Effect of cimetidine on the absorption of vitamin B12

Scand J Gastroenterol. 1982 Jan;17(1):129-31. doi: 10.3109/00365528209181056.


The effect of cimetidine on the absorption of orally administered crystalline or food (egg yolk-bound) vitamin B12 (B12) was studied in 13 patients. Absorption or crystalline B12 was normal and not significantly changed by cimetidine. In contrast, the uptake of food-bound B12 decreased in all patients, from a mean of 5.3% without the drug to 2.5% after it, a fall of 53% (p less than 0.0001). This impairment of B12 absorption raises the possibility that long-term, full-dose therapy with cimetidine may produce B12 deficiency similar to that seen in other hypochlorhydric states. Our data indicate that cimetidine-induced B12 malabsorption would not be detected by the standard Schilling test.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Absorption
  • Adult
  • Cimetidine / adverse effects
  • Cimetidine / pharmacology*
  • Egg Yolk
  • Female
  • Guanidines / pharmacology*
  • Humans
  • Male
  • Vitamin B 12 / metabolism*
  • Vitamin B 12 Deficiency / chemically induced


  • Guanidines
  • Cimetidine
  • Vitamin B 12