A nosode is a homeopathically prepared remedy, made from a disease or pathological product. Nosodes are used in the same way as vaccines; they sensitize the body, prompting the immune system to react. Nosodes are oral in application and more dilute than vaccines.

The origin of the word nosode is the Greek word nosos, meaning disease. There is also a connection with the Latin word noxa, the root of the term noxious, in that the use of nosodes involves potentially dangerous, noxious materials as a basis for a remedy.#

There have been a number of cases of people falling ill aftyer relying on nosodes rather tahn real vaccination.