who shouldnt have b12 injections Are Shots Safe? Royal Palm Beach Medical Group Vitamin B12 Deficiency in Adults:

We've reviewed protocols where researchers drew 'about a quarter of the syringe' for each dose because they never calculated the exact unit marking

Temporary blindness may last as long as 2-3 weeks

More commonly though, deficiency is due to poor absorption of this large vitamin

Apr 17 2021;13(4)doi:10.3390/nu13041344 Alehagen U, Alexander J, Aaseth J, Larsson A, Lindahl TL

How to find the best vitamin B12 supplement Because vitamin B12 is water soluble (meaning it dissolves in water and is excreted in your urine), vitamin B12 supplements are very safe even at doses several times the recommended dietary allowances, Somer says

Among 113 Guatemalan women, plasma vitamin B-12 was deficient or low in nearly 50%, breast milk vitamin B-12 concentration was low in 31%, and low breast milk vitamin B-12 correlated significantly with infant urinary MMA (21)