<unk> , also known as vitamin B12a and<unk> , is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat vitamin B12 deficiency including pernicious anemia. Other uses include treatment for cyanide poisoning, Leber's optic atrophy, and toxic amblyopia. It is given by injection into a muscle or vein. Side effects are generally few. They may include diarrhea, low blood potassium, allergic reactions, and high blood pressure. Normal doses are considered safe in pregnancy.<unk>  is the natural form of vitamin B12 and a member of the cobalamin family of compounds.<unk> , or another form of vitamin B12, are required for the body to make DNA.<unk>  was first isolated in 1949. It is on the World Health Organization's List of Essential Medicines.<unk>  is available as a generic medication. Commercially it is made using one of a number of types of bacteria.
Hydroxocobalamin
Cyanocobalamin
Sodium thiosulfate 
Dimethyl methylphosphonate
Acetylcysteine
Fomepizole
Penicillamine
Zinc pyrithione