Cyanocobalamin Injection and Colchicine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Cyanocobalamin Injection
Colchicine
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased cyanocobalamin absorption
Interaction Deep Dive
Colchicine therapy is associated with reduced cyanocobalamin absorption2, with the greatest reductions observed with tubal administration directly into the ileum. The effects were reversible with colchicine discontinuation 3.
Why it happens (mechanism)
Disruption of intestinal mucosal function
Literature reports
2 reports — tap to read
a) In a subgroup analysis of 11 obese patients given colchicine while maintaining a nutritionally-stable diet, consistent reductions in vitamin B12 absorption were noted in 3 patients administered colchicine (2.6 to 3.9 mg/day) plus 0.25 microcuries/day of cobalt 57-labeled vitamin B12. Schilling tests showed decreased vitamin B12 absorption during colchicine periods, with a decrease to subnormal levels (less than 7%) in 2 of the 3 patients. Vitamin B12 excretion increased between the control and recovery periods for patient 1 (22.5% to 27%), patient 2 (22.2% to 29.5%), and patient 3 (24% to 40%). Levels returned to normal following colchicine withdrawal 2.
b) Oral colchicine reduced cyanocobalamin absorption in 18 out of 19 patients studied, with the greatest reductions reported with direct delivery to the ileum. Three male and 16 female patients (18 obese and 1 with hyperlipemia) were given a constant diet and administered daily oral doses of 0.1 microcuries of cobalt 57-labeled vitamin B12 followed by 1 mg of intramuscular vitamin B12 two hours later. Urine and feces were analyzed for cobalt 57 during control periods, with administration of colchicine (1.9 to 3.6 mg/day by mouth or tube over 4 to 8 days), and with cascara sagrada fluid extract (18 mL) given during control periods. Overall, there were significant decreases in vitamin B12 absorption during colchicine periods (p less than 0.01), with all but one patient having higher vitamin B12 excretion after colchicine than before. The greatest reductions in absorption (less than 5% excretion) were noted when colchicine was administered by tube directly into the ileum. Three to five days after colchicine withdrawal, vitamin B12 levels returned to baseline in all but one patient 3.
Common questions
Can I take Cyanocobalamin Injection and Colchicine together?
Decreased cyanocobalamin absorption Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cyanocobalamin Injection and Colchicine interaction?
It is rated minor. Usually limited clinical impact.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Cyanocobalamin Injection or Colchicine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (3)
- Palopoli JJ & Waxman J: Colchicine neuropathy or vitamin B12 deficiency neuropathy?. N Engl J Med 1987; 317(20):1290-1291.
- Race TF, Paes IC, & Faloon WW: Intestinal malabsorption induced by oral colchicine. Comparison with neomycin and cathartic agents. Am J Med Sci 1970; 259(1):32-41. PubMed
- Webb DI, Chodos RB, Mahar CQ, et al: Mechanism of vitamin B12 malabsorption in patients receiving colchicine. N Engl J Med 1968; 279(16):845-850.
Keep reading about Colchicine
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