Colchicine and Ritonavir: 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
Ritonavir
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.
Ritonavir can make colchicine build up in your body, and that can be dangerous. Your body normally breaks down and clears colchicine using an enzyme (CYP3A4) and a transporter (P-gp). Ritonavir blocks both of these, so colchicine levels can climb much higher than intended. Too much colchicine can cause severe, even life-threatening problems, so taking the usual dose of both together is not recommended.
The good news is that this is well known and your care team can manage it. Please don't stop either medicine on your own. Talk with your pharmacist or doctor, because your colchicine dose may need to be lowered or your regimen adjusted to keep you safe.
Interaction: Ritonavir is a dual strong CYP3A4 and P-gp inhibitor; colchicine is a substrate of both. Co-administration reduces colchicine clearance, increasing exposure and risk of life-threatening/fatal toxicity. Direction: increased colchicine effect. Evidence: established.
- Contraindicated in patients with renal or hepatic impairment, and at therapeutic colchicine doses.
- In normal renal/hepatic function, dose reduction is required (including if ritonavir taken within prior 14 days).
- Gout flare: 0.6 mg once, then 0.3 mg 1 hour later; do not repeat sooner than every 3 days.
- Prophylaxis: reduce accordingly (e.g., 0.6 mg BID to 0.3 mg daily; 0.6 mg daily to 0.3 mg every other day).
- FMF: max 0.6 mg/day.
Monitor for GI, neuromuscular, and hematologic toxicity.
What happens
Increased colchicine exposure and an increased risk of colchicine toxicity
Interaction Deep Dive
Both CYP3A4 and P-gp metabolize colchicine, which serves as a substrate for each. Because fatal and life-threatening colchicine toxicity has been documented in patients taking therapeutic doses, giving colchicine together with agents that strongly inhibit both CYP3A4 and P-gp, such as ritonavir, is contraindicated1. In addition, combining colchicine with ritonavir is contraindicated when a patient has renal or hepatic impairment3. Patients whose renal and hepatic function is normal, but who are currently taking ritonavir or have taken it within the previous 14 days, must have their colchicine dose modified. When managing a gout flare while ritonavir is being taken, the modified oral colchicine regimen consists of a single 0.6 mg dose, then 0.3 mg one hour afterward, with repetition permitted no sooner than once every 3 days. For gout prophylaxis, an originally planned oral dose of 0.6 mg twice daily should be reduced to 0.3 mg once daily, while an originally planned oral dose of 0.6 mg once daily should be reduced to 0.3 mg every other day. For patients with familial Mediterranean fever taking ritonavir, colchicine should not exceed a maximum oral dose of 0.6 mg per day (which may be administered as 0.3 mg twice daily)42.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of colchicine; inhibition of P-gp-mediated efflux transport of colchicine
How to manage this interaction
This combination needs your care team's oversight. Standard colchicine doses with ritonavir are not recommended, and the combination is avoided entirely if you have kidney or liver problems.
- Keep taking both only as prescribed and do not adjust doses yourself.
- Your team may lower your colchicine dose and space it out. For example, dosing for a gout flare or daily prevention is typically reduced when ritonavir is on board (including if you took ritonavir in the last 14 days).
- Watch for and report muscle weakness, numbness, severe diarrhea, vomiting, or unusual bruising.
Ask your pharmacist or prescriber to confirm the right colchicine dose for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) In a study involving 18 patients, taking a 0.6 mg dose of colchicine together with ritonavir 100 mg twice daily over 5 days produced increases from baseline of 184.4% in colchicine Cmax and 296% in colchicine AUC 2.
b) In a study involving 23 patients, taking a 0.6 mg dose of colchicine together with clarithromycin 250 mg twice daily over 7 days produced increases from baseline of 227.2% in colchicine Cmax and 281.5% in colchicine AUC 2.
Common questions
Can I take Colchicine and Ritonavir together?
Ritonavir sharply raises colchicine levels and can cause fatal toxicity, so full-dose colchicine with ritonavir is contraindicated. Do not combine them at normal doses without your care team lowering and individualizing the colchicine dose. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Colchicine and Ritonavir 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 Ritonavir interaction managed?
This combination needs your care team's oversight. Standard colchicine doses with ritonavir are not recommended, and the combination is avoided entirely if you have kidney or liver problems. Keep taking both only as prescribed and do not adjust doses yourself. Your team may lower your colchicine dose and space it out. For example, dosing for a gout flare or daily prevention is typically reduced wh… Management is individual — always follow your own care team's guidance.
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 Colchicine or Ritonavir 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 (4)
- 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
- Product Information: NORVIR(R) oral tablets, oral solution, ritonavir oral tablets, oral solution. AbbVie Inc. (per manufacturer), North Chicago, IL, 2016. DailyMed
Keep reading about Ritonavir
Keep reading about Colchicine
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