Most single homeopathic medicines are available in several dilutions. The letter indicates which dilution process was chosen, while the number indicates how many times that dilution process was used, and consequently, which symptoms the medicine is meant to treat.
Here's a quick guide to using homeopathic medicines: Low dilutions, such as 6X or 6C, will relieve local symptoms — a symptom you can point a finger at (e.g., an insect bite or bruise). Medium dilutions, such as 12X, 9C or 12C, will relieve general symptoms — more than one symptom in more than one location (e.g., muscle aches and pains). High dilutions, such as 30X or 30C, will relieve general symptoms — more than one symptom in more than one location with possible behavioral or emotional symptoms (e.g., a very high fever and chills, accompanied by agitation or sleeplessness).
If a person has the right medicine, no matter what the dilution, they will see a lessening of symptoms. For most medicines, choosing the right dilution is merely fine-tuning. It may be helpful for you to use the Boiron Medicine Finder app to help select which medicines and dilutions are best to relieve your symptoms.