Didanosine and Hydroxyurea: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Hydroxyurea
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
An increased risk of peripheral neuropathy, fatal pancreatitis and hepatotoxicity
Interaction Deep Dive
Lactic acidosis and severe hepatomegaly with steatosis, sometimes fatal, have been reported with the use of nucleoside analogues, such as stavudine, alone or in combination with didanosine with or without hydroxyurea. A majority of these cases were women5. Due to the increased risk of severe peripheral neuropathy, pancreatitis and fatal hepatotoxicity, the combination of didanosine plus hydroxyurea, with or without stavudine, should be avoided 321. If unavoidable, monitor patients closely for signs and symptoms of pancreatitis and permanently discontinue therapy with hydroxyurea in patients who develop signs and symptoms of pancreatitis 21.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) The addition of hydroxyurea to a medication regimen consisting of didanosine, stavudine, and nevirapine resulted in pancreatitis in a case report. A 26-year-old HIV positive man receiving stavudine 40 mg twice daily, nevirapine 200 mg twice daily, and didanosine 400 mg daily was prescribed hydroxyurea 500 mg twice daily to intensify treatment. The viral load decreased from 81,747 copies/mL to 237 copies/mL, however, the patient began to experience malaise and pain in the upper abdomen. Hydroxyurea was discontinued after 42 days. Three weeks later he was admitted to the hospital with severe pain, vomiting, fever, tenderness of the upper abdomen, and guarding three weeks later. Amylase was 746 units (normal range: less than 300) with neutrophil leukocytosis. Computed tomography demonstrated changes consistent with pancreatitis. All medications were discontinued. The author concludes that the addition of hydroxyurea to this patient's treatment regimen may have precipitated didanosine induced pancreatitis 4.
b) Pancreatitis, peripheral neuropathy, and liver function abnormalities occur more frequently in patients treated with the combination of stavudine and didanosine, with or without hydroxyurea. Pancreatitis resulting in death was observed in patients treated with stavudine plus didanosine, with or without hydroxyurea, in controlled clinical studies and in postmarketing reports. Patients treated with this combination should be closely monitored for signs of liver toxicity 5.
Common questions
Can I take Didanosine and Hydroxyurea together?
An increased risk of peripheral neuropathy, fatal pancreatitis and hepatotoxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Didanosine and Hydroxyurea interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Didanosine or Hydroxyurea 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 (5)
- Product Information: SIKLOS(R) oral tablets, hydroxyurea oral tablets. Medunik USA (per FDA), Rosemont, PA, 2023. DailyMed
- Product Information: DROXIA(R) oral capsules, hydroxyurea oral capsules. H2-Pharma LLC (per FDA), Montgomery, AL, 2023. DailyMed
- Product Information: VIDEX EC oral delayed-release capsules, enteric-coated beadlets, didanosine oral delayed-release capsules, enteric-coated beadlets. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2018.
- Longhurst H & Pinching A: Pancreatitis associated with hydroxyurea in combination with didanosine. BMJ 2001; 322:81.
- Product Information: ZERIT(R) oral capsules, solution, stavudine oral capsules, solution. Bristol-Myers Squibb, Princeton, NJ, 2008. DailyMed
Keep reading about Hydroxyurea
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