Clindamycin and Itraconazole: 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
Itraconazole
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 itraconazole (an antifungal) along with clindamycin (an antibiotic). Itraconazole slows down a liver enzyme called CYP3A4 that helps your body break down clindamycin. Because of this, more clindamycin may build up in your blood than usual. That could mean a higher chance of side effects like stomach upset, nausea, diarrhea, or other reactions.
Here's the reassuring part: this concern is mostly theoretical, and your care team can manage it easily. They may keep a closer eye on how you feel and can adjust your dose if needed. Keep taking both as prescribed, and let your pharmacist or doctor know if you notice new or worsening symptoms.
Effect: Itraconazole, a potent CYP3A4 inhibitor, may reduce clindamycin metabolism (clindamycin is a partial CYP3A4 substrate), increasing clindamycin exposure (AUC/Cmax) and the risk of concentration-related adverse effects (GI intolerance, potential for C. difficile-associated diarrhea).
- Mechanism: inhibition of CYP3A4-mediated clindamycin metabolism.
- Direction: increased substrate exposure (neither is a relevant prodrug here).
- Onset: unspecified.
- Evidence: theoretical.
- Management: monitor for clindamycin-related adverse reactions; dose reduction may be considered and individualized by the care team.
What happens
Increased CYP3A4 substrate exposure and an increased risk of CYP3A4 substrate-related adverse effects
Interaction Deep Dive
When itraconazole (a strong inhibitor of CYP3A4) is given alongside substrates of CYP3A4, the plasma levels of those substrates can rise, which may lead to a greater incidence of adverse reactions associated with them. Watch for adverse reactions. It may be necessary to lower the dose of the co-administered drug12.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by itraconazole
How to manage this interaction
Good news: this interaction can be managed, and you should keep taking both medications exactly as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for clindamycin side effects such as nausea, stomach pain, or diarrhea.
- Your clindamycin dose may need to be adjusted and individualized by your care team if side effects appear.
- Report any new or worsening symptoms, especially persistent or severe diarrhea, to your pharmacist or doctor promptly.
If you have questions about combining these two, your pharmacist can review your full medication list with you.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Clindamycin and Itraconazole together?
Itraconazole can raise clindamycin levels by slowing its breakdown, so watch for more side effects like stomach upset or diarrhea; keep taking both as prescribed and tell your care team about any new symptoms so they can adjust or monitor as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Clindamycin and Itraconazole 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 Clindamycin and Itraconazole interaction managed?
Good news: this interaction can be managed, and you should keep taking both medications exactly as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for clindamycin side effects such as nausea, stomach pain, or diarrhea. Your clindamycin dose may need to be adjusted and individualized by your care team if side effects appear. Report any new or worse… 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 Clindamycin or Itraconazole 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 (2)
Keep reading about Itraconazole
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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