Chloroquine and Praziquantel: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Praziquantel
Chloroquine
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 praziquantel bioavailability
Interaction Deep Dive
Chloroquine has been shown to decrease the bioavailability and the maximum serum concentration of praziquantel in humans. A large amount of interindividual variation did occur in this study, possibly because praziquantel undergoes extensive first-pass metabolism. Dose increases of praziquantel may be necessary in patients receiving chloroquine1.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) Because of the possibility of dual infections with malaria and schistosomiasis, the effect of chloroquine on the pharmacokinetics of praziquantel were studied in eight healthy male volunteers. Each participant received an oral dose of praziquantel 40 mg/kg alone and in combination with chloroquine 600 mg. Mean maximum concentrations (Cmax) of praziquantel alone were 2.13 mcg/mL and decreased to 0.88 mcg/mL in the presence of chloroquine. Area under the concentration-time curve (AUC) of praziquantel also significantly decreased from 11.75 mcg/h/mL to 4.17 mcg/h/mL when given with chloroquine. However, one of the eight volunteers did not have any significant pharmacokinetic alterations, suggesting that a large interindividual variation exists. This has been explained by the wide variation in the metabolism of praziquantel, which undergoes extensive first-pass metabolism. Chloroquine may decrease the curative rate of praziquantel, especially in individuals who appear to metabolize praziquantel more quickly than others. Clinicians should be aware that patients also receiving chloroquine may need increased praziquantel doses 1.
Common questions
Can I take Chloroquine and Praziquantel together?
Decreased praziquantel bioavailability Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chloroquine and Praziquantel 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 Chloroquine or Praziquantel 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 (1)
- Masimirembwa CM, Naik YS, & Hasler JA: The effect of chloroquine on the pharmacokinetics and metabolism of praziquantel in rats and in humans. Biopharm Drug Dispos 1994; 15:33-43. PubMed
Keep reading about Praziquantel
Keep reading about Chloroquine
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