A basic belief behind homeopathy is “like cures like.” In other words, something that brings on symptoms in a healthy person can — in a very small dose — treat an illness with similar symptoms. This is meant to trigger the body’s natural defenses.
For example, red onion makes your eyes water. That’s why it’s used in homeopathic remedies for allergies. Treatments for other ailments are made from poison ivy, white arsenic, crushed whole bees, and an herb called arnica.
Homeopathic doctors (who also are called “homeopaths”) weaken these ingredients by adding water or alcohol. Then they shake the mixture as part of a process called “potentization.” They believe this step transfers the healing essence. Homeopaths also believe that the lower the dose, the more powerful the medicine. In fact, many of these remedies no longer contain any molecules of the original substance. They come in a variety of forms, like sugar pellets, liquid drops, creams, gels, and tablets.