Ask three people how often you should get B12 shots for maximum benefit, and you will get three answers. The real answer depends on why you are deficient. This guide explains the NHS loading and maintenance schedules, why hydroxocobalamin lasts longer than cyanocobalamin, when high-dose oral B12 works as well as injections, and why injections do nothing for people with normal levels. Written for anyone in Knutsford and Cheshire weighing up a B12 programme.