The duration of a B12 injections effects varies, but most people experience benefits for a few weeks to a few months
The right choice depends on deficiency cause, route preference, tolerability, availability, and monitoring needs
Its like wondering if you have a flat tire, but instead of leaving your car to check, you rely on the wobbly handling of your car on the road to indicate that you probably have a flat tire
NHS approach to B12 deficiency: NICE Clinical Knowledge Summaries recommend investigating B12 deficiency in patients presenting with macrocytic anaemia, unexplained neurological symptoms, or risk factors including pernicious anaemia, gastrectomy, malabsorption disorders, metformin use, proton pump inhibitors, or nitrous oxide exposure