vitamin b12 injection reaction Compounded Cyanocobalamin (Vitamin B12) Possible allergic reaction to B12

William Castle demonstrated that gastric juice contained an "intrinsic factor" which when combined with meat ingestion resulted in absorption of the vitamin in this condition

[4] It is also possible to supplement with vitamin B12

Watch out for these early warning signs: Unusual fatigue and weakness Pale or yellowish skin Numbness or tingling in hands and feet Memory problems and confusion Sore, red tongue Balance problems Nerve damage can happen if B12 deficiency goes untreated

[DOI] [PMC free article] [PubMed] [Google Scholar] 152.Heine M, Fischer AW, Schlein C, Jung C, Straub LG, Gottschling K, et al

DrachJMcQueenTEngelHAndreeffMRobertsonKACollinsSJet al

However, definitive comparative dosage studies are still emerging in 2026