The present invention relates generally to vitamin B12 nasal spray compositions and methods of using the same in the treatment of vitamin B12 deficiency and various disorders that are related to such deficiency. In particular embodiments, the present invention is directed to treatment methods comprising intranasal administration of a cobalamin composition according to a particular dosing and frequency schedule and to a preservative-free nasal spray composition comprising a cobalamin compound useful in the practice of such treatment methods.