Is Vitamin B12 (Cobalamin) Safe with Fluoxetine?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Monitor B12 levels annually with long-term use. Consider supplementing with 500–1000 mcg of methylcobalamin daily if levels are low or borderline.
Why this interaction occurs
Chronic SSRI use may interfere with B12 absorption and utilization through effects on gastric function and the methylation pathway. B12 deficiency can worsen depression, cause neurological symptoms, and mimic or exacerbate SSRI side effects such as fatigue and cognitive fog.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 87,365 reports mentioning Fluoxetine. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Fluoxetine + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Vitamin B12 (Cobalamin) interactions → · All Fluoxetine interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.