Bacteriostatic Water (BAC Water) is a sterile, non-pyrogenic solution of water containing 0.9% benzyl alcohol, which acts as a preservative to inhibit bacterial growth
We primarily recommend Vitamin B12 injections for patients with conditions that impede B12 absorption, such as pernicious anemia, gastrectomy, Crohns disease, or Vitamin B12 malabsorption
Clinical Microbiology Reviews, 2020
Chloramphenicol should be discontinued if anemia attributable to chloramphenicol is noted during periodic blood studies, which should be done approximately every 2 days during chloramphenicol receipt
If you are not deficient and are taking it as a supportive measure, you might not feel any dramatic change, and thats okay