Griseofulvin (trade names: Gris-peg and Grifulvin V) is an orally administered antifungal drug. It is used both in animals and humans, to treat fungal infections of the skin (commonly known as ringworm) and nail fungus. It was discovered in the culture broth of certain species of the mold Penicillium in 1939. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. It is produced industrially by fermenting the fungus Penicillium patulum.