfully used for over two hundred years and on every continent.”

About five million adults and one million children have used homeopathy in the United States, according to a 2012 National Health Interview Survey on Americans' use of complementary health approaches.

Homeopathic remedies are typically made from plants or minerals that are highly diluted using water or alcohol. They are typically delivered in small pills or tablets, but can also be delivered by ointment, tincture, or suppositories.

The system has three basic guiding principles: the law of similars, minimum dose, and single remedy.

Samuel Hahnemann, the German physician and creator of homeopathy, took the law of similars from Hippocrates’ idea that “like cures like.” He suggests using substances that would cause specific symptoms in a healthy person to treat those same symptoms in those who are ill, but with doses as small as possible. 

The concept of single remedy refers to the idea that, generally, practitioners prescribe only one medicine at a time to help stimulate the patient's internal healing on a mental, emotional, and physical level. Combining treatments is thought to reduce efficacy.

What it’s used for: Homeopathy is used to treat many conditions, especially those related to pain, such as teething or muscle soreness, or for common illness like colds and flu. You may already have used homeopathic products without knowing it. Arnica is a popular homeopathic medicine that comes from a daisy-like plant and is used to help combat sore muscles or bruises. It is in products like Arnicare® and Arniflora®, which can be found next to the Bengay® in the pain relief aisle of many pharmacies. 

You may also be familiar with a product like Coldcalm®, which is a tablet that dissolves under your tongue to help relieve cold symptoms such as sneezing, runny nose, and sore throat and can often be found next to the Zicam® in pharmacies. (Zicam is marketed as a homeopathic remedy but technically isn't one because it doesn't follow the three principles above.)

Working with a practitioner: A visit to a homeopath might look quite different from a visit to other health professionals. You can expect an initial visit to last up to three hours, while the practitioner gets to know you and any symptoms you are experiencing.

Julia Eastman, a classical homeopathic physician, says you can expect to talk about your “personal health history, family medical history, food likes/dislikes, how you feel about your job, family relationships, what major grief and joys you've experienced, the kind of weather you like/dislike, etc., and a host of other questions that enable the homeopath to get a sense of each patient as an individual.” After the first visit, a homeopath will pick a single remedy to work with.

Unlike conventional medicine, treatment is determined by an individual's needs, not necessarily by the particular problem. For example, two patients who suffer from arthritis may receive different treatments based on factors revealed in their assessment.

Where to find it: Homeopathic practitioners can be found throughout the world. Some European countries, like France, Germany, the Netherlands, Italy, Switzerland, and Portugal have integrated homeopathy into their healthcare systems. Homeopathic hospitals can be found throughout India. In the United States you can find practitioners through organizations like the National Center for Homeopathy.

Does it work: The National Center for Complementary and Integrative Health suggests there is little rigorous scientific evidence to support the practice. The Homeopathic Research Institute argues that homeopathic research is in its infancy and that results are promising. Physician Edzard Ernst explains that while science doesn't back up homeopathy, he has seen it work repeatedly for patients, and that perhaps it acts as a placebo, which brings up further ethical questions for a physician. There are also questions within the homeopathy community about whether homeopathy can be assessed with the same tools as conventional medicine when its methods are so different, and perhaps in that difference is where the answer to homeopathy's effectiveness and popularity can be found.

To learn more about homeopathy, watch this talk from Katina I. Makris, homeopathic healer and author of Out of the Woods: Healing Lyme Disease, Body, Mind, and Spirit.