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Vitamin B12
How it is taken
The schedule
| Route | Injection under the skin or into the muscle |
|---|---|
| Amount to start | 1000 mcg |
| How often | Once a week for the loading run, then once a month |
| When | Same day each week, any time of day |
| Steps up and down |
|
| How long | Four to eight weeks loading, then ongoing monthly |
| Cycle | No cycle and no break; this is replacement, not a course |
| Mixing | None. It is supplied as a ready-made pink to red liquid, most often 1000 mcg per mL, so one dose is 1 mL, which reads as 100 units on a U-100 syringe. |
| Storage | Fridge, upright, kept in its box and out of the light, because cobalamins break down in light. A vial that loses colour or turns cloudy is finished. |
It is injected under the skin or into muscle, which skips the stomach and ileum entirely. A common refill is 1000 mcg once a week for the first four to eight weeks, then 1000 mcg once a month to hold the level. Methylcobalamin is the form chosen when nerve repair is the goal, and cyanocobalamin or hydroxocobalamin do the same job for a plain shortage. There is no need for a break, since this is replacement of something you cannot make.
Your personal schedule is set after we review your survey.
Sources
Read the original sources
- NIH: Vitamin B12 fact sheet (NIH Office of Dietary Supplements · Official nutrient fact sheet · checked 2026-10-08)
- Clinical practice: vitamin B12 deficiency (Summary · checked 2026-10-13)