Vitamin B12 is mainly in animal products like meat, fish, and dairy
If you are concerned about getting every last unit out of a vial, they are worth the small extra investment
For the mechanics of measuring accurately, our reconstitution guide and the dosage calculator do the math
Anyway, the fact is that some people manage perfectly well on a 1mg injection every three months but others, and the vast majority of the PA Society do not, and they feel a return of their symptoms, or their family and friends notice a return of their symptoms long before their next injection is due
If your parent takes any of these, ask their prescriber to check B12, MMA, and homocysteine levels at their next visit