Cimetidine and Vitamin B12: what the published research says
PubMed indexes 5 records that name Cimetidine and Vitamin B12 together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.
Every statement below is attributed to a named, dated, linked source.
This page lists published research relevant to Cimetidine and Vitamin B12. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.
A study appearing here is not proof that an interaction exists. Two substances can be named together in a paper that never tested them in combination, and a source listed as background may cover only one of them.
Findings are quoted from each abstract as the authors wrote them. NutriStack has not re-analysed, pooled, or reconciled them, and they may disagree with each other.
NutriStack’s own interaction assessment for this pair is not published here. It has not completed qualified-human clinical review, so it is withheld from search. See the publication gate.
Nothing here is medical advice. Decisions about prescription medication and supplements belong with your prescriber or pharmacist, who can see your full regimen.
The research
5 studies naming Cimetidine and Vitamin B12.
Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.
“However, group IV rats showed markedly immunopositive detached cells, spermatids, and primary spermatocytes. Cimetidine interferes with the control of spermatogenesis as evidenced by microscopic and ultrastructural studies and affection of ERĪ² receptors and vitamin B12 has a protective action against this harmful effect.”
Names both Cimetidine and Vitamin B12 in its title.
“Although cimetidine was not able to induce vitamin B(12) deficiency, this drug causes tubular atrophy due to Sertoli cell damage and loss of germ cells. However, vitamin B(12) supplement is able to stimulate spermatogenesis and restore the number of Sertoli cells, softening the harmful effect of cimetidine on spermatogenesis.”
Names both Cimetidine and Vitamin B12 in its title.
Scandinavian journal of gastroenterology · 1982 · PMID 7134827
Research Support, U.S. Gov't, Non-P.H.S.Human subjects13 participants
“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.”
Names both Cimetidine and Vitamin B12 in its title.
“Two men developed gynaecomastia, one died of myocardial infarction and one had transient sinus bradycardia during cimetidine medication. Cimetidine improves the symptomatic state and postpones ulcer recurrence as long as treatment is maintained.”
Names Cimetidine and Vitamin B12 together in an interaction, co-administration, or pharmacokinetic context.
The American journal of gastroenterology · 1980 · PMID 6782861
Case ReportsResearch Support, U.S. Gov't, Non-P.H.S.Human subjects
“These results indicate that effective long-term control of histamine-induced gastric hypersecretion can be achieved with cimetidine. They suggest that some of the cutaneous symptoms of mastocytosis are mediated via histamine H2 receptors in the skin.”
Names Cimetidine and Vitamin B12 together in an interaction, co-administration, or pharmacokinetic context.
Limitations
What this evidence cannot tell you.
Search-based evidence indexes have real limits, and it is worth being explicit about them:
Selection. These records were found by searching PubMed titles and abstracts for both substance names alongside interaction and pharmacokinetic terms. Relevant work that phrases things differently, or is not indexed in PubMed, will be missing.
No effect size. The quoted conclusions are the authors’ words about their own study. We have not extracted effect direction or magnitude, and a single study’s conclusion is not a consensus.
Population mismatch. Findings in healthy volunteers, animals, or a specific patient group may not transfer to you, your dose, or your formulation.
Absence is not safety. Few published studies means the combination is under-studied, which is not the same as established as safe.
Nearby evidence
Other pairs with published research.
Pages covering Cimetidine or Vitamin B12 alongside a different substance.
NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers Cimetidine, Vitamin B12, and several hundred other substances.
The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.
NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.
