Over the years, researchers have tested it to treat diseases such as scarlet fever, diphtheria, cancer of the uterus, and pneumonia. In the 1940s, it was tested on animals to see if it could treat carbon monoxide poisoning, hemorrhage, and toxic reactions of exposure to certain chemicals. It had no benefit against any of these conditions. Supporters of hydrogen peroxide believe that cancer cells grow best if they are deprived of oxygen. They claim that hydrogen peroxide, which is an oxygen solution, can cure cancer by bombarding cancer cells with more oxygen than they can handle.
Some proponents suggest that it can be used rectally, as a nasal spray, and as ear drops.
Hydrogen peroxide treatments go by many names, including hyperoxygenation, oxymedicine, oxidative therapy, bio-oxidative therapy, and oxydology. Treatment can be self-administered following instructions given in books and newsletters. Hydrogen peroxide therapy is also used in some Mexican cancer clinics. There is no evidence that hydrogen peroxide has value as a cancer treatment. According to the Centers for Disease Control and Prevention, people can be harmed by breathing its vapors, through skin contact, and from swallowing hydrogen peroxide.