Homeopathy believes that "like cures like" and uses highly diluted substances that produce symptoms in healthy people to treat illnesses with similar symptoms, triggering the body's natural defenses. It treats various conditions like allergies, migraines, and irritable bowel syndrome. While some use homeopathy for chronic illnesses, doctors are divided on its effectiveness since its theories don't align with chemistry and physics principles, and remedies contain no active ingredients. People can buy over-the-counter homeopathic remedies but should discuss their use with a doctor to check for safety and interactions with other medications.