Homeopathy is a complementary or alternative medicine. This means that homeopathy is different from treatments that are part of conventional Western medicine in important ways. It's based on a series of ideas developed in the 1790s by a German doctor called Samuel Hahnemann. A central principle of the "treatment" is that "like cures like" – that a substance that causes certain symptoms can also help to remove those symptoms. A second central principle is based around a process of dilution and shaking called succussion. Practitioners believe that the more a substance is diluted in this way, the greater its power to treat symptoms. Many homeopathic remedies consist of substances that have been diluted many times in water until there's none, or almost none, of the original substance left. Homeopathy is used to "treat" an extremely wide range of conditions, including physical conditions such as asthma and psychological conditions such as depression.There's been extensive investigation of the effectiveness of homeopathy. There's no good-quality evidence that homeopathy is effective as a treatment for any health condition. When you first see a homeopath, they'll usually ask you about any specific health conditions and your general wellbeing, emotional state, lifestyle, and diet. Based on this, the homeopath will decide on the course of treatment, which often takes the form of homeopathic remedies given as a pill, capsule or tincture (solution). Your homeopath may recommend that you attend one or more follow-up appointments so the remedy's effects on your health can be assessed.