Colchicine and Fluoxetine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fluoxetine
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.
Fluoxetine (an antidepressant) may raise the level of colchicine in your body. Colchicine is used for gout and some other conditions, and it can be harsh if too much builds up. Fluoxetine can slow down the liver pathway that clears colchicine, so more of it may stick around than intended.
Too much colchicine can cause things like stomach pain, nausea, diarrhea, muscle weakness, or unusual tiredness. The good news is this is very manageable. Your care team can adjust your colchicine dose and keep an eye on you. Please don't stop or change either medicine on your own, just check in with your pharmacist or doctor.
Mechanism: Fluoxetine inhibits CYP3A4 (and P-gp indirectly), reducing colchicine clearance and increasing colchicine exposure (AUC/Cmax). Colchicine is not a prodrug, so inhibition increases its effect and toxicity risk.
- Direction: Increased colchicine levels, increased toxicity risk.
- Severity: Major.
- Evidence: Theoretical.
- Onset: Unspecified.
Management: Avoid concomitant use when possible given potential for serious/life-threatening toxicity. If combined, reduce colchicine daily dose or dose frequency and monitor closely for colchicine toxicity (GI symptoms, myopathy, neuromyopathy, cytopenias). Consider greater caution in renal or hepatic impairment.
What happens
Increased colchicine exposure and an increased risk of colchicine-related toxicity
Interaction Deep Dive
Because of the risk of serious, potentially fatal toxicity, colchicine should not be taken together with CYP3A4 inhibitors. When concurrent administration cannot be avoided, the colchicine dose should be modified by lowering either the daily amount or how often it is given, along with close observation for signs of colchicine toxicity1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of colchicine
How to manage this interaction
Keep taking both as prescribed unless your care team tells you otherwise. Here is what they typically do with this combination:
- Where possible, they may avoid using the two together because high colchicine levels can be serious.
- If both are needed, your colchicine dose may need to be adjusted and individualized, either a lower daily dose or less frequent dosing.
- Your team may monitor you more closely for signs of colchicine toxicity.
Tell your pharmacist or doctor right away if you notice diarrhea, nausea, vomiting, stomach pain, muscle weakness, numbness, or unusual tiredness.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Colchicine and Fluoxetine together?
Fluoxetine can raise colchicine levels and increase the risk of serious colchicine toxicity, so this combination is best avoided; if both are needed your doctor can lower the colchicine dose and monitor you closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colchicine and Fluoxetine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Colchicine and Fluoxetine interaction managed?
Keep taking both as prescribed unless your care team tells you otherwise. Here is what they typically do with this combination: Where possible, they may avoid using the two together because high colchicine levels can be serious. If both are needed, your colchicine dose may need to be adjusted and individualized, either a lower daily dose or less frequent dosing. Your team may monitor you more clos… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Colchicine or Fluoxetine 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: MITIGARE(R) oral capsules, colchicine oral capsules. Hikma Specialty USA Inc (per FDA), Columbus, OH, 2024. DailyMed
Keep reading about Fluoxetine
Keep reading about Colchicine
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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