Didanosine and Ketoconazole: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ketoconazole
Didanosine
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.
What happens
Decreased ketoconazole effectiveness
Interaction Deep Dive
Didanosine pediatric powder for oral solution and chewable/buffered tablets contain antacids that can raise the stomach pH. If ketoconazole and didanosine pediatric powder for oral solution or chewable/buffered tablets are used concomitantly, ketoconazole should be administered at least two hours before didanosine. No specific administration adjustments are recommended for the concomitant use of didanosine delayed release capsules/enteric coated beadlets and ketoconazole12.
Why it happens (mechanism)
Decreased ketoconazole absorption due to increased gastrointestinal pH
Literature reports
1 report — tap to read
a) Ketoconazole, 200 mg/day for 4 days administered 2 hours before didanosine powder for solution, 375 mg every 12 hours for 4 days in 12 HIV-infected patients resulted in a decrease in ketoconazole AUC and Cmax by 14% and 20%, respectively. There was no significant change in the AUC and a 12% decrease in the Cmax of didanosine 2.
Common questions
Can I take Didanosine and Ketoconazole together?
Decreased ketoconazole effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Didanosine and Ketoconazole interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Didanosine or Ketoconazole 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 anything you'd monitor while I'm on both?
References (2)
- Product Information: VIDEX EC(R) delayed release oral capsules, enteric coated beadlets, didanosine delayed release oral capsules, enteric coated beadlets. Bristol-Myers Squibb Company, Princeton, NJ, 2009.
- Product Information: VIDEX(R) pediatric powder for oral solution, didanosine pediatric powder for oral solution. Bristol-Myers Squibb Company, Princeton, NJ, 2009.
Keep reading about Ketoconazole
Keep reading about Didanosine
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