Colchicine and Simeprevir: 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
Simeprevir
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.
Taking these two together needs a close look with your care team. Simeprevir can slow down a natural "pump" (called P-gp) that normally helps your body get rid of colchicine. When that pump is blocked, colchicine can build up to higher levels than expected.
Colchicine at high levels can cause serious problems like severe stomach upset, muscle weakness, and effects on your blood cells. This is why the two are usually not used together. The good news is that your pharmacist and doctor can manage this by lowering your colchicine dose, spacing it out, or choosing a different plan. Please talk with them before making any changes on your own.
Direction: Simeprevir inhibits P-gp mediated colchicine efflux, increasing colchicine exposure and toxicity risk. Colchicine is a P-gp (and CYP3A4) substrate; neither drug's activation depends on this pathway.
- Effect: Increased colchicine AUC/Cmax; risk of life-threatening or fatal toxicity (GI, myelosuppression, neuromuscular).
- Severity: Contraindicated. Evidence is theoretical, extrapolated from documented toxicity with other P-gp/CYP3A4 inhibitors.
- Contraindicated in renal or hepatic impairment.
- Management: If coadministration is required in patients with normal renal/hepatic function, reduce colchicine daily dose or dosing frequency and monitor closely for toxicity.
What happens
Increased colchicine exposure and an increased risk of colchicine toxicity
Interaction Deep Dive
As a substrate of both CYP3A4 and P-gp, colchicine has been associated with toxicity when given together with clarithromycin, which inhibits both CYP3A4 and P-gp. Similar toxic effects have been documented when colchicine was combined with a CYP3A4 inhibitor and when it was combined with a P-gp inhibitor3. Using colchicine at the same time as P-gp inhibitors is contraindicated, since life-threatening and fatal colchicine toxicity has occurred in such patients even when colchicine was taken at therapeutic doses 1. This combination is likewise contraindicated in individuals with renal or hepatic impairment, because life-threatening and fatal drug interactions have been reported. For patients whose renal and hepatic function is normal 2, when colchicine must be given together with a P-gp inhibitor, the colchicine dose should be modified, either by lowering the total daily dose or by decreasing how often it is given. 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 two together, since this combination is generally contraindicated.
- If you have any kidney or liver problems, the combination is not used.
- If both are truly needed and your kidney and liver function are normal, your colchicine dose may be reduced or given less often, individualized by your team.
- Watch you more closely for signs of colchicine toxicity.
What you should do: Keep taking both exactly as prescribed for now, and contact your pharmacist or prescriber before changing anything. Report severe diarrhea, vomiting, muscle pain or weakness, numbness, or unusual bruising right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Colchicine and Simeprevir together?
Simeprevir can raise colchicine to dangerous levels by blocking its P-gp clearance, so this combination is generally contraindicated. Do not combine them without your prescriber's guidance, and seek help for severe GI, muscle, or bleeding symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colchicine and Simeprevir 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 Simeprevir interaction managed?
What your care team may do: Often avoid using these two together, since this combination is generally contraindicated. If you have any kidney or liver problems, the combination is not used. If both are truly needed and your kidney and liver function are normal, your colchicine dose may be reduced or given less often, individualized by your team. Watch you more closely for signs of colchicine toxic… 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 Simeprevir 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 Simeprevir
Keep reading about Colchicine
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist