Colchicine and Vemurafenib: 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
Vemurafenib
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.
These two medicines can be a risky combination. Vemurafenib (Zelboraf) can block a 'pump' in your body called P-glycoprotein that normally helps push colchicine (Colcrys, Mitigare) out. When that pump is slowed, colchicine can build up to much higher levels than intended.
That matters because too much colchicine can cause serious problems, like severe stomach upset, diarrhea, muscle weakness, and in rare cases life-threatening toxicity. Because of this, taking them together is generally not recommended. The good news is your care team knows how to handle this, by adjusting your colchicine or choosing another option. Please talk with your doctor or pharmacist before combining them.
Effect: Vemurafenib may inhibit P-gp-mediated efflux of colchicine, increasing colchicine exposure and risk of toxicity. Colchicine is a P-gp (and CYP3A4) substrate; neither drug is a prodrug, so inhibition raises the active colchicine level.
- Direction: Increased colchicine exposure/AUC.
- Severity: Contraindicated per labeling for colchicine with P-gp inhibitors.
- Evidence: Theoretical, extrapolated from documented P-gp/CYP3A4 inhibitor cases (e.g., clarithromycin).
- Management: Avoid combination, especially with renal or hepatic impairment. If unavoidable in patients with normal organ function, reduce colchicine daily dose or dosing frequency and monitor closely for toxicity (GI, myelosuppression, neuromuscular).
What happens
Increased colchicine exposure and an increased risk of colchicine toxicity
Interaction Deep Dive
Colchicine acts as a substrate for both CYP3A4 and P-gp. Instances of toxicity have been documented when it is given together with clarithromycin, an agent that inhibits both CYP3A4 and P-gp. Similarly, toxicity has been seen when colchicine is combined with a CYP3A4 inhibitor and when it is combined with a P-gp inhibitor3. Because life-threatening and fatal colchicine toxicity has been reported in patients taking colchicine at therapeutic doses, the concurrent use of colchicine with P-gp inhibitors is contraindicated 1. This combination is likewise contraindicated in individuals with renal or hepatic impairment, since life-threatening and fatal drug interactions have been observed. For patients whose renal and hepatic function is normal 2, when colchicine must be given alongside a P-gp inhibitor, modify the colchicine dose by lowering either the daily amount or the frequency of dosing. Watch carefully for signs of colchicine toxicity 3.
Why it happens (mechanism)
Inhibition of P-gp-mediated colchicine efflux transport
How to manage this interaction
What your care team may do:
- Often avoid using these together, since colchicine with a P-gp inhibitor is contraindicated, particularly if you have kidney or liver problems.
- If both are truly needed and your kidney and liver function are normal, your colchicine dose may need to be adjusted and individualized, either a lower daily dose or less frequent dosing.
- Monitor you more closely for signs of colchicine toxicity.
What you should do: Keep taking both exactly as prescribed and do not change anything on your own. Contact your prescriber or pharmacist promptly if you notice severe diarrhea, vomiting, muscle weakness or pain, numbness, or unusual fatigue.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Colchicine and Vemurafenib together?
Vemurafenib can raise colchicine levels and this combination is generally contraindicated, so check with your doctor or pharmacist before using them together and watch for signs of colchicine toxicity. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colchicine and Vemurafenib interaction?
It is rated contraindicated. These should generally not be used together.
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 Vemurafenib interaction managed?
What your care team may do: Often avoid using these together, since colchicine with a P-gp inhibitor is contraindicated, particularly if you have kidney or liver problems. If both are truly needed and your kidney and liver function are normal, your colchicine dose may need to be adjusted and individualized, either a lower daily dose or less frequent dosing. Monitor you more closely for signs of co… 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.
Questions for your pharmacist
- Does my dose of Colchicine or Vemurafenib 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 (3)
- Product Information: LODOCO(R) oral tablets, colchicine oral tablets. AGEPHA Pharma USA, LLC (per FDA), Parsippany, NJ, 2023. DailyMed
- Product Information: COLCRYS oral tablets, colchicine oral tablets. Takeda Pharmaceuticals America Inc (per FDA), Deerfield, IL, 2020. DailyMed
- Product Information: GLOPERBA(R) oral solution, colchicine oral solution. Romeg Therapeutics LLC (per FDA), Woburn, MA, 2019. DailyMed
Keep reading about Vemurafenib
Keep reading about Colchicine
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