Ribociclib and Clindamycin: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ribociclib
Clindamycin
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.
You've been prescribed ribociclib (Kisqali) along with the antibiotic clindamycin. Ribociclib slows down a liver enzyme (called CYP3A4) that your body uses to break down clindamycin. When that enzyme is slowed, more clindamycin can build up in your body, which may make side effects like stomach upset or diarrhea more likely.
The good news is that this is mostly a theoretical concern based on how these drugs work, not something proven to cause big problems together. Please keep taking both exactly as prescribed, and let your pharmacist or doctor know if you notice new or worsening side effects. Your care team can watch for this and adjust things if needed.
Mechanism: Ribociclib is a strong CYP3A4 inhibitor. Clindamycin is partially metabolized by CYP3A4, so inhibition may reduce its clearance and increase systemic exposure (AUC/Cmax), raising the risk of concentration-related adverse effects (GI intolerance, diarrhea). Neither drug is a prodrug here, so the direction is increased clindamycin effect.
- Direction: increased CYP3A4-substrate exposure
- Magnitude: not quantified for clindamycin; midazolam Cmax/AUC rose significantly in a healthy-subject study
- Onset: unspecified
- Evidence: theoretical/extrapolated
Management: Monitor for enhanced clindamycin adverse reactions; the substrate dose may need to be reduced and individualized by the care team.
What happens
Increased exposure of CYP3A4 substrate and an increased risk of CYP3A4 substrate-related adverse reactions
Interaction Deep Dive
When ribociclib, which strongly inhibits CYP3A4, is taken together with CYP3A4 substrates that have a narrow therapeutic index, the substrate's exposure can rise, and adverse reactions related to that substrate can likewise increase. A drug interaction study conducted in healthy subjects showed that giving ribociclib alongside midazolam (a sensitive CYP3A4 substrate) produced marked elevations in the Cmax and AUC of midazolam. During concurrent administration, watch for heightened adverse reactions associated with the CYP3A4 substrate. It may be necessary to lower the dose of the CYP3A4 substrate1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by ribociclib
How to manage this interaction
Here is how a care team typically handles this combination:
- Keep taking both as prescribed unless your doctor tells you otherwise.
- Your team may monitor you more closely for clindamycin side effects such as diarrhea, stomach cramps, or nausea.
- The dose of clindamycin may be adjusted and individualized by your prescriber if needed.
Let your pharmacist or doctor know promptly if you develop new or worsening digestive symptoms, especially persistent or severe diarrhea. This interaction is manageable with attention and follow-up.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study conducted in healthy subjects, giving ribociclib 400 mg once daily for 8 days together with midazolam raised midazolam Cmax by 2.1-fold and AUC(inf) by 3.8-fold. When ribociclib is given at 600 mg once daily, midazolam Cmax is projected to rise by 2.4-fold and AUC by 5.2-fold 1.
Common questions
Can I take Ribociclib and Clindamycin together?
Ribociclib can slow the breakdown of clindamycin and raise its levels, so watch for more side effects like diarrhea and stomach upset. Keep taking both as prescribed and report any new symptoms to your care team, who can monitor you and adjust the dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Ribociclib and Clindamycin 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 Ribociclib and Clindamycin interaction managed?
Here is how a care team typically handles this combination: Keep taking both as prescribed unless your doctor tells you otherwise. Your team may monitor you more closely for clindamycin side effects such as diarrhea, stomach cramps, or nausea. The dose of clindamycin may be adjusted and individualized by your prescriber if needed. Let your pharmacist or doctor know promptly if you develop new or w… 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 Ribociclib or Clindamycin 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: KISQALI(R) oral tablets, ribociclib oral tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2025. DailyMed
Keep reading about Ribociclib
Keep reading about Clindamycin
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.
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