Tolerability (veterinary): Generally well tolerated in veterinary studies, with occasional mild injection-site reactions
Nausea or Upset Stomach: Some people may experience gastrointestinal discomfort, such as nausea, vomiting, or diarrhea, although these side effects are rare
Various inherited and lifestyle factors contribute to vitamin B12 deficiencies that impair such fundamental life processes as recycling of homocysteine, a potentially toxic metabolite, nerve cell signaling, mood and memory management, and healthy gene regulation (epigenetics), from pregnancy through old age
Alston, T
How often should you take B12
I bought two months worth and the first ampule had not the full four shots