Going up and down

Dosing is driven by how empty you were and how much nerve is involved. A plain shortage with no nerve symptoms is well served by weekly then monthly 1000 mcg. Where nerves are involved, the loading run is held at weekly for the full eight weeks before dropping to monthly, and some practice keeps it at weekly for longer. B12 has no ceiling that forces you down: it is water-soluble, the kidneys clear what is not needed, and Japanese work in motor neurone disease ran as high as 25 and 50 mg into muscle. Going up is about how fast you refill, not about pushing past a limit.